Beaver territories and
waterfowl breeding in beaver dams
in Klosterheden State Forest, Denmark
by Aurélie Charrin
directed by Sten Asbirk & Thomas Borup Svendsen
2004
BEAVER TERRITORIES IN KLOSTERHEDEN STATE FOREST AND
SURRONDINGS ...................................................................................................................... 4
A. INTRODUCTION ............................................................................................................... 4
1. PRESENTATION OF THE SPECIES : EUROPEAN BEAVER, CASTOR FIBER LINNAEUS 1758. ..... 4
1.1. Taxonomy .................................................................................................................... 4
1.2. Body description and characteristics.......................................................................... 4
1.3. Behaviour and ecology................................................................................................ 5
2. BEAVERS IN DENMARK ....................................................................................................... 8
B. BEAVER STUDY ................................................................................................................ 9
1. IN KLOSTERHEDEN FOREST DISTRICT .................................................................................. 9
1.1. Definition..................................................................................................................... 9
1.2. Møllesøen/Flynder Å ................................................................................................... 9
1.3. Ællebæk/Hestbæk ...................................................................................................... 11
1.4. Discussion on the methodology................................................................................. 12
2. BEAVER POPULATION ESTIMATIONS .................................................................................. 13
2.1. Introduction............................................................................................................... 13
2.2. Material and methods................................................................................................ 13
2.3. Results ....................................................................................................................... 14
2.4. Discussion ................................................................................................................. 15
3. OUTSIDE KLOSTERHEDEN STATE FOREST .......................................................................... 20
3.1. Investigation along Storå river ................................................................................. 20
3.2. Search for the lodge in Flobæk ................................................................................. 21
MONITORING OF WATER BIRDS IN THE BEAVER PONDS ................................... 22
A. INTRODUCTION ............................................................................................................. 22
B. MATERIAL AND METHODS ........................................................................................ 22
1. STUDY AREA ..................................................................................................................... 22
Description of the vegetation ........................................................................................... 22
2. OBSERVATIONS ................................................................................................................. 25
3. GRAPHICAL METHODOLOGY .............................................................................................. 25
C. RESULTS........................................................................................................................... 26
1. RESULTS BY SPECIES ......................................................................................................... 26
1.1. Mallard (Anas Platyrhychos) .................................................................................... 26
1.2. Muet swan (Cygnus olor) .......................................................................................... 26
1.3. Moorhen (Gallinula chloropus) ................................................................................ 27
1.4. Pied wagtail (Motacilla alba) ................................................................................... 27
1.5. Grey wagtail (Motacilla cinera) ............................................................................... 27
1.6. Little grebe (Tachybaptus ruficollis)......................................................................... 28
1.7. Grey heron (Ardea cinerea) ...................................................................................... 28
1.8. Cormorant(Phalacrocorax carbo) ............................................................................ 28
1.9. Kingfisher (Alcedo atthis) ......................................................................................... 28
1.10. Teal (Anas crecca) .................................................................................................. 28
1.11. Tufted duck (Aythya fuligula).................................................................................. 28
1.12. Coot (Fulica atra) ................................................................................................... 29
1.13. Sandpiper ................................................................................................................ 29
1.14. Egyptian goose (Alopochen aegyptiacus) ............................................................... 29
1.15. Water rail (Rallus aquaticus).................................................................................. 29
1.16. Black stork (Ciconia nigra)..................................................................................... 29
1.17. Shelduck (Tadorna tadorna) ................................................................................... 29
1.18. Black headed Gull (Larus ridibundus) and other gull (Larus sp.).......................... 29
1.19. Unindentificated duck ............................................................................................. 29
2. RESULTS BY TERRITORY .................................................................................................... 29
D. DISCUSSION..................................................................................................................... 30
1. RECORDS OF THE SPECIES .................................................................................................. 30
1.1. Mallard...................................................................................................................... 30
1.2. Muet swan ................................................................................................................. 31
1.3. Moorhen .................................................................................................................... 31
1.4. Little grebe ................................................................................................................ 31
1.5. Grey heron................................................................................................................. 32
1.6. Wagtail ...................................................................................................................... 32
1.7. Cormorant ................................................................................................................. 32
1.8. Sandpiper .................................................................................................................. 32
1.9. Unindenticated duck.................................................................................................. 33
2. RESULTS BY TERRITORY .................................................................................................... 33
3. BEAVERS’INFLUENCE. ....................................................................................................... 34
E. PASSERINES OBSERVATIONS.................................................................................... 35
1. RING-MARKING IN FRUERBÆK .......................................................................................... 35
2. OTHER OBSERVED SPECIES IN KLOSTERHEDEN ................................................................. 35
3. OTHER OBSERVATIONS ...................................................................................................... 37
ACKNOWLEDGEMENTS................................................................................................... 38
BIBLIOGRAPHY .................................................................................................................. 39
Beaver territories in Klosterheden State forest
and surrondings
A. Introduction
1. Presentation of the species : European beaver, Castor fiber
Linnaeus 1758.
1.1. Taxonomy
Beavers are semiaquatic mammals, they belong to the order Rotentia, the family Castoridae.
They are divided in two species : Castor fiber Linnaeus 1758, the European beaver and
Castor canadensis Kull 1820, the north-American beaver.
North-American beavers have got 40 pairs of chromosomes (following Robertsonian fusion of
eight pairs of chromosomes) while European beavers have got 48 (Lavrov & Orlow, 1973 in
Rosell & Sun, 1999 and in Hartman, 1994). Rosell & Sun (1999) found that colour and
viscosity of the anal gland secretion (AGS) could also be used for discrimination between the
two species.
Nevertheless, these two species are similar both morphologically and behaviourally. However
the North-American beaver has a greater ecological flexibility, survives better under severe
climatic conditions, adapts more easily to substitute foods, regulates hydrological regimes of
water body better and is more fecund than the Eurasian beaver (Danilov & Kan’shiev, 1983
and Hill, 1982 both in Rosell & Sun, 1999).
Castor fiber may also be divided in eight sub-species according to relict populations and
morphometric characteristics.
1.2. Body description and characteristics
Weight: 18-20 kg for 75-100 cm length. Short plump legs support the body. Its hind and front
feet have 5 digits with claws. The hind feet are webbed and the 4th claws form a comb, used
for grooming (Richard, 1980; Bau, 2001; Laanetu, 2001).
On land, beavers walk on all four legs but can also walk on their hind feet in a upright
position with the tail stabilising the posture (Carlson & Welker, 1976 in Bau, 2001;
Richard, 1980). They usually don’t walk very far from the shore.
As a semiaquatic animal, beavers have special feature; the most remarkable being their large
tail covered by scalelike skin with small bristle hair (Carlon & Welker, 1979 in Bau, 2001;
Richard, 1980). The tail is used as driving power, manoeuvring, diving while swimming (Bau,
2001). It also assumes a function in regulation of body temperature, body energy reserve and
defense against enemies (“tail slapping”) (Richard, 1980; Bau, 2001; Laanetu, 2001).
The fur is thick, formed by two layers which function as isolation when in water
(Richard, 1980; Bau, 2001; Laanetu, 2001). The nostrils are closeable as well as the opening
of the ears; and eyes are covered by transparent eyelids when beaver dives (Richard, 1980;
Bau, 2001; Laanetu,2001). Beavers can also shift the position of the epiglottis in order to
prevent water going into breathing ducts during chewing and transportation of timber under
water (Richard, 1980; Bau, 2001; Laanetu,2001).
Bearver territories in Klosterheden State Forest, Denmark
4
Diving time is 2-5 minutes normally but can extend up to 15 minutes (Rouland & al., 1984;
Richard, 1980; Bau, 2001).
Beaver dental formula is 1-0-1-3 / 1-0-1-3 (Rouland & al., 1984). As a rodent, the incisors are
constantly growing. The outside surface is covered by hard orange enamel.
Beavers present a pseudocloack where the urethra, the anus, the reproductive organs and two
pair of glands end up into. It is situated underneath the base of the tail. Castor glands produce
the castoreum. Mixed with urine, it is used to scent-mark on mounds of mud or plant material.
Secretion of anal glands serve on waterproofing the fur and also for scent-marking
(Richard, 1980).
No external criteria could be use to identify male or female. However males have a
bacculum (bone) which could be felt by touching the reproductive organ inside the
pseudocloack or seen by radiography (Richard, 1980; Rouland & al., 1984). Sucked females
are more easily recognizable, as teats could be seen passing from the fur (Richard, 1980).
Average longevity is 7-8 years but beavers can live until around twenty years.
1.3. Behaviour and ecology
Beavers have an active period during the night but in quiet places, they can be active during
daytime (Richard, 1980; Bau, 2001; J-C Gaudin, pers.comm.). Doboszyńska & Żurowski
(1983) reported that new born young are active in the lodge during daytime as their mother is
with them.
1.3.1. Reproduction and social group
Beavers are monogamous and live in family with an average of 2-7 members concerning
European beavers : an adult reproducing pair, young from last years and young of the years.
Sexual maturity is reached at the age of 1½ -2 years.
Beavers are polyoestrus from 1 to 5 oestrus during one single mating season (Richard, 1980).
The heat lasted from 12-24 hours. Mating usually occurs in January or February in the water
(Richard, 1980, Doboszyńska & Żurowski, 1983). However mating could be observed in
December, October or November (Richard, 1980).
Pregnancy lasts for 105-107 days and young beavers bear between mid-April to mid-August
(Doboszyńska & Żurowski, 1983).
Lactation in beavers lasts for 90 days but they begin to eat plant material as soon as they are
10 days old. The kids remain in the lodge the first 3-6 weeks (Richard, 1980, Lancia &
Hodgdon, 1983 in Bau, 2001).
All the family members take care of the new borns (Patenaude, 1983).
Dispersal of the young usually occurs at two years old and in spring. However, dispersal
could be delayed (e.g. Svendsen, 1989).
As an adult, beavers are totally under water when swimming, and only the head is up.
Rosell & Pedersen (1999) propose to evaluate age class according to the shape of the beaver
body in water.
Bearver territories in Klosterheden State Forest, Denmark
5
1.3.2. Foraging
Beavers are herbivorous animals. The main source of food is deciduous trees: bark, leaves,
shoots, buds and twigs. They also forage on herbaceous plants. Beaver diet has been studied
by many authors (Lapiński & Staliński, 2001; Borglykke, 2002; Svendsen,1980 and
Belovsky, 1984 in Borglykke, 2002). Populous (Populus sp.), willow (Salix sp.) and
birch (Betula sp.) are preferred.
1.3.3. Territory and building activities
Beaver territories are highly differentiated.
a. The shelters
The shelters are ground burrows or lodges but some intermediaries between these two states
could be found (Rouland & al., 1984). All have immersed entry from where an oblique
gallery opens out onto at least one room where the layer is. This room is often ventilated by
an open whole in the ground (Rouland & al., 1984).
- Ground burrows are dug by beavers where the banks are high and the soil soft
enough (Rouland, 1984; Bau, 2001). They may be overbuilt with branches especially when
the roof is collapsed (Rouland & al., 1984).
- Lodges are built where the cliff shaped banks are far away from the wateredge as
well as when beavers can’t dig in the bank (Rouland & al., 1984; Bau, 2001). The lodges are
built by accumulation of wood branches from feeding rest.
In springtime and summer time, beavers can use nests. These are depressions in the ground
located under bushes, a felled tree or tree roots (Bau, 2001).
Beaver colonies can use more than one lodge, especially in summer time (Richard, 1980,
Bau, 2001). A family inhabiting the same territory for a long time likely has several shelters
(Richard, 1980).
b. The dams
Dams are built with branches, grass and mud especially in stream habitats. They are used to
maintain a high water level around the lodge for keeping the entrance under water
(and therefore protected from predators), making easier swimming and transport of building
material (Rouland, 1984; Rosell & Parker, 1996 in Bau, 2001).
A waterlevel of at least 50 cm is necessary to provide a quick route for escape
(Macdonald & al., 1995 in Bau, 2001).
Beavers can also build dams to increase the waterlevel of streams and channels up to feeding
sites (e.g. Flynder Å; pers.obs).
c. The refectories and the feeding site
Refectories are places used by beavers to eat bark from the branches they have just cut. These
sites are located near the wateredge and the branches are accumulated on the bank or under
the water (pers.obs; Bau, 2001, Richard, 1980).
The feeding sites are more scattered in the territory and easily recognizable: cut trees are
shaped as a pencil tip and cuts have got a characteristic oblong section (Fig.1).
The different feeding sites are used continuously along the year according to season changes
in the availability of food (e.g. bark, leaves, shoots, buds and twigs).
Bearver territories in Klosterheden State Forest, Denmark
6
d. The food caches
They are a collection of branches and twigs non-barked located usually under water and
sometimes on the wateredge. These stocks are used during winter.
e. The passage way tracks
As beavers use the same way to go to the different feeding sites, they leave in the ground
or/and grass some tracks. These tracks are also found where beavers cross roads to go from
one water area to another (e.g. in Ællebæk, in Risbæk territories; pers.obs.).
Channels are dug in order to link to water area separated by a little way of ground, go across
river meandering and make easier swimming in swamp area or accessing feeding sites far-off
(Richard, 1980; Rouland & al., 1984).
1.3.4. Territory and scent-mark
European and North-American beavers are highly territorial and use scent-marking as a
means to territory defense and delineating family territories (Rosell & Nolet, 1997,
Rosell, 1994, Müller-Schwarze & Heckman, 1980; Rosell & Bergan, 2000,
Nolet & Rosell, 1994)
Scent-marks are mounds of debris material and mud or sand where beavers deposit castoreum
and/or AGS (Svendsen, 1980, Müller-Schwarze & Heckman, 1980, Rosell & Bergan, 1998).
Both sexes and all age classes (except kids under 5 months old) participate in scent marking
(Butler & Butler, 1979). However few differences exist as males scent-mark more than
females in summertime (Thomsen, 2001).
Scent-marking activity varies with seasons (Rosell & Bergan, 2000; Rosell & al., 1998;
Svendsen, 1980) with peaks during spring when dispersal of the 2-year-olds may occur
(Svendsen, 1980; Rosell & al., 1998). Rosell & Bergan (2000) found that the median number
of scent-marking is higher when near and during the oestrous than the non-breeding portion of
winter.
Rosell & Nolet (1997) didn’t observe a significant difference in the number of scent-markings
during their study.
Beaver families with close neighbours scent mark more often than isolated families
(Rosell, 1994; Müller-Schwarze & Heckman, 1980, Rosell & Nolet, 1997).
Scent-markings may concentrate near the territory limits (Rosell & Nolet, 1997;
Rosell & al., 1998; Rosell, 1994).
Some marks appear to be maintained frequently whereas some others don’t (Rosell, 1994).
Beaver respond to intruder scent-markings with aggressive behaviour (Rosell & al., 2000,
Müller-Schwarze & Heckman, 1980; Müller-Schwarze & al., 1983), with however some
difference in observed behaviour (Butler & Butler, 1979; Rosell & al., 2000). After the
response, the beavers were often observed starting to patrol the territory (Rosell & al., 2000).
Nolet & Rosell (1994) observed that beavers swim faster through a foreign territory than in
their own territory as well as they don’t spend time on river banks.
Transient beavers are often 2-years old, but they could be males temporarily leaving their
family lodge or adult females without young (Townsend, 1953 in Müller-Schwarze &
Heckman, 1980).
Bearver territories in Klosterheden State Forest, Denmark
7
Bau (2001) described scent-marking behaviour in Castor fiber as including pawing with the
front feet, placing the cloacae above the pile scraped together and depositing scent. Stamping
the hind legs on the pile for a couple of times could follow this scent-marking sequence
(Bau, 2001). Scent-marking behaviour lasted between 6 and 18 seconds (Bau, 2001).
2. Beavers in Denmark
Beavers used to live in Denmark but disappeared from the country for more than two
thousand years (Bau; 2001). In October 1999, 18 Eurasian beaver (Castor fiber) - 12 adults, 4
juveniles and 2 kids - from Germany were reintroduced in Klosterheden State Forest District
(north-western part of Denmark) in two successive releases (Asbirk, 2001; Bau, 2001). The
reintroduction area covers the upstream parts of the Flynder Å stream catchment area inside
the Klosterheden State Forest District (KLS). Beavers were released at six lakes where
artificial lodges had been previously built (Asbirk, 2001; Bau, 2001).
Rather quickly, the beavers have left four of the release sites and spread out in KLS and
surroundings (Asbirk, 2001; Bau, 2001; Elmeros & al., 2004). They have been breeding
successfully and the first young had been observed in August 2000.
The beavers have actually colonized the most part of the Flynder Å stream catchment area:
five territories are in KLS and eight on private owner lands outside KLS (Fig.2). The beavers
have settled in lake habitat as well as stream habitat.
Beaver tracks are also recorded in the river Storå (Elmeros & al., 2004; see also part B.4.2).
According to the last counting (April, 29th and 30th & May, 1st 2004), the population is
estimated at 52 beavers and 9 young are observed for 2003 (O.Olsen, pers. comm.).
In addition to an extensive monitoring program coordinated by the forest staff for the
reintroduction, two deeper studies were made in order to increase the knowledge of the novel
beaver population. Bau (2001) studied beaver behaviour during the settling phase using
infrared video recording equipment and beaver tracks recording on field. Borglykke (2002)
studied beaver diet using feces analyses.
Bearver territories in Klosterheden State Forest, Denmark
8
B. Beaver study
The aim of this work is to clarify some knowledge on the actual beaver territories and bring
out some more accurate information.
1. In Klosterheden forest district
1.1. Definition
A Territory is delimited between two tracks assessing a continuous beaver presence : scentmark, lodge and refectory in activity, dams. Natural limits as a main road were also used. A
freshly marked scent mound with a scent detectable by a human nose at 2 cm or more, was
termed scent mark. This also included marks directly on the ground or on tussocks
(Rosell & al., 1998).
In this part, Møllesøen, Ællebæk, Flynder Å and Hestbæk refer to a beaver activity area
unless when stated (Fig.3).
1.2. Møllesøen/Flynder Å
Møllesøen lake is the one chosen for reintroduction and therefore one of the oldest beaver
territories of Klosterheden plantation. At present, the beaver territory stretches from upstream
Abogård to Øvej.
Crossed by Flynder Å River, it is roughly composed of 3 parts:
- Reed mace swamp upstream Møllesøen;
- Møllesøen lake boarded by coniferous forest;
- Grass meadows with willow area downstream Møllesøen lake = Flynder Å.
With the artificial lodge built for reintroduction, two other lodges was found in this territory:
one on the third island of Møllesøen ; one downstream at the intersection of Flynder Å river
and a channel from the lake (Fig.3).
According to observations made during the annual count, the forest staff discusses the
possibility of having two beaver families and therefore two territories instead of one.
Boundaries would be roughly near the Gl. Landevej.
1.2.1. Material and methods
Territories were drawn during daytime by walking along the riverside of all territories
waterways and recording all signs of activity on a map. Cartography of Møllesøen territory
was made in late April. However, scent-marks were recorded around once a month for the
part between Gl. Landevej and Øvej and for the lake once again in August. As the waterfowl
monitoring (see part 2) took place on the easthern riverbank of the lake, the scent-mark found
there was summed up on the map (Fig.4).
Boundaries were studied in relation with scent-mark as beavers clumps scent-mark near
territorial borders (Rosell & al., 1998) for territories with close neighbours.
Observation point was carried out opposite to the first fresh supposed scent-mark i.e the
supposed boundaries (Point A & B - Fig.3).
Bearver territories in Klosterheden State Forest, Denmark
9
From mid-May to mid-June, observations were made from sunset and ended either when bad
weather conditions caused to be very low or when the equipment was insufficient.
No camouflage equipment was used. One observer carried out all observations.
Military night vision glasses were used (Photonic type NS-B 3.3-80) as well as infrared light .
However the infrared light system was abandoned, as it was inefficient.
No beaver was marked for individual recognition (Bau, 2001). Therefore beaver families were
determined according to their arrival way. Age class, duration, behaviour and swimming
speed were also recorded.
1.2.2. Results
No beaver was observed at the point A during all the observation time: 53h15 of observation
enclosed 3 entire nights. However a possible tail slapping was heard once around 1 o’clock
downstream in the Flynder Å.
No beaver was observed at the point B during all the observation time : 30h of observation
enclosed 3 entire nights plus 2h made by a other observator.
1.2.3. Discussion
Brady & Svendsen (1981) noted during their study on American beaver that the male patrol
the entire perimetre of the pond at the beginning of each activity period. If distrubed, it would
return to the lodge (for up to one half hour). When it would reemerge it would carry on the
parol of the pond from the disturbance site.
I did not observe this behaviour during my watching. During the entire night, it blew
sometimes and this may have brought the odour to the beavers. Furthermore, I may have been
too noisy as the shelter was moving with the wind. However there has be some watching
without wind and without shelter. I did not observe a beaver neither.
The observation point was chosen as beeing a possible boundaries. We expect beaver to scentmark each night on their territory boundaries according to an abundant litterature. Therefore,
we assume that they scent-mark in all the scent-mark place of the boundary. They didn’t.
They seem to scent-mark once in a couple of days at a given place. As the scent-mark making
is very quick (from 6 to 18 second (Bau, 2001)), it is lucky to see the beaver scent-marking in
a given point on the boundary. This, indeed don’t exclude that beaver do spend a lot of time
on their boundaries.
If they do patrol the territory each night, and if Flynder Å and Møllesøen had been one
territory, I must have seen a beaver pass before the point A. I have not. Therefore, Flynder Å
and Møllesøen must be two different territories. The scent-mark pattern shows that the place
chosen for the watching have got a permanent scent-mark except for August when the water
has flotted the place. However they managed to scent at the other place downstream (Fig.4).
In Øvej, they uphold the scent-mark during all the study period. When the water level
increased in August they managed to scent-mark little heigher with sand or grass as the
riverbank lend itself to. For the same reason than above, Fynder Å and Ællebæk must be two
different territories.
To conclude, two family inhabit there: Møllesøen territory is reduced to the lake and Fynder
Å territory stretches from Gl.Landvej to Øvej (Fig.5).
Bearver territories in Klosterheden State Forest, Denmark
10
1.3. Ællebæk/Hestbæk
Hestbæk territory stretches from Øvej to upstream the fishery and covers both Ællebæk and
Hestbæk. Only one lodge has been recorded in this area (Fig.3).
According to observations made during the annual counts, the forest staff discusses the
possibility of having two beaver families and therefore two territories instead of one i.e
Ællebæk and Hestbæk. Boundaries would be on the river Flynder Å.
1.3.1. Material and methods
Territories were drawn during daytime by walking along the riverside of all territories
waterways and recording all signs of activity on a map. Cartography of Ællebæk was made in
late April. Searches of lodges in Ællebæk were made in April and July. Area between
Gl.Landvej and Jagtvej were prospected in June and between Jagtvej and Tårnvej in July by
following the streams and the bank of the lake.
Scent-marks along the river Flynder Å were recorded in April-May, July and August for the
part downstream Øvej.
Boundaries were studied in relation with scent-marks as beavers clumps scent-mark near
territorial borders (Rosell & al., 1998) for territories with close neighbours.
Observation point was carried out in different parts of the area (Fig.3).
No camouflage equipment was used. Military night vision glasses were used (Photonic type
NS-B 3.3-80).
1.3.2. Results
Until June 20th at least seven beavers inhabited this territory with at least 1 young. According
to the observation made at the point C (enclosing two entire nights), some beavers sleep and
spend daytime in Ællebæk but no resting place has been found yet. However some beavers
sleep and spend daytime somewhere else. Some beavers were seen crossing the road from
Ællebæk to Flynder Å river late in the morning (around 6 o’clock) and didn’t come back
(at least in the observation time). During Summer, the first beaver has been seen more often
crossing the road from Ællebæk to the river Flynder Å. A collapsed burrow was found along
the Flynder Å just downstream the point D.
Observations made in point E confirm that the beavers use the lodge in Hestbæk.
Beavers were observed alone, swimming upstream to me when I was watching from point D.
They could have stopped and disappeared from view. Sometimes, I heard some eating noise.
I found eating tracks in site 1 while a dam flotted the area behind. When beavers passed
before me, they disappeared from view.
1.3.3. Discussion
As said above, a boundaries is assessed on Øvej between FlynderÅ and Ællebæk/Hestbæk.
According to the data, Ællebæk could not be discrimated from Hestbæk as a territory for itself
(Fig.5). A beaver family can use more than one lodge or burrows and especially in summer
time (Richard, 1980; Bau, 2001). The fact that beavers have a resting place in Ællebæk is not
enough satisfactory.
Beavers seen swimming alone upstream to Ællebæk (at point D) must be members of
Hestbæk as the closer family downstreams lives far away after the fishery (U2). Therefore,
Hestbæk family use both sides of the river (Fig.5).
Bearver territories in Klosterheden State Forest, Denmark
11
The important scent-marking on the riverbank downstream Øvej (Fig.4) could be explained as
this part is a necessary downstream dispersion way for the 2-years old from the two family
upstream. Indeed most of the scent-marks were found in April-May just before the 2-years old
dispersion.
Ællebæk is a bush area with many willows while Hestbæk is a common reed swamp more or
less flotted where the bushes are inside the vegetation and therefore less easy to reach.
As I have never seen a beaver at the bundary on Øvej, it is impossible to tell which family
(Flynder Å or Hestbæk) uses this area. Therefore I stopped the territories before the bridge. In
early setpembre, I found a new cutting tree and fresh eating tracks there.
The beavers visit sometimes Ællebæk Sø but have not setlled any territory there. Indeed just a
few fresh cuts were recorded near Ællebæk Sø and close to Jagvej. However no cuts or tracks
were found between Gl.Landvej and Ællebæk Sø. Most of the tracks near the lake were old
and may date from the reintroduction. Therefore I limited the beaver territory at Ællebæk
where the last beaver tracks have been found (i.e scent-mark, dams and refectory).
1.4. Discussion on the methodology
1.4.1. Record of scent-mark
A scent-mark is easy to recognize as the smell is very characteristical. Beavers can scent mark
also with AGS (Svenden, 1980, Müller-Schwarze & Heckman, 1980, Rosell & Bergan, 1998).
I have considered only the scent-mark with castoreum as we didn’t know the smell of
the AGS.
The April-May record was made with a low level of water and a low vegetation. Afterwards
the water level increased with a maximum for the August prospection. The vegetation have
grown up on the riverbank first, and inside the river in a second time (especially for
burreed (Sparganium erectum)). The August prospection has been made from inside the river
because the vegetation was too abundant.
I may have missed some scent-mark especially where the riverbank is covered by trees and
bushes (i.e. western part of Møllesøen, Ællebæk).
Some scent-mounds were also found without odor anymore and therefore non-recorded on
the map.
Some scent-marks are uphold along the time whereas the others are only made once or twice
(Fig.4). This is in accord with Rosell (1994).
Scent-mark recording is the most important process with radio-telemetry when studying
beaver territory (Rosell & al., 2000; Nolet & Rosell, 1994 (for the old territories),
Rosell & Nolet, 1997; Rosell, 1994; Borgykke, 2002).
The beaver territory study focusing on observation only is possible. It needs a lot of time and
an efficient material. With the use of infrared video, this work could have been made more
quickly and without doubt. Furthermore, this method would have avoided the problem of the
odour and noise from the observer. Indeed it is more expensive and not necessary in this case.
However the next study could be thinked of under this way.
The markings of the individual have not been chosen because of the death factor. However
the popualtion has grown and telemetry study would be envisaged in a few years. By marking
the 2-years old, dispersion could be studied as well as territory boundaries when the 2-years
old would settle their own territory. Pair formation and duration would be also studied this
way.
Bearver territories in Klosterheden State Forest, Denmark
12
This could also bring a solution for the dead recorded, because many of the transmittors could
have different signal when the animal is dead (Ouellet, 1999).
Furthermore, an indice of population growth could be settled between the marked individual
and the non-marked individual so the population size would be known too.
1.4.2. Night vision glasses observation
With a night vision glasses system, all is seen in a green color more or less bright. The
vegetation and ground is quickly mixed up when dark and the point of reference more or less
lost. The best use was at point C where the road offers a good contrast.
Like common glasses, there is no use possible with fog.
Difference between grown-ups and young are difficult to make and have been made
satisfactory only when together.
2. Beaver population estimations
2.1. Introduction
Population estimations for beavers has not been found yet: neither lodge building
(Ouellet, 1999) nor food caches (Osmundson & Buskirk, 1993) seem be usable. Furthermore
the abundance of scent marks varies along the year (Rosell & Bergan, 2000; Svendsen, 1980;
Rosell & al., 1998) and with the number of close neighbouring (Butler & Butler, 1979;
Müller-Schwarze & Heckman, 1980) and therefore can’t be used. Beavers inhabit the same
territory for several years (Richard, 1980). For this reason, eating tracks should increase with
years even if the size of the colony doesn’t change. Furthermore eating tracks vary according
to seasonal food abundance and beaver activity. Therefore, eating tracks seems to be a bad
choice for population estimation.
In order to estimate the beaver population in Klosterheden and surroundings two yearly
beaver counts were organised with 30-40 participants observing beavers during two evenings
and two mornings in April and October since the reintroduction.
Data from all beaver counts were analysed. The aim of this work is to bring out a pattern in
beaver observation and reduce personnel and/or observation time for the beaver count.
In the following part, the words “observation” refers to a sight of beaver, the words “watch”
to a watching of a part of a beaver territory during a period of time when an observer may
have seen none, one, or several beavers.
2.2. Material and methods
2.2.1. Characteristics of the observation during beaver counts.
Data were sorted out according to observation characteristics as age class of the beaver
observed (i.e. adults or juvenile) and period when observation was made (i.e evening or
morning) (Tab.1; Fig.6 & 7).
The number of observation points has increased with years according to the increase in the
beaver population and its dispersal. Furthermore, all the observation points were not supplied
for all the observation periods through a given count. The number of made watches was
calculated for each beaver count and inside each observation period (Tab.1).
Bearver territories in Klosterheden State Forest, Denmark
13
An index “observation number/watch number” was calculated in order to compare the
different periods of counting (Fig.7).
For the kid seen in October 2000, no period has been noted. Therefore we divided the number
of juveniles by two and assess the result to each period.
In a second time, data were sorted out according to the hours of observation (before/after
sunrise/sunset) (Tab.2; Fig.8 & 9). An observation beginning before sunrise/sunset and
finishing after, counts for one observation before and one after. This is the only case where
duration of the observation was considered. If the observation is noted as made when the sun
goes down/up, the observation counts for one observation before and one after. Two
individuals observed in the same time count for two observations.
Only the data with an hour noted could be use.
Lots of parameters are unsettled (numbers of territories, posts, observers...). Statistical
analysis could not be applied with efficiency and therefore was not used. Data were analysed
graphically with the Microsoft Excel® software.
2.2.2. Hypothesis on different methodologies for beavers count
Actually beaver counts took place twice a year, in spring and autumn. Two days are used to
observe the beavers during 1 hour in sunset (30min before, 30min after) and 1 hour in sunrise
(30min before and 30min after). The beavers are counted at counting zone where only some
of them fit with the beaver territories. This work is almost entirely made by volunteers.
The young are considered according to information on the breeding in each counting zone.
This knowledge corresponds to the beaver kids seen out of the counting period.
The maximum number of juveniles per territory is known when several kids are seen together.
Dead beavers subtracted. Dead beavers are all the beavers which dead bodies have
been found.
Data covers counting from April 2000 to April 2004.
Different kinds of counting were simulated according to the data:
- One day of counting twice a year (i.e spring and autumn);
- Two days of counting and 1 counting season (i.e spring or autumn);
- One day of counting once a year (i.e spring or autumn).
Any possible combining between data were analysed.
Data obtained with the present methodology (i.e two days of counting and two
counting seasons) are took as basis (100% of information) for the percentage calculation.
2.3. Results
2.3.1. Characteristics of the observation during beavers count.
Beavers are observed as often in the morning as in the evening. However, more beavers have
been observed in the morning until now (Fig.6). Age class may play a role in beavers
observation: adults were observed especially during morning counting whereas juveniles were
during evening counting.
However no pattern can settle as the trends could go in the opposite direction according to the
beaver count (e.g. April 2003, October 2003) (Fig.7).
Bearver territories in Klosterheden State Forest, Denmark
14
Sun hours may play a role in beaver observation. Evening observations (µ=0,67) are made
mainly after sunset (Fig.8). Morning observations (µ=0,61) have been made before sunrise
and especially during the four last count (Fig.9).
2.3.2. Hypothesis of other methodology
The results are presented without subtracting the dead beavers unless when stated (Tab.3)
- One day / 2 counting seasons
128 combinations could be found. As they are redundant, only 10 solutions exist finally for
the estimation of the beaver population in this case. They spread out from 43 to 52 beavers
but each possibility doesn’t have the same chance to be found.
- One day / October counting
6 solutions could be found. As they are redundant, the beaver population could be estimate
at 37, 38 or 39 beavers with respectively 33,33%, 50% and 16,67% to be found.
- One day/ April counting
Fore solution could be found with the same chance: 41, 42, 43, 44.
The percentage of conserved/lost information varies with the kind of information
(i.e. beavers). However, they follow the same pattern (Fig.10).
2.3.3. Personnel featuring
Number of observation points and number of watches increased with the growth of beaver
population. This went with an increase in personnel featuring. However, all the observation
points were not supplied for all the observation periods through a given count. In average;
86% of the observation points are supplied during the four counting periods of a beavers
count. The ratio “number of personnel/number of observation points” is more than 1 (µ=1,38).
Therefore, all the personnel did not participate during all the beavers count.
2.4. Discussion
2.4.1. Characteristics of the observation during beaver count.
Bau (2001) found that beavers in Klosterheden showed no pattern for their first appearances.
However the first sighting had an average of 78 minutes after sundown (Bau, 2001). Even if
the study was carried out at the beginning of the reintroduction time and only in few families
(as well just one family could be monitored with the help of video recording), data from
beaver count follows a similar pattern as the beavers are more often seen once the sun had
disappeared. However, in the morning, beavers could spend a lot of time after sunrise outside
their lodge (personal observation), this could explain the observation made in April 2001 and
April 2002.
Beavers show no significant preference for one of the periods (i.e morning or evening). The
tendency showing in Fig.6 should be considered with reservations as they could vary (Fig.7).
Furthermore, a coincidence inside the data could not be remoted because most of the
parameters are not settled around the counting period (from 2001 to 2004). One of them could
have an influence.
Bearver territories in Klosterheden State Forest, Denmark
15
2.4.2. Hypothesis of other methodology
Changing the counting method will cause loss of information. However two methodologies
could be seriously envisaged as the loss is less than 15 % on the estimate of the population:
one day with two counting season (A method) and two days of counting made in April
(B method) (Tab.3).
The A method is more efficient but the B method would be more economic. Indeed, lots of
participants don’t work in the forest and several of them come from Copenhagen. It will be
less expensive to come here for two days once a year than one day twice a year.
Furthermore, the efficiency of the A method could be dued to an effect on the data
combination. Indeed, most of the juveniles have been observed just once during counting days
(Fig.11).
April counts are more efficient than October counts even if there is more people per
observation point for October counts (for all the counting season). This is due to the fact that
the beavers seen in October are often seen once more in April. For all the counting season,
sights of beaver juveniles are more important in April (µkids sight in April >µkids sight in October)
There is less vegetation and more light in April than in October. Therefore the conditions of
observation are better. Other explanation could be in relation with the weather as the
temperature is generally lower in October than in April. Beavers spend less time outside the
lodge in winter, as the water temperature is cold.
An another explanation could be found in the young beaver’s behaviour. In early October,
young beavers have only a 2-month experience outside the lodge. The first young are mainly
seen in early August. In April, they are older and more experienced. Therefore, they may
spend more time outside the lodge and will be seen more easily.
2.4.3. Analysis of the actual methodology of counting
a. Overestimation argument: Recording of dead beavers.
Dead beavers are taken away from the population only when a body has been found. For the
moment, only two dead beavers have been taken away.
In the two cases, private individuals transmitted the information to the staff forest.
The forest staff was called for dead beavers many times but it was rarely a beaver. Mixing up
with otters is the general case but it can be with all sorts of animals, even a roe deer
(O.Olsen, pers. comm.).
Not all the dead beavers could be found, as all the wateredges cannot be checked all the time.
Furthermore, many beaver territories are on private owned land and some without any close
inhabitant around. Therefore, the dead beavers cannot be recorded easily. The body would
drift but the possibility that it will be found is also low if it drifts in an uninhabitated portion
of river.
Average longevity is 7-8 years but beavers can live until around twenty years.
Five of the reintroduced beavers were more than 51/2 years-old when released in October 1999
(Bau, 2001). Four years and a half later, these individuals have passed over the average
longevity and may have died. Seven reintroduced beavers were between 2 and 51/2 years-old
and some of them have passed over or have just reached this average longevity too.
Therefore, the population may count at least 3 beavers less.
Bearver territories in Klosterheden State Forest, Denmark
16
Consideration of the death factors.
The predation must be very low in Denmark as neither wolves, bears, nor lynxes live in the
surroundings of the release site. Otters have been reported to prey on beavers whereas red
foxes, minks and fishers (Martes pennanti) are known to prey on American beavers
(i.e. Collen & Gibson, 2001). However, they are not considered as regular predators.
Furthermore only the otter is well represented in the area but it eats preferentially fish.
Humans play an important role in beaver populations as they destroy their habitats.
In Denmark where the beavers have been especially reintroduced for creating wetland
habitats, it is more the lack of suitable habitats which should be considered. This will be a
limiting factor for the population increase more than a death factor.
Destruction of dams and lodges especially during winter could bring out beavers to death if
they don’t find a new suitable place.
For the moment, only a few dams have been removed on private owned land by the
forest staff.
In the forest, a pipe has been put under Øvej to avoid the flooding of the road but the beavers
are now used to cross the road. Hopefully the road is forbidden to public circulation and only
used by the forest staff.
Road kills are recorded as a death factor in beaver population (examples referred to in
Bau, 2001, Rouland & al., 1984).
This factor must be considered in Denmark as a car hurt a beaver, a few days after the
reintroduction. In this case the beaver was able to be cured and released in nature after.
For the moment, no poaching has been recorded in Denmark but it is a death cause in other
countries. With the growth of the population, hunting has already be suggested and poaching
may come too.
Beavers suffer of intestinal tract disease, pseudotuberculosis (Rouland & al., 1984, Bau, 2001)
and parasitism (Rosell & al., 1996 in Bau, 2001). Only rabies and tularaemia has not be found
yet in Denmark and blood samples of the reintroduced beavers were analyed before the
reintroduction (Asbirk, 2001; Bau, 2001).
Extremely cold winter and heigh swelling have not yet be recorded in Danemark.
At last, interspecific competition and fights between males can cause death especially in
dense population. In Denmark, the population could not yet be considered to be dense but
fights may occur anyway between dispersed individual and residents.
Furthermore, it seems luckiest if all the kids reached the adult size even if the kids mortality
in beavers is low.
b. Underestimation argument: Recording of the new-born kids
The risk of overestimating the breeding is low as the additional beavers are considered only if
several kids are seen together. Moreover, kids are seen often just once through a counting
period (Fig.11) and mixing up with kids is rare. It can happen especially in Hestbæk where
the territories enclose three counting zones. In this case, details of the observation helps to
assess the number of young.
Bearver territories in Klosterheden State Forest, Denmark
17
The risk of underestimation is more important.
The litter is 2-4 kids in European beavers with an average of 2,7 (Salvesen, 1927 and
Danilov & Kan’shiev, 1983 in Bau, 2001).
In Denmark, most of the litter have been observed with only 1 kid (47% of case) and some
families have never breeded yet (Tab.4)
In 2002, four 1 year-olds have been seen and did not correspond to the data on the breeding
in 2001. Therefore, they haven’t been seen as kids and were summed afterwards.
This proves that all the kids are seen neither during the counting nor during another period of
the year.
As an other example, 3 adults were recorded in Fruerbæk in September 2003 but neither kids
nor 2 year-olds were recorded there.
The breeding must be underestimated.
Conclusion: Considering one and the other, it may find a balance and therefore the counting
gives a good idea of the population estimation.
2.4.3. Index on number of territory.
When the 2 years-old leave the lodge, they go find their own territory and pair mate to build a
family. The number of territories should follow the variation effectif inside the population
with a delay of roughly two years.
Assessments: All the 2 year-olds disperse during their 2 years. Two beavers will live in a
territory and form a pair (therefore the sex ratio is assumed to be equal to 1). The number of
territories is known according to the place where the counting has been taken place and
information reported in Elmeros & al. (2004).
Only 2 kids under 1 year-old were release in October 1999 (at Møllesøen) but four individuals
between 1-2 year-olds were release as well (Bau, 2001). The first dispersion should begin
during 2000 whereas the kids released in Møllesøen may have disperse in 2001.
Until 2001, seven territories were settled: Hestbæk, Risbæk, U1, U2, U3, U4, U5 while five of
the release site were left: Stenbæk Sø, Rørkær Sø, Ellebæksøern, Rishøj Sø, Neder Sø.
Møllesøen is the only release site where the beavers have settled a territory. This is also the
only site where a family unit was conserved with a pair and kids from this year.
During all this reshapes, two new family unit appeared.
But with 6 beavers in dispersion, it misses at least one territory. In fact, a beaver in dispersion
can find a place in a previously settled territory where the reproductive pair is broken.
Svendsen (1988) found that mate-turnover happens frequently during a beaver life. Death of
the mate is the main cause but desertions of the family have been also recorded (4% of cases).
The territory could also not be recorded as it was not settled yet and the individuals always in
dispersion or not be recorded because no found. The young at Møllesøen could have also
delayed their dispersion for some reason. Svendsen (1989) found that the dispersion is
delayed in dense population area. It was obviously not the case but the reintroduction and
settlement in a new place could have perturbated the kids.
In 2002, two new territories were found (Fruerbæk and U7). However, U6 and U8, found in
early 2003 (winter), could descend from the dispersion during 2002 as 2 years-old dispersion
occurs normally in spring time.
Bearver territories in Klosterheden State Forest, Denmark
18
In 2002, the young from the first breeding in Denmark (in 2000) reached the time of
dispersion and 6 kids have been recorded in 2000. By making pairs with individual, there is
one territory too many. It could correspond to the territory not found for 2001. However, not
all family units are composed by a reproductive pair with kids (Richard, 1980). This is
reinforced by a sex ratio which may not be equal to 1.
After March 2003, no new territory was recorded but ten kids were noted for 2001 and must
be in dispersion. Several tracks were recorded along the Storå: cut and fallen trees and sights
of beavers, but neither lodge nor dams were found. In fact, nothing permited to know if it was
the same beaver, which was swiming in all places or if several beavers made the different
tracks.
In 2003, the second lodge in Møllesøen territory was built (Elmeros & al.; 2004) downstreams
the lake. As we assess now that it is a new territory (i.e. Flynder Å see part 1.2), therefore it
may be a territory descending from the dispersion during 2003.
The stagnation in the number of territories until 2003 could therefore have two principal
explanations :
- the replacement of a lost mate inside a settled family unit (and therefore a underestimated
death record);
- the not-yet recorded new territories.
However, the variation in the number of territories seems to follow the variation of the
population (Fig.12).
To use such an index, it will be important to decide which tracks are significant of a territory
settlement: active lodge/burrows, dams and scent marks can be chosen.
However, dams are not built if the water is enough high. Burrows are difficult to find if they
are not overbuilt by branches and the entrance kept under the water surface, as it must be.
Scent-mark is the most important tool for drawing beaver territories (Rosell & al., 2000;
Nolet & Rosell, 1994 (for the old territories), Rosell & Nolet, 1997; Rosell, 1994;
Borgykke, 2002) but their record needs to spend a lot of time along the wateredge. Walking
along the wateredge is not always possible as most of the area is a private owned land and/or
full of grass. Regular observations of beavers in an area can also serve to assess the presence
of a territory.
Now that the beavers disperse outside the forest, all the information will depend essentially on
private people.
As for dead beaver recordings, not all the area can be checked and some of it is uninhabited.
Until now, it works but such a dependence could be a problem in a few years, when people
will be used to the beavers.
Another problem will come when the beavers are leaving the territory forever. The recorded
of abandoned territories could be delayed in time if the lodge/dam is not destroyed quickly.
Furthermore, this does not correspond all the time to an abandonation as a family could use
more than one lodge, or build/dig a another shelter. Broken dams are not always a sign of
deserted area (e.g. Flynder å). To rebuild a dam could take a lot of time (more than one
month) (Flynder Å, pers. obs.). Obviously, the scent-mark will disappear as well as regular
sight of beaver in the area but they are both time-costing methods.
Bearver territories in Klosterheden State Forest, Denmark
19
In the next two years, it will be interesting to see if the number of territories will follow the
pattern of the kid records (Fig.12).
Recommendation.
After the age of ten, beavers could be taken away from the population.
However if the non-recorded deaths correspond to non-recorded kids, this will cause an
underestimation of the population. A survey on the reproduction is needed, to know the
potential breeding of the population and a reliable fecund rate, as they are very low until now.
(See part 1.5 for argument on radio-marking).
In order to change the counting method, April count (A method) should be tested. As we
bring it on data from all the previous countings, we cannot assess that the lost information will
not grow up with the population increase. If such a relation is not settled, April count should
be applied for counting.
In Germany, Dr. Heidecke used a method of mapping territories/lodges and multiplied by 4
individuals (S.Asbirk, pers.comm.). As the index of territories follows the variation in
population estimation (part 2.3.4) and as doing the same in Klosterheden, we get the same
population estimates as with the beavers counts (S.Asbirk, pers.comm), I think this method
could be considered for the future.
However, with marked beavers it would be easier to map the territory without any doubt.
3. Outside Klosterheden state forest
3.1. Investigation along Storå river
The Storå river runs south from the Flynder Å catchment area.
Beaver signs were found on Storå : several branches were cut at the intersection between
Storå and Ellebaek and upstream from Vemb. Direct observation of beavers took place in
Holstebro and on October, 1st upstream from Vemb. However, the forest staff wasnn’t be sure
about the first observation.
Investigations made until now have not established a permanent beaver presence on Storå:
beavers evidence being less significant. Therefore, beaver territories on Storå remain to be
proved.
3.1.1. Material and methods
Investigations were made by canoë from Holstebro to Vemb. Each riverside was observed
simultaneously and randomly by two observers. In this way, one investigation was made on
April 6th.
From Vemb to about 100m before the river mouth, investigation was made using a little
motorized boat. Three observers looked at one bank during the way down and the other bank
during the way up. In this case, one investigation was made on April 7th.
3.1.2. Results
From Holstebro to Vemb, no beaver signs were found. Four beaver signs were found near the
mouth in a section of roughly 1km long. It was cuts of few little branches and two barked
branches lied on the ground. Signs were recent, in regard of their light and unoxydized colour.
Bearver territories in Klosterheden State Forest, Denmark
20
3.1.3. Discussion
Investigations of April 6th and 7th were made after a raining period. Therefore, the water was
brown owing to streaming and the water level was high. This bad visibility condition didn’t
permit to bring to the fore of possible burrows. Even high bank could be a good place to dig
burrows, habitat is favoured to beavers especially after Vemb, where deciduous trees areas are
more important.
This could explain the lack of tracks from Holstebro to Vemb.
Beaver signs founded are in few number and not significant of a territory settlement (unlike
burrows, lodge, dams and scent-mark). On the other hand, it proves way of beavers and a
fortiori Storå could be seen as a colonization way for beavers.
Furthermore, dispersal of the 2-year-olds beavers took place during spring, and few founded
signs could mean that dispersal has just begun.
Tributaries and streams have not investigated yet. The possibility of a beaver territory
somewhere in this region persists.
3.2. Search for the lodge in Flobæk
The area is situated on a private owner land, and cows feed on the fields on both sides of a
river. The river sides are sloppy and therefore protected by a fence.
The burrow the beavers have built there collapsed. No other shelter has been recorded for this
time but eating tracks still spread along the area.
3.2.1. Method
Search of the lodge has been made by walking along the riverside. The investigation took
place in late July.
3.2.2. Result
No lodge has been found. Two ventilated wholes have been found in the ground.
3.2.3. Discussion
The ventilated wholes could be assigned to many things. I was not able to see under the water
if an entrance had been dug. The water was too dark as it was after a raining period. The
eating tracks were few and concentrated along the first field (i.e. closer form the house).
However the cover of tree was low and therefore the tracks less easier to find.
Not all the riverbank could have been checked.
Bearver territories in Klosterheden State Forest, Denmark
21
Monitoring of water birds in the beaver ponds
A. Introduction
After the reintroduction of European beavers Castor fiber in Klosterheden state forest district
in Denmark, waterlands areas have increased thanks to the beavers building activity and the
flooding of their territories. Bird breeding was monitored from 2000 to 2003, especially for
the sparrow species (Elmeros & al., 2004). However waterfowl breeding was less studied. The
aim of this work was to monitor a breeding season on beaver territory and therefore to assess
the impact of beaver introduction made three years before.
B. Material and methods
1. Study area
Klosterheden State Forest (KLS) is situated in the western part of Juland (56°28’N, 8°20’E),
Denmark. It is a mixture with coniferous plantation and heath area, covering approximately
7000 hectares. Forest raisings, meadows, beaches and small forests are also present on the low
area (Borglykke, 2002). Coniferous trees species as sikta spruce (Picea sitchensis),
scotch pine (Pinus sylvestris), common spruce (Picea abies) and noble fire (Abies procera)
dominate the forest area (Borglykke, 2002). Deciduous trees species as birch (Betula sp.),
alder (Alnus sp.), willow (Salix sp.) and aspen (Populus tremula) are present only in few
percentage (Borglykke, 2002).
Flynder Å water system crosses the area with a low stream but before the reintroduction,
some of its have been dammed to create small lakes or ponds (rapport de reintroduction).
12 areas in or surroundings Klosterheden plantation were studied (Tab.5). This enclose all the
beaver territories present in this areas (i.e. Møllesøen, Flynder Å, Hestbæk, Ællebæk,
Fruerbæk, Risbæk, U1 and U2) and four control zone (i.e. Øvre Sø, Rishøje Sø, Ællebæk Sø
and Tårnsøen) where the beavers are not recorded regularly and therefore supposed to
represent the general breeding pattern for waterfowl in KLS (Fig.13).
Since May 30th, Stenbæk Sø was added to the monitoring.
Description of the vegetation
Algae have not been identified but they are present in all places.
Møllesøen : North-east/east river bank is a mixture of water plants (Acrocus calamus, Iris
pseudacorus, Sparganium erectum, Typha latifolia), sedges (Carex paniculata, C. rostrata),
various grass (Epilobium sp., Rumex hydrolapathum, Filipendula ulmaria), wild angelica,
nettles (Urtica dioica), lotus, water Forget-Me-Nots (Myosotis scorpioides), vetches
(Vicia sp.), joncus (Joncus effusus, Joncus conglomeratus) and a few willows. In the northern
part, it becomes a reed swamp with reed maces (Typha latifolia), common reeds (Phragmite
australis), great water docks (Rumex hydrolapathum) and sedges (Carex sp.) where the
Flynder Å runs with meandering. The western river bank is invaded by reed maces and
various decidious trees. The sounthern river bank presents less diversified vegetation than the
Waterflow breeding in Klosterheden State Forest, Denmark
22
northeast part and leads to some resting places. The Flynder Å leaves the lake there in two
running streams which meet a few metres downstream. A third stream run under the restingplace through a pipe and lead to a stagnant place invaded by the water vegetation
(Sparganium erectum and Lemna minor).
The water of the lake is largely covered by aquatic plants (Persicaria amphibia and
Potamogeon natans) and dispersed burreeds (Sparganium erectum). There are also some
“forest” of horstails (Equisetum fluviatile), patch of bulrushes (Scirpus lacustris), and/or
Acrocus calamus. Water plantain (Alisma plantago-aquatica) is also recorded as well as
Lemna minor. The first island is covered with reed maces, Epilobium, great water docks and
burreeds but the other Møllesøen’s islands have got more diversified grass patterns with
deciduous trees.
Flynder Å (monitored part) : The iver bed is invaded by burreeds (Sparganium erectum),
with iris (Iris pseudacorus) and reed maces. The sloping river banks are enclosed
(Lotus penduculus), nettles (Urtica dioica), water Forget-Me-Nots (Myosotis scorpioides),
Epilobium spp, Gallium spp. and rare trees (Salix sp).
On both sides spread out wet meadows with joncus species (Joncus effusus).
Lesser duckweeds (Lemna minor) spread out along the water. Canadian pond weed
(Elode canadensis) forms some underwater carpet especially before and after the monitored
portion.
Ællebæk : the dam have flooded forest swamp dominated by willow with bog myrtle
(Myrica gale), purple moor-grass (Molinia caerulea), common reed (Phragmite australis) and
sedge. This vegetation spread out in the western side before lead on the coniferous forest. The
water plants are represented by Lesser duckweed (Lemna minor).
Hestbæk : The dam is situated on a reed swamp area dominated by common reed
(Phragmite australis) with bog myrtle (Myrica gale), willow (Salix sp.) and meadowsweet
(Filipendula ulmaria). Great water dock (Rumex hydrolapathum), sedge (Carex paniculata)
and Joncus effusus are also present.
In the water, lesser duckweed is the main species.
Fruerbæk : The water has spread out in a moor scrubland of willow (Salix sp.), bog myrtle
(Myrica gale) with bog blueberry (Vaccinium uliginosum), joncus species and very few trees
(Popolus tremula, coniferous sp.). On the south-eastern part, it is followed by a grass meadow
(Deschampsia flexuosa, Molinia caerulea) with heather (Calluna vulgaris, Erica tetralix), and
common crowberry (Empetrum nigrum) whereas in the north-eastern part, the grass meadows
are more diversified. The coniferous forest is just behind.
Lesser duckweed (Lemna minor) is scattered over the water surface.
Risbæk : The first dam is dominated on both sides by bog myrtles (Myrica gale), purple
moor-grass (Molinia caerulea) with more or less deciduous trees (willow especially in the
eastern part, and birches especially in the western part). The wateredge is bordered with
Joncus effusus and grass. In the water, European frog-bits (Hydrocharis morus-ranae) and
cutleaf waterparsnips (Berula erecta) are found as well as a few burreeds.
The second and third dam are surrounded by wet meadows dominated by Joncus effusus.
There, burreed is well represented with some European frog-bits (Hydrocharis morus-ranae)
and Lesser duckweeds (Lemna minor).
Waterflow breeding in Klosterheden State Forest, Denmark
23
U1 : The monitored dam is a flooded area between forest and swamping meadow with
Joncus effusus and various grass, bordered by mace reeds (Typha latifolia) and burreeds
(Sparganium erectum) which scattered also in the dam. Lesser duckweed (Lemna minor) is
well represented especially in the swamp meandering.
It belongs for a part to a private owner area.
U2 : The lake is situated on a private land and a fishery spreads out on the Flynder Å from the
southern-east to the northern-east side of the lake.
The eastern and the western bank belong to a wet meadow more and less flooded with highly
diversified vegetation. It is dominated by grass (Phelum pratense), meadowsweet
(Filipendula ulmaria), Joncus effusus, Joncus articulatus and Rhinanthus serotines. Closer to
the water, reed maces and sparganiums (Sparganium erectum) scattered out. The eastern bank
is bordered by birch (Populus sp.) and few willow (Salix sp.) whereas in the western, common
reed domines. An island in the eastern water area is covered by reed maces and sedges.
European frog-bits (Hydrocharis morus-ranae) and Potamogeon natans cover most of the
water surface. Inside the closer dam, Lesser duckweeds (Lemna minor) and cutleaf
waterparsnips (Berula erecta) have been found.
Øvre Sø : The south bank is separated on Øvrevej by a small willow which branches fell
down in the water. They carry on to the eastern by mixing with bog myrtle (Myrica gale),
sedge (Carex sp.), joncus species and few reed mace in front of an open oak area
(Quercus sp.) with grass underwood (Deschampsia flexuosa). The northern part becomes a
reed swamp with reed mace, sedge (Carex sp.) and mosses. The western part is an islet of
grass swamp dominated by cottongrass (Eriophorum angustifolium).
The water is covered by Potamogeon natans.
Rishøj Sø : The south bank is bordered by willow which mixed in the western part with birch
before leading immediately to the coniferous forest. The north part is a reed swamp
dominated by reed mace. In the western, the coniferous forest turns in a scrubland meadow
with heather (Calluna vulgaris and Erica tetralix) and common crowberry
(Empetrum nigrum). It gets more various with sedges (Carex paniculata), joncus species ,
purple moor-grass (Molinia caerulea), cottongrass (Eriophorum angustifolium) when going
down. Finally, the vegetation stretches out over moss carpets covered by sedges
(Carex paniculata, C. rostrata), purple moor-grass (Molinia caerulea), cottongrass
(Eriophorum angustifolium) and bog-myrtle and turn in island and penninsula which go
meanderings in the western and north-western part of the lake. In the water, bulrushes
(Scripus lacustris) form some patch while Potamogeton natans land on the water surface.
Ællebæk Sø : the biggest lake is largely covered by common reed (Phragmite australis) with
few reed maces (Typha latifolia), a patch of horsetail and an islet of bulrushes
(Scripus lacustris). Potamogeton natans, Hydrochrius morus-ranae, Urticularia australis and
Sparganium sp. made up the aquatic vegetation.
From the western to the south-eastern, a coniferous forest (Pinus sp., Larix sp.) borders the
common area encolsed birch (Betula pubescens) and willow .
The rest of the bank lead to an open area of a mixture with bushes (Myrica gale, Salix sp.,
Vaccinium uliginosum), sedges (Carex paniculata, Carex echinata), joncus and cottongrass
(Eriophorum vaginatum, Eriophorum angustifolium) on thick moss carpet which turns on a
grass meadow (Deschampsia flexuosa, Molinia caerulea) with heather (Calluna vulgaris and
Erica tetralix) and common crowberry (Empetrum nigrum).
Waterflow breeding in Klosterheden State Forest, Denmark
24
In the water of the smallest lake, yellow pond-lily (Nymphaea lutea) shares the surface with
Potamogeton natans.
Tårnsøen : Bushes (Myrica gale, Salix sp.) spread over the bank of the biggest lake in an
arrengement of joncs, sedges (Carex sp), and grass (Molinia caerulea,
Deschampsia flexuosa). The most part of the bank lead to an open area of heather
(Calluna vulgaris) and common crowberry (Empetrum nigrum) which becomes a grass
meadow (Deschampsia flexuosa). The rest of the bank leads to a coniferous forest.
Only a few reed maces (Typha latifolia) are present, and especially in the northern part. The
aquatic vegetation is poor with small covers of Potamogeton natans. A small island on the
southern part is covered by trees.
The smallest lake is situated between two walls of coniferous forest. The moss bank encloses
bush cover (Myrica gale, Salix sp.) with horsetail (Equisetum sylvaticum). Reed maces and a
few common reeds (Phragmite australis) spread over on both sides. Burreeds
(Sparganium sp.), Potamogeon natans and marestail (Hippuris vulgaris) compose the aquatic
vegetation.
Stenbæk Sø : a scrubland meadow with heather (Calluna vulgaris) and common crowberry
(Empetrum nigrum) spread out over the north/north-eastern side and vary with moss areas
cover by bog asphodel (Narthecium ossifragum) and bog blueberry (Vaccinium uliginosum).
Close from the water, the vegetation is dominated by Eriophorum angustifolium growing up
on moss carpets with sedges and joncus species. Typha latifolia et Alisma plantago-aquatica
spread over on the bankside, the water and the island. The south part is composed of bushes
and a common reed.
2. Observations
The twelve areas were plotted in order to permit a monitoring with a 4-days interval for each
territory, therefore twice in 8 days. The study was carried out form May 5th to August 24th
2004.
The observation took place in the morning, on a sample road and/or high observation point
when possible. Binoculars (8x21) were used.
The water level was recorded as on a 3 steps scale (normal, high and low level). Weather
conditions were noted for rain, wind and fog.
The different broods were descriminated according to the growth of the young.
3. Graphical methodology
All data were analysed by graphical method (using Microsoft Excel® software).
In order to be able to compare the different areas, data were plotted by week (Fig.17 to 29).
When two observations from a same week, the higher number of birds seen per observation is
taken as equal to the number of birds for the week.
Waterflow breeding in Klosterheden State Forest, Denmark
25
C. Results
The breeding patterns have been summed up on Tab.6 & 7 and schemes 15 & 16.
The average number of kids by pair was calculated on the total number of kids on the total
number of broods (Tab.6).
1. Results by Species
1.1. Mallard (Anas Platyrhychos)
Recorded since March 29th, pair formation was observed during April especially in
Møllesøen. Thirteen breeding pair was estimated for KLS (Tab. 6).
The first young was observed in Møllesøen on May 6th with two broods (7 and 10 young
respectively). In the same week, one brood was observed at Ællebæk Sø (9 young). The next
week, 7 young were recorded in U1 (May 9th) and 6 in Fruerbæk (May 11th).
On June 3rd , in Møllesøen, a third brood was recorded with 7 kids, a forth (10 young) on
June 7th. On July, 2 new broods were recorded with 5 young each (Fig.14).
In Hestbæk, 3 young were recorded on June 3rd. On June 15th, a second brood (at least
6 young) was observed running away. However a young has been seen in Flynder Å in May.
In Flynder Å, 2 broods were observed, on June 23rd (7 young) and July 1st (4 young)
respectively.
During beavers observations, 6 juveniles were recorded in Ællebæk on June 20th and one
brood was also observed in the stream from Ællebæk on June 4th. Three grown-up young were
also recorded in July the 3rd on the Flynder Å.
On August 1st , a female with 5 young around 1-2 weeks were recorded in Risbæk.
Juvenile feathers was observed since June.
1.2. Muet swan (Cygnus olor)
A pair of swans was recorded regulary for the end of March in Møllesøen. A nest had been
built on the western bank but the swan was never seen hatching. Indeed absence of pair was
noted during May (10th & 27th) but they carry on to defend the area : a second pair was
recorded once but chased by the resident pair when it came back.
They have left Møllesøen after the 22nd week (Fig.17).
Another pair of swans ramdomly occuppied Tårnsøen during spring.
2 breeding pairs were estimated for KLS (Tab.6).
A swan was observed hatching since May 5th in Rishøj Sø and since May 14th in U2.
Rishøj Sø brood hached between May 17th and 21th (6 young : 5 grey, 1white). The same
brood with the pair was observed in Luskestien Sø in May 25th (Fig.22) and after in Stensbæk
Sø (no-monitored lake at first) since May 30th (Fig.28).
Since June 2nd, 2 children of the initial Rishøj Sø brood have disappeared. Another one was
observed floating on the lake on June 18th. On July 20th, an other young have disappeared.
Therefore, at the end, only 2 young were alive. This is the only brood which could be
monitored all the time.The swans have chosen the first island for a resting place.
U2 brood hached between June 2nd and 6th (4 young). After June 22nd, the family left the area
(Fig.24). The young were around 2-3 weeks-old.
Waterflow breeding in Klosterheden State Forest, Denmark
26
However, a family with 2 young around this age was observed in U1 on July the 3rd .
A pair with at least 3 young were also recorded in U1 (on the big dam) on the time of the
24th week.
An adult single swan was regulary observed in Ællebæk Sø from April to August (Fig.29).
1.3. Moorhen (Gallinula chloropus)
Adults were recorded on this study area since March 29th.
Five breeding pairs were estimated for KLS (Tab.6).
First young of moorhen are present in Risbæk since May 13th (4 young). Afterwards, they
have been observed until the end of May. Observation in this area in June and July are
sporadic (Fig. 22).
In Møllesøen, adults were regulary recorded since April and during the study (Fig.17).
On July the 4th, 2 young were recorded in Møllesøen but the brood may count 3 young
(obs. July 19th & 26th). Since July 29th, at least 2 young have got a juvenile feather.
In U2, records began in June on the lake as well as on the little dam. A brood is recorded on
July 20th with 2 young seen. However it may enclose 3 young (obs. July 24th).
Moorhen were regulary recorded in U1 with at least 3 individual present on the area.
On July 24th, a brood was observed (4 young).
Ællebæk Sø present a regular record pattern (Fig.29). No kids have been seen but a juvenile
have been well observed on August 7th.
The species have been noted in Tårnsøen (1 obs.), in Hestbæk (3 obs. in spring time),
Rishøj Sø (4 obs. in spring time) and Stenbæk Sø (Tab.7; Fig.16).
1.4. Pied wagtail (Motacilla alba)
Adults were observed in Klosterheden since April 2004. During the monitoring, this species
was regulary recorded only in Møllesøen, Flynder Å and U2 (Fig. 17, 18 & 24). However,
few observations were made in Ællebæk. Males were seen more often than females. Juveniles
were observed in Klosterheden in August.
1.5. Grey wagtail (Motacilla cinera)
This species was recorded regulary between the 21st and 25th week in Møllesøen and more
randomly during the rest of the study. Juvenile observation was made on June 7th in
Møllesøen.
Adults were also regulary seen in Flynder Å (Fig.18). They have bred in a nest under the
bridge in øvej (A.Hartelius, pers comm).
Waterflow breeding in Klosterheden State Forest, Denmark
27
1.6. Little grebe (Tachybaptus ruficollis)
The little grebe was recorded in Ællebæk Sø since April (Fig.29). One pair at least was
observed and males were recorded singing during April and May. One kid was observed with
an adult since August the 7th.
Presence of this species was confirmed also in Rørkær Sø (no-monitored) at the end of May
and beginning of June (A.Hartelius, pers. comm; Pers. obs.) and 2 young were observed since
June 9th. Another brood may have hatched afterwards as kids have been regulary seen until
August.
An adult was observed several time in Mølesøen, always diving inside the water vegetationcovered surface. Once it was heard singing.
Therefore, 2 breeding pairs were estimated for KLS (Tab. 6).
1.7. Grey heron (Ardea cinerea)
Grey herons were recorded in Fruerbæk, Rishøj Sø, Ællebæk Sø, U2 and Hestbæk.
Flyingindividuals are common and especially above U2.
During summer time, and after the juveniles have left the nest, observations were made also in
Flynder Å, Mollesøen, Tårnsøen. Great observations on juvenile were made in Ællebæk Sø.
Observations were also made on individual landing in the tree-peak close to Møllesøn and
Ællebæk Sø.
1.8. Cormorant(Phalacrocorax carbo)
Cormorants were often observed flying since April and were also recorded landing in
Møllesøen (April 12th & 14th , May 21st) and Tårnsøen (May 21st, June 4th).
1.9. Kingfisher (Alcedo atthis)
Kingfisher brood regularly in Flynder Å and in U2 (T. Borup Svendsen, A. Hartelius,
pers.comm.). Individuals werre recorded flying in Flynder Å and Møllesøen since May 6th but
the nest was built on Flynder Å near U2. An adult was also recorded in U2 landing on a
branch above the lake. In August, flying individuals were seen above Ællebæk and
Ællebæk Sø as well as a non-monitored part in U1.
1.10. Teal (Anas crecca)
Males were recorded on different lakes and dams during May. Females were only noted
always accompanied by their male : on Øvre Sø (May 5th), on Møllesøen (May 19th), in a
pond near Rishøjvej (May 21st) and Risbæk (on the stream).
1.11. Tufted duck (Aythya fuligula)
One pair of tufted ducks was chased away form Møllesøen by two mallard males on May 10th.
However, one pair plus one male were recoreded on May 19th. One pair was observed in
Rishøj Sø on May 17th.
Waterflow breeding in Klosterheden State Forest, Denmark
28
1.12. Coot (Fulica atra)
Presence of coots was only recorded in April in Møllesøen. However, one adult was recorded
in Stensbæk Sø on June 2nd.
1.13. Sandpiper
One individual was recorded in U1 on June 22th. Twice an individual was recorded in
Fruerbæk in August.
1.14. Egyptian goose (Alopochen aegyptiacus)
Two individuals of these geese were observed swimming in Tårnsøen in May 27th .
1.15. Water rail (Rallus aquaticus)
A water rail was heard singing in Hestbæk three times from May to June.
On August 23rd, an individual was recorded in Risbæk (A.Hartelius, pers. comm.).
1.16. Black stork (Ciconia nigra)
The Black stork was seen around KLS (T.B.Svendsen, pers. comm.). It is the 4th year that it is
recorded in the area.
1.17. Shelduck (Tadorna tadorna)
Two individuals were observed flying above Møllesøen in April 8th at sundown. They made
two passages.
1.18. Black headed Gull (Larus ridibundus) and other gull (Larus sp.)
This species have been seen near U2 wheeling round above the fisherie. No accurate record of
these species have been made as their presence is linking up only to the fisheries presence.
1.19. Unindentificated duck
Six ducks were seen in Ællebæk Sø at the last observation. They were half than a mallard
with a general spotted grey color. The observation was made by rain with dark light.
2. Results by territory
Species records for all the area is presented on from schemes 17 to 29.
Møllesøen present the best record of observed species (12 species) followed by U1
(7 species); Ællebæk Sø and U2 (6 species); Tårnsøen, Flynder Å, Risbæk area and Rishøj Sø
area (5 species), Ællebæk, Hestbæk and Stenbæk Sø (4 species), Fruerbæk (3 species) and
at last Øvre Sø (2 species) (Fig.16).
All the species are not recorded in all places which may coorespond with habitat and space
preferences.
Waterflow breeding in Klosterheden State Forest, Denmark
29
Apparently there seems to be no clear correlation between the size of the monitored area and
the number of brood inside (Tab.7; Fig.15).
D. Discussion
1. Records of the species
1.1. Mallard
Broods were discriminated on the young size. Confusion between the different broods could
happen.
The broods of May were seen on different areas far away from each other and without clear
water way between them. In Møllesøen, the two broods were seen in the same time with no
possibility for mistake. Therefore, five broods have hatched in early May (Møllesøen (2);
Ællebæk Sø (1); U1 (1); Fuerbæk (1)).
In June, the brood recorded in the stream linking up Ællebæk to Fynder Å on June 4th may
mix up with the brood seen on June 3rd. Mallard grown-ups as well as juveniles and broods
have been observed several times swimming along the Fynder Å and on the stream to
Ællebæk. As the dates of observation are too close, the brood must be the same seen twice.
The brood recorded in Ællebæk on June 20th was seen on sunset during beaver observation,
the size could be identified as a young (not juvenile). Five days discrimate this brood with the
brood seen in Hestbæk on June 15th (6 young). The brood seen in Flynder Å on June 23rd
(7 young) could be mixing up with the brood from Ællebæk. Broods in Møllesøen were
recorded with a four days interval. However, it is only with one week interval that the
difference in the young size are quite satisfactory to discrimate the brood. Therefore, in June a
maximum of six brood (Møllesøen (2); Fynder Å/Hestbæk/Ællebæk (4) were recorded and a
minimum of four brood (Møllesøen (1); Fynder Å/Hestbæk/Ællebæk (3)).
In July, two brood were seen in Møllesøen and on Flynder Å on the same day. As the
observations were made close to each other, the birds are considered to not move from one
area to an other, especially the young one. Therefore, three broods are recorded in July
(Møllesøen (2); Fynder Å (1)).
Mallard may not breed in the river Fynder Å. The width of the river is small with no secure
place to hatch. They may use it to move between Hestbæk, Ællebæk and Møllesøen, the
abundant vegetation protecting their move. A female with its young was seen getting under
cover above the bridge on Øvejen.
The young recorded in August in Risbæk count for a new brood as no young were recorded
previously in this area. The young were not able to fly at this time. They could walk from one
of the close lakes in the surroundings of Risbæk. However no brood have been seen there at
this time too. The brood is considered to have hatched a week before according to the size of
the young : around July 25th.
All the brood were seen accompanied by a female except in Fruerbæk which was
accompanied by a male. This observation in Fuerbæk is made against the litterature as the
female hatch alone the kids (Géroudet,1999).
Considering the whole brood, a total of 97 young have been observed (Tab.5). In August, the
juvenile get together especially in Møllesøen (44 juveniles on August 6th) and Ællebæk
(18 juveniles on August 23rd). However some of this juveniles could come from breeding
places outside KLS.
Waterflow breeding in Klosterheden State Forest, Denmark
30
Mallards have been recorded at least once in each area. In July and August, the juveniles were
dominant. They could mix up with the females as they share quite the same feather. Some of
the observation were made against the sunlight and juveniles were identified in doubt case.
1.2. Muet swan
Stenbæk Sø brood must be the Rishøj Sø brood. Five young were found as Stenbæk Sø,
having roughly the same age as the young in Rishøj Sø. The missed young could have died
during their walk from lake to lake as it happens frequently (predation by foxes). Stenbæk Sø
was not monitored at the beginning of the study. We can exclude the possibility that
Stenbæk Sø has got its own family of swans as there used to have breeding swans on this
place. We didn’t see a nest in this area but the nest in Rishøj Sø, U2 and Møllesøen have been
removed during the summer. In Møllesøen it was because of an increased water level.
Indeed the brood in Rishøj Sø have got a white young. This is dued to a mutation called
“false albinism” that followed the heredity rules. The broods in Stenbæk Sø count also a white
kid. Therefore, I assume that the broods in Stenbæk Sø come from Rishøj Sø.
A pair may have hatched in U1 on the big dam. At least three young were seen there in
June 10th. Therefore between four and two pairs have hatched this year in Klosterheden.
In Ællebæk Sø only one adult was recorded during the whole period of the study. However its
absence was also recorded. It has landed at the same place during a week but left the lake
after. Four days afterwards, it had returned. However, I have never seen a mate with him.
I think it didn’t form a pair and hatch. The reasons are not known.
1.3. Moorhen
Moorhen have usually two to three successive broods but I did not observe the second brood.
The broods have got a average of 3.5 young. This is lower than the litterature (5 – 11 eggs).
Predation on eggs could explain this low number.
It is easy to discriminate the different broods as the new-born are black but the juvenile
(called ”pullus”) have a brown olive color with a white throat (Heinzel & al., 1996;
Beaman & Madge, 1998).
Moorhen have been often recorded singing especially in U1. The singing record may
underestimate the population as only two singing heard in different places could be
discriminated.
1.4. Little grebe
Little grebes are a small waterfowl, diving all the time to find his food (insect, larva,
tadpole...). These two points made it difficult to observe. Furthermore, the little grebe found
in water plant cover surface some good camouflage. Its singing is characteristic and easily
recognizable.
Little grebe have two to three hatch per year (Géroudet, 1999). Adults hatch four to six eggs
during 21 days.
In Rørkær Sø, at least two kids were observed on June 9th but several brood may have hatched
as kids have been observed until August. As the lake was not monitored, the number of
broods and kids are not precisely known.
In Ællebæk Sø, only one young was recorded in August. This is much later than in
Rørkær Sø. Predation on eggs and kids could explain the low record of young. The vegatation
Waterflow breeding in Klosterheden State Forest, Denmark
31
is abundant in Ællebæk Sø with common reed and important cover of water plants and I may
have miss some individuals.
1.5. Grey heron
Grey heron breed in colony at the tree-peak. No such place have been recorded close to the
monitored area. Grey heron must breed near U2 as lots of individuals were often seen flying
and wheeling round above the forest (i.e. Klosterheden). This is supported by the spread of
the juveniles in Klosterheden since July (observation made on juveniles in Hestbæk,
Ællebæk Sø, Tårnsøen). Adults were identificated in doubt case. Therefore, there could have
more juveniles than seen.
A breeding place is known close to a beavers territory (A.Hartelius, pers comm).
1.6. Wagtail
Confusion between pied wagtail and grey wagtail is possible only with flying individuals.
However a confusion between female of grey wagtail and yellow wagtail (Motacilla flava) is
possible. Yellow wagtail was recorded in 2000 but not afterwards (Elmeros & al., 2004).
Grey wagtail have been identificated without mistake : the nuptial male have got a black
throat which makes it clearly different than a yellow wagtail (Heinzel & al., 1996). During the
record, I did not make a difference between male, female and juvenile as the observation time
was too short. However, grey wagtail juveniles have been identificated in June on some
observations and pied wagtail juveniles have been identificated on early August in Fruerhøj.
This last species may have bred earlier but the identification of juvenile was reliable only on
the observation in August.
1.7. Cormorant
This seabird could be found in lake, river, estuary and coastal water. They breed on cliffs,
rocks or trees (Heinzel & al., 1996). Seen more often flying, only three records were made on
landing bird. All of them were on big lake (Møllesøen 3,3 ha and Tårnsøen 1,3 ha).
The species did not breed in KLS on the monitored area but it may breed in the surrondings
closer to the sea.
1.8. Sandpiper
In U1, I observed a sandpiper feeding itself on the mud. It had got a white stomach, dark grey
wings, roughly neck side and face light grey, thin and quite long beak, long light legs (yellow
or green). After some minute, it flew to the peak on dead wood and stayed not moving for a
while. Afterwards, I identificated it as a common sandpiper (Actitis hypoleucos) or a green
sandpiper (Tringa ochropus) or a wood sandpiper (Tringa glareola). The habitat corresponds
better to the green sandpiper and the wood sandpiper. The observed individual did not move
the tail as it is written the common sandpiper do, but I well remembered a white sickle above
the wings. Therefore I don’t assess more precisely name to this sandpiper.
Common sandpiper have been observed in KLS and in very few number some wood
sandpiper (A.Hartelius, pers. comm.).
In Fuerbæk, I observed twice a sandpiper with four days intervalle.
The first fed itself on the mud and also find shelter in a bush. It walked in and out the
vegetation making the observation difficult. It had got a rather orange beak, a black band on
Waterflow breeding in Klosterheden State Forest, Denmark
32
the eye. The feather looked like the one of the common redshank but I was not able to see the
color of the legs. The stomach and the anus are white and keep moving.
The habitat is not the one of the common redshank and the observed individual is smaller than
the individual of this species. The behaviour corresponds to the one of the common sandpiper.
The second individual was seen against the sunlight, standing up on a grass mound before
jumping in the water and disappearing from view.
All the observations were made with bad conditions of light as they were in the shadow or
against the sunlight. Furthermore the glasses used were not efficient for this kind of
observation condition as they are not enough powerful.
1.9. Unindenticated duck
The ducks seen in Ællebæk on August 23rd were accompanied by mallard juveniles. Their size
was half of the mallard size. With the bad light conditions, nor the mirror color nor the beak
color could be determined. However a white area near the end of the tail has been clearly
seen. This could correspond to teal juveniles which feathers are close from the teal female.
2. Results by territory
Møllesøen present the best diversity (12 species) as well as the best record of breeding for
mallards (5-6 brood). This pattern could not be reliably linked to the beaver presence as it is
the biggest lake in KLS. However, the beavers don’t trouble the waterfowl breeding in this
place.
The typically beaver dam as Ællebæk, U1, Fruerbæk, Risbæk present an interesting waterfowl
breeding pattern with more or less one mallard brood each and two moorhen brood at the end.
Øvre Sø presents a bad record as well as the lack around Risbæk (Nedre Sø, Døjbæk Sø) due
to the presence of predator fish.
The bad record noted on the end of the monitoring at Risbæk may be linked to forest work
and noise disturbance in this area during august. The dams have also been drained quite
completely (waterlevel decreased of more than 50cm).
Tårnsøen is on a windy area and just few vegetation covered the water surface. This could
explain the low waterfowl presence.
Waterflow breeding in Klosterheden State Forest, Denmark
33
3. Beavers’influence.
With increasing the water area in Klosterheden, the beavers have favoured the presence of
waterfowl species (Moorhen, Sandpiper, Mallard, Wagtail) as well as wetland sparrow
species (Emberiza schoeniclus). The moorhen have profited on the beavers presence with four
broods in beavers territories (which two in beavers dams) against one in the control zone.
The mallards use all the water place created by the beavers as breeding place and resting
place. The swans have bred in a control zone and in a beaver territory and haven’t been
troubled by the beaver presence. The main factor seems to be the area rather than their
inhabitants. Swans breed in lake with abundant vegetation but have avoided Møllesøen and
Tårnsøen for undetermined reason. The breeding pattern this year is lower than it used to be :
swans have been breeding in Møllesøen, Tårnsøen, Risbæk sector, Stenbæk Sø and U2.
However no breeding season have been monitored until now and the breeding may have been
overestimated. Indeed, a pair of swans has been observed at the beginning of the breeding
season in all of this place but they didn’t choose to breed.
As they are territorial during the breeding period (Géroudet, 1999) the presence of one swan
in Ællebæk Sø prevent the coming of a breeding pair.
The sandpiper presence seems linked to the beaver activities as they have been observed only
in beaver dams who provide an adequate habitat.
Grey herons have profited of beavers area as eating and resting place whereas they could use
the forest for breeding.
Little grebes were not found yet in beaver dams but they are known to use all the place
suitable to breed, even the smallest piece of water (Géroudet, 1999). Therefore, the increase
of water place in KLS could favour this species on the long-term.
The swallow (Hirundo rustica) and house martin (Delichion urbica) have been observed all
over the forest but they use the water area to drink and catch their food (insects). Lots of
observations have been made above beaver territories. The diversity in insect population have
increased thanks to the beaver reintroduction (Elmeros & al., 2004) but the insect population
may have incresed as well by the increase of the wetland area. Therefore, swallows and house
martins find more food in the area and the population may increase. Furthermore, houses and
garages inside the forest provide lot of possible breeding places.
During springtime, teals and tufted ducks have been recorded using beaver territories and/or
control zones to rest. They breed in other parts of Juland. The possible juvenile of teal
observed in Ællebæk Sø on August 23rd could come from one of this places. Their presence is
promising and they could breed in KLS in a few years.
The black stork recorded since the beaver reintroduction would perhaps breed in a few
years here.
Globally this year was a poor year for bird observation (A.Hartelius, pers comm.) as it used
to. The study made should be considered to a starting point for evaluating the waterfowl
breeding in KLS. However the beavers presence have been favorable to the waterfowl species
by increasing the potentiality of resting and breeding places in the forest.
Waterflow breeding in Klosterheden State Forest, Denmark
34
E. Passerines observations
1. Ring-marking in Fruerbæk
Passerines species were recorded occassionnaly during this study. However, a ring-marking
study was carried out near Fruerbæk by an other authority (P.Flansmose for the museum of
Zoology).
Three field works were organized between May 2nd and May 31st.
Data of this study give a good knowledge of birds diversity in Klosterheden and near
beaver dams.
Catchings were more important near the stream where areas have been floated by beaver
activity than in the forest, even for forest specific species.
Recorded species
Acanthis cannabina (Linnet)
Acanthis flammea (Redpoll)
Anthus trivialis* (Tree pipit)
Carduelis spinus (Siskin)
Dendrocops major* (Lesser-spotted woodpecker)
Emberiza schoeniclus* (Common reed bunting)
Erithacus rubecula* (Robin)
Fringilla coelebs* (Chaffinch)
Garrulus glandarius (Jay)
Hirundo rustica* (Swallow)
Loxia curvirostra (Red crossbill)
Loxia pytyopsittacus (Parrot crossbill)
Parus ater* (Coal tit)
Parus cristatus* (Creasted tit)
Parus major* (Great tit)
Phylloscopus collybita* (Chiffchaff)
Phylloscopus trochilus* (Willow warbler)
Prunella modularis* (Dunnock)
Pyrruhula pyrruhula*
Regulus regulus* (Goldcrest)
Sylvia atricapilla* (Blackcap)
Sylvia communis* (common whitethroat)
Turdus merdula* (Blackbird)
2. Other observed species In Klosterheden
Most of this species was recorded during water bird monitoring or beaver observations.
However little ringed plovers (Charadrius dubius) and lapwings (Vanellus vanellus) were
recorded on private owners area in the limits of Klosterheden near the aerodrome. Lapwings
were also recorded in Stenbæk Sø on July. This two species have bred with young observed
since the end of May (A.Hartelius, pers, comm.).
Alauda arvensis* (Skylark)
Buteo Buteo (Common buzzard)
Carduelis chloris* (Green finch)
Waterflow breeding in Klosterheden State Forest, Denmark
35
Certhia familiaris (Common treecreeper) (A.Hartelius, pers.comm)
Charadrius dubius (Little ringed plover)
Coccothraustes coccothraustes (Hawfinch)
Columba palumbus* (Wood pigeon)
Corvus corax ( Raven)
Corvus corone cornix (Hooded crow)
Corvus monedula (Jackdaw)
Cuculus canorus (Cuckoo)
Delichion urbica (House martin)
Emberiza citrinella (Yellow bunting)
Falco sp. (Falcon)
Lanius collurio* (Red-backed shrike)
Miliaria calandra* (Corn bunting)
Parus caeruleus* (Blue tit)
Parus palustris* (Marsh tit)
Passer montanus (Tree sparrow)
Phasianus colchicus torquatus (phasian)
Pica pica (Magpie)
Picus viridis (Green woodpecker)
Streptopelia decaocto (Collared dove)
Strix aluco (Tawny owl)
Sturnus vulgaris* (Straling)
Sylvia borin* (Garden warbler)
Sylvia carruca* (Lesser whitethroat)
Troglodytes troglodytes* (Winter wren)
Turdus philomelos (Song thrush)
Turdus viscivorus (Mistle thrush)
Vanellus vanellus (Lapwings)
Young were observed and/or heard for the species in blue ink.
Species with a star were previously noted in the area (Elmeros & al., 2004). Three species
recorded in this report have not been seen : Muscicapa striata (Spotted flycatcher), Lullula
arborea (Woodlark), and Carduelis carduelis (Goldfinch). The last two species have not been
recorded since 2000 and their disappearance was assessed to natural variation in small
population (Elmeros & al., 2004).
In winter time, a Jack snipe (Lymnocryptes minimus) has been observed in Hestbæk
(T.B.Svendsen, pers.comm.). This species is in Danemark during winter only (Heinzel &
al., 1996).
Waterflow breeding in Klosterheden State Forest, Denmark
36
3. Other observations
Odonata:
In Klosterheden, from May to August :
- Pyrrhosoma nymphula
- Ischnura elegans (Blue-tailed damselfly)
- Coenagrion pulchellum (Variable damselfly)
- Calopteryx virgo (Beautiful demoiselle)
- Calopteryx splendens (Banded demoiselle)
- Libellula quadrimaculata ( Four-spotted skimmer)
- Brachytron pratense (Hairy dragonfly)
- Corduliidae sp
- Aeshnidae sp
- Libellulidae sp
Lepidoptera
In Klosterheden, from April to August :
- Anthocharis cardamines (IV-V) (Orange Tip)
- Inachis io (IV-Vand VIII) (Peacock)
- Euthrix potatoria (caterpillar of Drinker moth)
- Aphantopus hyperantus (VI-VII) (Ringlet)
- Heodes virgaureae (VII)
- Pieris sp.
Waterflow breeding in Klosterheden State Forest, Denmark
37
Acknowledgements
I would like to thank Sten Asbirk, Thomas Borup Svendsen, Ole Olsen for supervision and
advices, Karstern Jensen and Arne Hartelius for assistance in the field, Jérôme Lhullier for
correcting the manuscript. I would like to thank Peder Flensmose and Henry Thørgersen for
inviting me to their ring-marking. I also thanks all the Klosterheden’s staff for help and
precious informations.
38
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40
Fig.1. Tree and branches cut by beavers (Flynder Å, 2004)
41
Fig.2. Beaver territories in Klosterheden Forest District and surroundings in 2003 (Elmeros & al., 2004). The empty circles show
the release sites and the black circles the known lodges. I1 : Møllesøen, I2 : Hestbæk, I3 : Flynder Å, I4 : Risbæk, I5 :
Fruerbæk.
42
Møllesøen
Flynder Å
Ællebæk
Hestbæk
Fig.3. Beaver activity area in Møllesøen and Hestbæk beaver territories.
43
Fig.4. Map of the beaver scent-mark.
44
Møllesøen
Fynder Å
Hestbæk
Fig.5. Beaver territories according to the study results.
45
Tab.1. Beaver observation characteristics during the beaver count from October 2000 to April 2004
Beaver count
10.11.12 Oct 2000
24.25.26 Ap 2001
1.2.3 Oct 2001
16.17.18 Ap 2002
9.10.11 Oct 2002
9.10.11 Ap 2003
28.29.30 Sept 2003
29.30 Ap & 1 May 2004
Adults
31
24
18
35
16
44
23
38
Evening
Juveniles
0,5
7
0
9
10
18
14
6
Watches
20
49
42
56
39
66
53
60
Adultes
35
29
33
37
23
38
18
36
Morning
Juveniles
0,5
3
3
4
3
9
7
8
Watches
20
54
43
50
38
64
53
60
46
Beavers seen on evening
Average of observations/watches
0,9
0,8
0,7
0,6
Beavers seen on morning
Adults seen on evening
Adults seen on morning
Juveniles seen on evening
Juveniles seen on morning
0,5
0,4
0,3
0,2
0,1
0,0
Fig.6. Distribution of the beaver observations according to the age of the observed beaver during beaver counts from 2000 to
2004
47
2,0
1,8
observations/watches
1,6
1,4
1,2
1,0
0,8
0,6
0,4
0,2
0,0
oct. 2000
april 2001
oct 2001
april 2002
oct 2002
april 2003
oct 2003
Beavers Counting
ap. & may
2004
Beavers seen on evening
Beavers seen on morning
Adults seen on evening
Adults seen on morning
Juveniles seen on evening
Juveniles seen on morning
Fig.7.Variation of beaver observations according to the age of the observed beaver during beaver counts from 2000 to 2004
48
Tab.2. Hours of the beaver observation according to avaible data from beaver counts from 2001 to 2004
Beaver Counts
24.25.26 Ap 2001
1.2.3 Oct 2001
16.17.18 Ap 2002
9.10.11 Oct 2002
9.10.11 Ap 2003
28.29.30 Sept 2003
29.30 Ap & 1 May 2004
Before sunset
13
5
15
4
26
4
21
After sunset
15
12
31
23
38
32
24
Before sunrise
16
22
14
18
26
21
27
After sunrise
19
13
17
6
15
8
16
49
observations / watches made on evening
1,00
0,90
0,80
0,70
0,60
0,50
0,40
0,30
0,20
0,10
0,00
ap. 2001
oct. 2001
ap. 2002
oct. 2002
ap. 2003
oct. 2003
ap. 2004
Beaver count
obs. before sunset
obs.after sunset
Fig.8. Distribution of the beaver observations made on evening during beaver counts.
50
observations / watches made on morning
1,00
0,90
0,80
0,70
0,60
0,50
0,40
0,30
0,20
0,10
0,00
ap. 2001
oct. 2001
ap. 2002
oct. 2002
ap. 2003
oct. 2003
ap. 2004
Beaver count
obs. before sunrise
obs. after sunrise
Fig.9. Distribution of beaver observations made on morning during beaver counts.
51
Tab.3. Beaver population estimation obtained with different methods of counting according to data of the beaver counts from
April 2000 to April 2004
Method
2 days / 2 1
day/
counting
counting
1 days/ October 2 days / April 1 day / April
counting
counting
counting
Population in 1999
Population in 2004
(without taking out the
dead beaver)
Information conserved
Information lost
Minimal
18 beavers
54 beavers
2 2
days/
October
counting
18 beavers
18 beavers
47,5 ± 0,7 40 beavers
beavers
18 beavers
18 beavers
37,67 ± 1,15 47 beavers
beavers
18 beavers
42,5 ± 1,29
beavers
87,96 %
12,04 %
43 beavers in
1,6 % of case
52 beavers in
1,6 % of case
45,5 ± 0,7
beavers
87,5 %
12,5 %
29,5 ± 0,7
beavers
81,94 %
18,06 %
69,75 %
30,67 %
37 beavers in
50 % of case
39 beavers in
16,67 % of case
35,67 ± 1,15
beavers
68,60 %
31,40 %
19,67 ± 1,15
beavers
54,64 %
45,36 %
78,70 %
21,30 %
41 beavers in
25 % of case
44 beavers in
25 % of case
40,5 ± 1,29
beavers
77,88 %
22,12 %
24,5 ± 1,29
beavers
68,06 %
31,94 %
100 %
0%
Maximal
Population in 2004
52 beavers
Information conserved
Information lost
Population growth
100 %
0%
36 beavers
Information conserved
Information lost
100 %
0%
74,07 %
25,93 %
38 beavers
73,08 %
26,92 %
22 beavers
61,11 %
38,89 %
87,04 %
12,96 %
45 beavers
86,54 %
13,46 %
29 beavers
80,56 %
19,44 %
52
50
45
Information lost (%)
40
35
30
25
20
15
10
5
0
2days/ 2 countings
1 day/ 2 count
2 day/ October
count
Population growth
1 day/ October
count
2 day/ April count
1 day/ April count
Population estimation without taking out the dead beavers
Population estimation (with taking out the dead beavers)
Fig.10. Variation of the loss of information according to the considered information.
53
100%
90%
Sight of juveniles
80%
70%
60%
50%
40%
30%
20%
10%
0%
ap. 2001 oct. 2001 ap. 2002 oct. 2002 ap. 2003 oct. 2003 ap. 2004
total
Beavers count
juvenile seen once
juvenile seen twice
juvenile seen three times
juveniles seen four times
Fig.11. Sight of juveniles during the beaver count from April 2OO1 to April 2004
54
Tab.4. Breeding in beaver territoies from 2000 to 2003
Territories
Kids born in 2000
Kids born in 2001
Kids born in 2002
Møllesøen
Hestbæk
Risbæk
Kurts Dam (U2)
Bækmarksbro (U4)
Keldseng (U1)
Fruerbæk
Høkær (U8)
U6
U3
U5
Grønkær bæk (U7)
1
1
2
1
1
2
1
1
3
1
1
2
1
0
3
2
Kids Total
1
Kids born in 2003
3
1
1
1
1
2
1
1
1
6
10
11
9
Population
24
34
45
52
fecond rate (‰)
0,25
0,29
0,24
0,17
55
12
10
8
6
4
2
0
1999
2000
2001
2002
2003
years
beaver kids
Fig.12. Beaver breeding in Danmark since the reintroduction of 18 individuals on October 1999. The kids for 1999 are
reintroducted kids
56
Tab.5. Areas monitored for waterfowl breeding
Study area
Møllesøen
Fynder Å
Ællebæk
Hestbæk
Fruerbæk
Risbæk
U1
U2
Øvre Sø
Rishøj Sø
Ællebæk Sø
Tårnsøen
Stenbæk Sø
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
Surface
ca.3,3 ha.
Habitat
lake
stream
pond
pond
pond
stream/pond
pond
lake/pond
lake
lake
lake
lake
lake
0,2 ha. floded
1 ha. floded
0,2 ha. folded
1 ha. floded
2 ha. floded
ca. 1,1 ha.
ca. 1,4 ha
ca. 1,3 ha
ca. 0,7 ha
Beavers presence
present
present
present
present
present
present
present
present
absent
absent
absent
absent
absent
1
10
2
11
3
4
9
12
6
13
7
8
5
57
Fig.13. Areas monitored for waterfowl breeding
45
7/06
25
20
1/7
Individuals
30
6/05
35
3/06
40
J
Y
F
15
9/7
10
M
5
0
Fig.14. Mallard presence and observation of the brood in Møllesøen from May 2004 to August 2004
58
Tab.6. Breeding pattern in KLS during the summer of 2004
Breeding pair
Mallard
Muet swan
Moorhen
Little grebe
13
2
5
2
Average
of
young by pair
7,2
5
3
1.5
59
Tab.7. Number of observations made on waterfowl in Klosterheden State Forest between April and August 2004.
The dates are the first and the last observation for the species in the given area. Observations made on juveniles are written in
bold. The date of each brood correspond to the date of the first young observation, they are written in bold with the number of
young in bracket. Abreviation: A=April ; M=May ; J=June ; j=July ; a=August
Ardea Cinera
Møllesøen
A=8; M=7;
j=8; A=6
19/6-18/8
J=7; J=2, j=1; A=1
Cygnus Olor
Anas platyrhychos
19/6-22/8
J=1 ; j=2; A=2
29/3-30/5
A=8 ; M=5
29/3-22/8
A=9; M=7+7, J=7+5,
j=3+6; A=1+6
6/5(7); 6/5(10); 3/6(7);
7/6(10); 1/7(5); 9/7(5)
17/4 –13/7
A=4 ;M=2 ;
J=2+1;
j=1+3
23/6(7); 1/7(4)
9/4-4/7
A=1 ; M=1 ; J=3+1;
j=1+1
4/6 (x); 20/6 (6)
10/5-29/7
M=3; J=2+2; j=1
3/6(3); 15/6(6)
11/5-11/8
M=4+1; J=0; j=1; A=1
11/5(6)
2/6-1/8
J=1+1, j=1; A=1+1
25/7 (5)
8/4 : A=1
9/7: j=1
Fynder Å
A=6; M=7;
j=8; A=6
Tachybaptus
ruficollis
J=7;
Ællebæk
A=1; M=7;
j=8; A=6
J=7;
Hestbæk
7/7-22/8
J=7; J=1 ; j=2+1; A=1
A=1; M=7;
j=8; A=6
Fruerbæk
A=1; M=7;
j=8; A=6
7/5-22/7
J=7; M=2 ; J=2 ; j=1
8/7: j=1
Risbæk
A=1; M=7;
j=8; A=6
J=7;
Nedre Sø
A=1; M=7;
j=8; A=6
8/7 : j=1
M=7; J=7; j=8; A=6
25/5 : M=1
5/8: A=1
J=7;
4/7: j=1+1
U1
M=7; J=7; j=8; A=6
A=1; M=7;
j=8; A=6
17/4-8/7: M=1; J=1;
J=7; j=2
individual were often
seen flying
Øvre Sø
A=1; M=7;
j=8; A=6
J=7;
9/5: M=1
6/5-18/6
M=6; J=1;
5/5-18/6
M=5+3; J=4
13/5(4)
J=7;
25/5-8/7
M=1; J=1; j=1
5/5-28/7
M=6+2; J=3+2; j=6
9/5(7)
5/5-21/8
M=7; J=7; j=6+1;
A=3+1
28/7(4)
17/4-8/7
17/4-22/8
6/6-21/8
A=1; M=6; J= 6+5; A=1; M=3; J=2; j=0; J=5; j=3+3 ; A=3+1
j=1
A=2
20/7(3)
6/6 (4)
13/5-14/6
M=2; J=1+1
5/5-21/5
5/5-2/6
M=5+1
M=4; J=1
21/5 (6)
19/5-19/8: M=3; J=1; 3/4-7/8
12/4-23/8
3/4-23/8
Ællebæk Sø
A=5; M=5; J=2 ; j=5; A=1; M=5; J=5; j=7; A=4; M=3+4;
A=5; M=7; J=7; j=2+2; A=1
A=4+3
A=4
j=2+3, A=4
j=8; A=6
7/8(1)?
7/4(9)
20/6-13/8: J=1; j=1+1;
19/5-31/5
6/5-27/5
Tårnsøen
M=4
M=4;
M=8; J=7; j=8; A=6 A=1
18/6: J=1
30/5-1/9
10/6-13/8
Stensbæk Sø
M=1+1;
J=7+7; J=1; j=2; A=1
J=8+8; A=5+5
9/6(2)
Rørkæk Sø
Rishøj Sø
A=1; M=7;
j=8; A=6
J=4;
25/5
M=1+1;
Dojbæk Sø
U2
29/3-22/8
A=6;
M=7;
j=6+5; A=3+4
4/7(3)
J=7;
Luskestein Sø
A=1; M=7;
j=8; A=6
Gallinula
chloropus
13/5-14/6
M=2; J=3
11/5-7/8
J=1+3; M=6; J=4; j=4+1; A=1
18/7(1)
6/5 : M=1
60
Moorhen
Mallard
Swan
Little grebe
Fig.15. Waterfowl broods according to the monitoring made in KLS during the summer of 2004
61
Moorhen
Pied wagtail
Teal
Mallard
grey wagtail
Tufted duck
Muet swan
Cormorant
Coot
Little grebe
Sandpiper
Egyptian goose
Grey heron
Kingfisher
Water rail
Fig.16. Waterfowl species observed in KLS according to the monitored area during the summer of 2004.
62
22
23
24
25
26
27
28
29
30
31
32
33
W eeks
Juvenile Swan
M ale M allard
Fem ale M allard
Juvenile M allard
Adult M oorhen
Pied wagtail
G rey wagtail
Little grebe
G rey heron
Corm orant
Tufted duck
Sand piper
King fisher
Egyptian gouse
W ater rail
Fig.17. Waterfowl records in Møllesøen from May to August 2004
34
12
10
8
6
4
2
0
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
30
31
32
33
Weeks
Fig.18. Waterfowl records on Flynder Å from May to August 2004. (For the legend, see Fig. 17)
10
9
8
7
6
5
4
3
2
1
0
19
20
21
22
23
24
25
26
27
28
29
Weeks
Fig.19. Waterfowl records on Hestbæk from May to August 2004. (For the legend, see Fig. 17)
65
34
4,5
4
3,5
3
2,5
2
1,5
1
0,5
0
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
33
34
34
Weeks
Fig.20. Waterfowl records on Ællebæk from May to August 2004. (For the legend, see Fig.17)
12
10
8
6
4
2
0
19
20
21
22
23
24
25
26
27
28
29
30
31
32
Weeks
Fig.21. Waterfowl records on Fruerbæk from May to August 2004. (For the legend, see Fig. 17)
66
18
16
14
12
10
8
6
4
2
0
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
Weeks
Fig.22. Waterfowl records on Risbæk from May to August 2004. (For the legend, see Fig. 17)
18
16
14
12
10
8
6
4
2
0
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
Weeks
Fig.23. Waterfowl records on U1 from May to August 2004. (For the legend, see Fig. 17)
67
34
14
12
10
8
6
4
2
0
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
Weeks
Fig.24. Waterfowl records on U2 from May to August 2004. (For the legend, see Fig. 17)
12
10
8
6
4
2
0
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
Weeks
Fig.25. Waterfowl records on Rishøj Sø from May to August 2004. (For the legend, see Fig. 17)
68
9
8
7
6
5
4
3
2
1
0
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
Weeks
Fig.26. Waterfowl records on Øvre Sø from May to August 2004. (For the legend, see Fig. 17)
7
6
5
4
3
2
1
0
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
Weeks
Fig.27. Waterfowl records on Tårnsøen from May to August 2004. (For the legend, see Fig. 17)
69
14
12
10
8
6
4
2
0
22
23
24
25
26
27
28
29
30
31
32
33
34
Weeks
Adult Swan
Juvenile Swan
Male Mallard
Female Mallard
Juvenile Mallard
Adult Moorhen
Coot
Lapwing
Fig.28. Waterfowl records on Stenbæk Sø from May to August 2004.
70
22
23
24
25
26
Weeks
27
28
29
30
31
Fig.29. Waterfowl records on Ællebæk Sø from May to August 2004. (For the legend, see Fig. 17)
32
33
34
Bibliography