African Journal of Marine Science 2007, 29(1): 105–111
Printed in South Africa — All rights reserved
Copyright © NISC Pty Ltd
AFRICAN JOURNAL OF
MARINE SCIENCE
ISSN 1874–232X
doi: 10.2989/AJMS.2007.29.1.9.74
Management of avian cholera Pasteurella multocida outbreaks on Dyer
Island, South Africa, 2002–2005
LJ Waller1,2* and LG Underhill2
1
CapeNature, 16 Seventeenth Avenue, Voëlklip, Hermanus 7200, South Africa
Avian Demography Unit, Department of Statistical Sciences, University of CapeTown, Rondebosch 7701, South Africa
* Corresponding author, email: [email protected]
2
In 2002 there was a widespread epizootic involving
seabirds on five of the offshore islands of the Western
Cape, South Africa. Since then, avian cholera Pasteurella multocida outbreaks have been occurring annually
on one of these islands, Dyer Island. This paper reports
on the three subsequent summers, 2003/04, 2004/05 and
2005/06, during which further avian cholera outbreaks
were recorded. It focuses on the outbreak in 2004/05,
which was the largest in extent and the most closely
monitored. The mortalities during 2005/06 were not as
extensive as expected. The management measures
used to bring these outbreaks under control are described. Removal of all the carcasses from the entire island
in one day is important in reducing mortality. Management intervention is required to reduce the negative
impacts of disturbance due to kelp gull Lasus dominicanus predation on other breeding seabirds, primarily
the African penguin Spheniscus demersus, during the
carcass collection process.
Keywords: avian cholera, Cape cormorant, disturbance, Dyer Island, epizootic, Pasteurella multocida, Phalacrocorax capensis, wildlife disease
Introduction
Globally, the frequency of avian cholera Pasteurella multocida outbreaks is increasing; it has become the most important infectious wildlife disease of waterbirds in the US,
resulting in more bird deaths than any other avian disease
(Friend 1999). The extent of mortalities in a single outbreak
can sometimes reach in excess of 70 000 birds, such as
occurred in Californian waterfowl during 1965–1966 (Rosen
1972) and 30 000 lesser snow geese Chen c. caerulescens
on Banks Island, Canada, in 1995 (Samuel et al. 1999).
Events such as these are referred to as epizootics, which is a
disease affecting a greater number of animals than normal
and typically occurrences involving many animals in the same
region at the same time (Friend 1999). Botzler (1991) reported that epizootics of avian cholera among wild birds other
than waterfowl (Anseriformes, ducks, swans and geese) are
uncommon. For example, avian cholera has been reported
from brown skuas Catharacta antarctica in Antarctica and
from rockhopper penguins Eudyptes chrysocome in New
Zealand (Parmelee et al. 1979, de Lisle et al. 1990).
A review of avian cholera in South Africa established that
the first outbreak of the disease was in the early 1940s at
Malgas Island in Cape gannets Morus capensis (AJ
Williams and VL Ward, CapeNature, unpublished data).
Since then, six outbreaks in this region have been reported,
involving nine species of seabirds, with the Cape cormorant
Phalacrocorax capensis experiencing the greatest mortality.
In 1991, large-scale mortality of Cape cormorants was
recorded at eight islands off the coast of the Western Cape
Province (Crawford et al. 1992). The largest mortalities
were recorded at Dassen and Dyer islands. In 2002, there
was a widespread epizootic involving seabirds in this region
(Williams and Ward 2002). Seabird populations on Bird
Island (Lambert’s Bay) and Dyer Island were the most
severely effected, with more than 7 000 Cape cormorant
mortalities recorded at these two localities. To date, Dyer
Island is the only locality to have reported further large
numbers of mortality in subsequent outbreaks of avian
cholera in South African seabirds.
Overall, in avian cholera outbreaks in the Western Cape,
the largest mortality has been of Cape cormorants. This
species is endemic to southern Africa, breeding between
northern Namibia and the Eastern Cape Province (Crawford et al. 1992). They are colonial breeders, breeding
predominantly on offshore islands, and population sizes are
monitored regularly (Hockey et al. 2005).
This paper reports on the first recorded outbreak of avian
cholera at Dyer Island since 1991. These occurred in 2002
and in the three subsequent summers, 2003/04, 2004/05
and 2005/06. It focuses on the outbreak in 2004/05, which
caused the greatest mortality. The summers of 2004/05 and
2005/06 were more closely monitored than those in the
summers of 2002 and 2003/04. The paper describes the
management measures used to bring these outbreaks
under control.
106
Material and Methods
Study site
Dyer Island (34°41’S, 19°25’E) was designated an Important Bird Area (Barnes 1998), one of 101 such areas in
South Africa, and 1 228 in Africa (Fishpool and Evans
2001). It is a small (20ha) island off the south-western coast
of South Africa, and a provincial nature reserve, managed
by CapeNature. Dyer Island lies 55km west of Cape
Agulhas. The interior of the island is flat (the highest height
is c. 6m above sea level) and has a surface of pebble and
sand. The vegetation consists mostly of low shrubs, including the indigenous herb Mesembryanthemum aitonis, which
is most abundant, and exotic weeds, of which Lavatera
arborea is the most abundant. In areas in which seabird
colonies form, fresh guano kills the vegetation. In areas
where seabirds have not bred for several years, there is
lush vegetation for several months during spring and early
summer, after the winter rains (Barnes 1998).
Dyer Island supports three threatened bird species: bank
cormorant Phalacrocorax neglectus (Endangered), African
penguin Spheniscus demersus (Vulnerable) and the roseate
tern Sterna dougallii (Critically Endangered Regionally)
(Barnes 1998, du Toit et al. 2003). In the 1970s, this island
supported the world’s largest colony of African penguins,
about 25 000 pairs; by 2005, the population had decreased to 3 500 pairs, making Dyer Island the sixthlargest colony (Crawford et al. 1995, Underhill et al. 2006).
A range of other seabird species breeds on the island:
white-breasted cormorants Phalacrocorax lucidus, Cape
cormorants P. capensis, crowned cormorants P. coronatus,
kelp gulls Larus dominicanus, Hartlaub’s gulls L. hartlaubii
and swift terns Sterna bergii (Barnes 1998). It supports
substantial numbers of migrant waders, including more
than 1% of the world’s African black oystercatcher Haematopus moquini population (Venter et al. 2002, Wortel et al.
2003).
Waller and Underhill
conducted on the liver, spleen and kidney to diagnose avian
cholera. The field rangers used gloves when handling the
carcasses. The carcasses were picked up by the beak to
avoid further possible contamination of the soil by fluid leaking out of the nasal passages and were placed in a plastic
bag. If the whole carcass could not be sent off the island
immediately (which was often the case due to sea conditions), it was frozen and sent off as soon as possible.
If it became clear that an epizootic was occurring, the
number of field rangers and labourers on the island was
increased as rapidly as resources permitted. In addition, a
supply of firewood was brought to the island to fuel the
incinerator. Lime was also brought, and used to cover
carcasses in the incinerator area that had not been burnt at
the end of each day.
The island is divided into six management zones. To
reduce disturbance levels to the breeding seabirds on the
island (predominantly Cape cormorants and African penguins), a maximum of two field rangers were assigned to
remove carcasses in each zone at one time. Human disturbance caused nest desertion and immediate egg and/or
chick predation by kelp gulls.
Six staff collected carcasses and placed them in industrial strength black bags (or doubled up the bags when
normal refuse bags were used, to prevent splitting). The
mass of an adult bird is approximately 1.2kg, and an average of 15 carcasses was collected per bag (18kg), after
which the bags tended to split. The bags were carried to the
incinerator. Birds were counted per bag, and daily totals
recorded; in 2004/05 and 2005/06, the numbers of birds per
management zone were recorded daily.
Two staff members were deployed to incinerate the
carcasses (Figure 1). The steel incinerator was 3m high,
with a capacity to burn c. 400 carcasses per day. A wood
fire was built at the bottom of the incinerator; the carcasses
were placed into the incinerator through a door on the side,
onto a grid located about 1m above the fire. Usually, 5–6
birds were introduced into the incinerator at one time. Wood
Fieldwork protocols
Avian cholera is a contagious disease (Friend 1999), and
regular monitoring for bird mortality is important to identify an
epizootic as early as possible, providing the greatest opportunity to minimise high losses (Botzler 1991). Field signs of
avian cholera include daily high mortality of birds that appear
to be in good condition. The island management protocols
therefore required that the level of vigilance be increased
once fresh (Cape cormorant in particular) carcasses are
discovered. Patrols were conducted daily around the island
(CapeNature, unpublished data). From October onwards,
field rangers were instructed to maintain a close watch for
Cape cormorant carcasses. Once detected, the carcass was
recorded as either a mortality as a result of predation (obvious seal bite marks) or unknown. The date and location on
the island (by management zone) was also recorded. If a
whole fresh carcass was found with no evidence of bite
marks, the onset of avian cholera was suspected and the
carcass was sent to the State Veterinary Services,
Stellenbosch, where bacterial culture and isolations were
Figure 1: Incinerator on Dyer Island, Western Cape, South Africa,
used to burn bird carcasses, with black bags of dead birds in the
foreground
African Journal of Marine Science 2007, 29(1): 105–111
107
was continuously added to maintain the heat, and the grids
manually shifted to allow the bones to fall through to the
ground to prevent the buildup of bones on the grid which
would reduce the effectiveness of the fire. At the end of
each day, those carcasses that were not burnt were
covered with powdered lime. This was to dry the carcasses
out and prevent them from decomposing to such an extent
that they became difficult to burn.
The primary objective was to reach the position when the
entire island could be swept clear of all dead birds once
daily. Once this stage was reached, daily searches for dead
cormorants continued until the mortality rate reached
normal levels, and the epizootic was considered to have
finished. A normal mortality level for Cape cormorants after
the occurrence of the outbreak was considered to be less
than an average daily death rate of five adults or fleged
juveniles. Once the mortality had reached less than 50 per
day for three consecutive days, the additional staff
deployed to the island were withdrawn, and the field
rangers continued to maintain their daily patrols, collecting
and incinerating carcasses.
Results
Significance of Dyer Island to breeding Cape cormorants
The overall trend in the population of Cape cormorants in
the Western Cape appear to be decreasing (Table 1). Since
1993, the percentage of this population which bred annually
Table 1: Numbers of pairs of Cape cormorants breeding on Dyer
Island and the total at six islands of the Western Cape (Bird
Island -Lambert’s Bay, Malgas, Jutten, Vondeling, Dassen, Dyer)
(RJM Crawford, MCM, unpublished data)
Year
Dyer Island
Total
Dyer Island population as
percentage of total
1956*
1978
1985
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
3 186
35 580
48 293
23 335
3 255
8 601
32 964
18 419
18 350
14 556
14 768
13 828
11 043
17 936
15 617
18 105
18 436
9 207
15 700
33 024
22 766
96 527
103 741
62 404
95 735
8 441
59 977
90 296
72 642
35 618
25 545
35 125
26 715
24 916
22 185
33 938
25 727
40 081
14 507
27 942
46 161
35 307
3
34
77
24
39
14
37
25
52
57
42
52
44
81
46
70
46
63
56
72
64
* 1956 refers to the 1956/57 breeding season
at Dyer Island lay between 43% and 92%, a larger population than at any other colony (Table 1). In the Western
Cape, Cape cormorants breed throughout the year, peaking
between September and February but sometimes as late
as May, and is related to food availability (Crawford and
Dyer 1995, Crawford et al. 1999). Peak breeding on the
island is usually from October to February, but sometimes
continues into April (LJW pers. obs).
Epizootics impacting Cape cormorants and other
species on Dyer Island
Avian cholera is a highly contagious disease, and often
within the following few days after the first carcass was
detected, the island was littered with Cape cormorant
carcasses, and the laboratory reports confirmed what was
seen in the field. Few sick birds were seen because of the
acute nature of the disease (Friend 1999), and those that
were appeared to be very lethargic and were able to be
approached at close proximity. Adult Cape cormorants often
died on their nests, and in less than 12 hours after an area
had been cleared of carcasses, more carcasses were
discovered on the island.
Outbreaks of avian cholera on Dyer Island occurred in four
consecutive years since 2002, with the 2004/05 outbreak
producing the largest adult mortality. During the first outbreak
in 2002 more than 7 000 adult Cape cormorants died. The
second outbreak occurred between October 2003 and
January 2004 when 1 750 adult, and 5 355 juvenile Cape
cormorants died. The third outbreak occurred from October
2004 to January 2005, when 9 733 adults and 4 794 juvenile
Cape cormorants died. A count of breeding Cape cormorants
in October 2004 was conducted less than a week before
the outbreak occurred, and a total of 33 024 breeding pairs
was obtained (Marine and Coastal Management [MCM],
unpublished data). The mortality of 9 500 adults represented 14% of the population. During 2005/06, 1 118 mortalities were recorded, 352 adults and 763 juveniles.
Mortality of other species was recorded during 2004/05,
but it involved small numbers of birds. This included one
African penguin, one African black oystercatcher and three
white-breasted cormorants. None of these birds was sent to
the laboratory for testing.
The pattern of numbers of daily carcasses collected
showed a sharp decrease once all carcasses were collected in a single day (Figure 2). Details of daily counts are
listed in the Appendix. The figures highlighted in bold indicate the first day that the entire island was cleared of
carcasses during 2003/04 and 2004/05. In both occasions,
numbers of carcasses collected daily dropped subsequently. During 2004/05, the first day that the island was
cleared entirely of adult carcasses was 7 October when
2 252 birds were collected. After 7 October, the number of
carcasses collected decreased every day, and every day
thereafter all carcasses were removed from the island.
Figure 2a shows the rapid decrease of new juvenile
carcasses collected after the island had been cleared for
the first time on 30 December 2003. A similar pattern is
seen in Figure 2b, where the number of fresh adult
carcasses decreased after the island was cleared for the
108
Waller and Underhill
700
600
(a)
Juveniles in 2003/04
500
400
300
200
100
28
Dec
(b)
31
Jan
03
06
09
12
15
18
21
24
27
30
02
05
Feb
Adults in 2004/05
2 000
1500
1000
500
02
NUMBER OF BIRDS
Oct
(c)
05
08
11
14
17
20
23
26
29
01
04
Nov
07
10
13
Juveniles in 2004/05
400
300
200
100
11
30
Nov
(d)
14
17
20
23
26
29
02
Dec
05
08
11
14
17
20
23
26
29
Adults in 2005/06
25
20
15
10
5
15
120
Oct
(e)
19
23
29
4
8
12
16
19
22
26
15
18
22
03
Mar
Juveniles in 2005/06
100
80
60
40
20
29
Oct
7
14
17
22
26
29
DATE
03
Jan
06
10
03
22
Figure 2: Daily totals of Cape cormorant carcasses collected during avian cholera outbreaks at Dyer Island, Western Cape, South Africa
06
African Journal of Marine Science 2007, 29(1): 105–111
first time on 7 October 2004. The mortality of juveniles
during 2004/05 and of adults and juveniles in 2005/06 did
not follow the same pattern (Figure 2c–e). Mortality was
spread over a greater time period, even though the entire
island was cleared every day.
Discussion
Dyer Island is a small reserve, and the seabird population is
unable to withstand disturbances or threats that a larger
island may be able to. Threats to the birds on Dyer Island
include predation by seals (AB Makhado, MCM, unpublished data), oiling, competition for fish with trawlers, and
disturbance through poaching activities. Continued avian
cholera outbreaks is potentially an unsustainable additional
mortality factor for Cape cormorants.
Since recorded in September 2002, avian cholera
outbreaks on Dyer Island have occurred annually. The
mortality during these outbreaks appears to increase, with
mortality higher each year. This may be a function of an
increase in density of breeding birds, because more Cape
cormorants were counted during 2004/05 than the previous
year (Table 1). The low mortality during 2005/06 compared
with that of the previous year was unexpected, given that
Cape cormorants bred in similar densities to that of the
previous year. This could possibly be on account of them
having built up an immunity as a result of exposure to previous outbreaks. Alternatively, the island staff may have
been able to reduce the extent of the outbreak owing to increased vigilance and rapid removal of carcasses.
It is unclear as to why these avian cholera outbreaks
have persisted in Cape cormorants on Dyer Island. Some
studies suggest that the high mortalities during incubation
may be as a result of the weakened condition of incubating females who do not feed during this period (Korschgen
et al. 1978). Whereas most mortality on Dyer Island
occurs during the incubation period, both male and female
share in the feeding of chicks so this is unlikely the case
on Dyer Island.
It is also unclear as to what role avian cholera played in
the mortality of the juvenile Cape cormorants in 2004/05.
Laboratory results confirmed presence of P. multocida but
also indicated a presence of other bacteria, namely
Stretococcus spp. This may be the reason that mortality of
juveniles did not follow the similar mortality pattern of adult
Cape cormorants in 2004/05. Whereas it is difficult to determine the exact cause of death, presence of this bacteria is
often indicative of poor nutrition. It is unclear as to what role
the impact of direct avian cholera infection, natural juvenile
mortality, or reduced nutritional status due to food or
diseased stressed adults, have had in juvenile mortality
recorded in the colonies.
Outbreaks of avian cholera on Dyer Island have been
characterised by large mortality over a short period of time.
Experience on Dyer Island seems to correspond to that
found in other outbreaks, when the sooner carcasses are
removed from the island, the sooner the number of carcasses collected daily starts to decrease, and quick recognition of a potential outbreak is essential in an effective
clearing operation (Botzler 1991, Friend 1999).
109
The epizootics among Cape cormorants took place in
close proximity to groups of moulting and breeding African
penguins, breeding white-breasted, crowned and bank
cormorants, African black oystercatchers, kelp gulls, and
large numbers of roosting swift terns. Despite this, a
characteristic of the avian cholera outbreaks on Dyer
Island has been the single species mortality, with seemingly little impact on the other species. However, the
collection of carcasses is a high disturbance activity on
the island, regardless of the amount of care taken by the
island staff. During the collection of Cape cormorant
carcasses, some penguins moved off their nests, exposing their eggs and chicks to predation by kelp gulls. The
African penguin is a naturally burrowing bird, but is forced
to breed in surface nests on Dyer Island. This is as a
result of the guano scraping on the island, which has left
little burrowing habitat for this species. Guano scraping
took place almost annually from the commencement of
records in 1896 until 1973 (MCM, unpublished data). The
guano was scraped in five of the 12 years between 1974
and 1985, and has not been scraped subsequently.
However, since guano scraping ceased, the accumulation
of penguin guano has been minimal because the population size is small (Underhill et al. 2006). The numbers of
this vulnerable species have declined considerably on
Dyer Island. A project has been initiated to supply the
African penguins with artificial nests as a measure to not
only combat the effects of human-induced disturbance
created during avian cholera outbreaks, but also against
increased opportunistic kelp gull predation (Dyer Island
Conservation Trust in litt.).
In each of the three years, when the objective of
removal of all carcasses on a daily basis was reached,
mortality rates declined (Figure 2). Thus, the policy of
removal and incineration of carcasses did appear to be a
key factor in bringing the epizootic under control. Similar
findings have been reported elsewhere (Botzler 1991); and
the recommended policy in the USA is also to remove and
incinerate carcasses as a measure to control the spread of
avian cholera (Friend 1999). Survival of P. multocida is
enhanced by the presence of carcasses (Rosen and
Bishoff 1950, Olson and Bond 1968 and Titche 1979 as
cited in Botzler 1991, Price and Brand 1984). The removal
of carcasses reduced scavenging by kelp gulls, which may
transmit the disease all over the island and possibly to
other sites (Botzler 1991, Wobeser 1997). There is a
trade-off between the disturbance caused by carcass
collection and the likely further spread of the disease,
possibly to other sites (Botzler 1991, Wobeser 1997) if
carcasses are not collected.
Acknowledgements — We thank the management at CapeNature’s
Walker Bay office for logistical support during the outbreaks. The
Walker Bay and De Mond field rangers are especially thanked for their
assistance in collecting, counting and burning of carcasses: specifically
Pietie Simons, Penelope Michels, Mariëtte Lintnaar, Nico Barry, Johny
Brander and Dolf Europa. Dyer Island Cruises are thanked for their
logistical assistance during the outbreaks. The Avian Demography Unit
and Marine and Coastal Management are thanked for providing information on bird counts and assisting in the carcass collecting process.
Dr Jonker at the Department of Agriculture, Western Cape Provincial
110
Veterinary Laboratory, Stellenbosch, is also thanked for her advice on
bird dissections, and the bacterial and virology analyses conducted. Dr
Marienne de Villiers provided invaluable comments. LGU acknowledges
funding from the Sea and Coast ll Programme of the National Research
Foundation and from the Earthwatch Institute. This paper is a contribution to the project LMR/EAF/03/02 of the Benguela Current Large
Marine Ecosystem (BCLME) Programme.
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African Journal of Marine Science 2007, 29(1): 105–111
Appendix: Daily numbers of dead Cape cormorants collected (and ultimately) incinerated each day during the 2003/04, 2004/05 and
2005/06 outbreaks of avian cholera on Dyer Island, Western Cape, South Africa. The shaded blocks indicates the first day the entire island
was cleared of carcasses
2003 /04
Date
28 Dec
29 Dec
30 Dec
31 Dec
01 Jan
02 Jan
03 Jan
04 Jan
05 Jan
06 Jan
07 Jan
08 Jan
09 Jan
10 Jan
11 Jan
12 Jan
13 Jan
14 Jan
15 Jan
16 Jan
17 Jan
18 Jan
19 Jan
20 Jan
21 Jan
22 Jan
23 Jan
24 Jan
25 Jan
26 Jan
27 Jan
28 Jan
29 Jan
30 Jan
31 Jan
01 Feb
02 Feb
03 Feb
04 Feb
05 Feb
Total
2004 /05
Number
of
juveniles
700
683
735
450
520
404
316
316
352
381
158
91
43
43
37
20
0
1
18
11
7
9
9
5
5
3
5
1
7
2
3
0
0
4
7
5
0
3
0
1
5 355
Date
Number
of
adults
02 Oct
03 Oct
04 Oct
05 Oct
06 Oct
7 0Oct
08 Oct
09 Oct
10 Oct
11 Oct
12 Oct
13 Oct
14 Oct
15 Oct
16 Oct
17 Oct
18 Oct
19 Oct
20 Oct
21 Oct
22 Oct
23 Oct
24 Oct
25 Oct
26 Oct
27 Oct
28 Oct
29 Oct
30 Oct
31 Oct
01 Nov
02 Nov
03 Nov
04 Nov
05 Nov
06 Nov
07 Nov
08 Nov
09 Nov
10 Nov
11 Nov
12 Nov
13 Nov
174
169
1 203
1 978
1 325
2 252
1 241
245
215
188
161
147
93
94
35
49
40
27
14
9
8
12
21
12
3
1
1
0
8
0
2
0
0
0
0
0
0
2
0
0
1
1
2
Total
9 733
2005 /06
Date
Number
of
juveniles
23 Nov
24 Nov
25 Nov
26 Nov
27 Nov
28 Nov
29 Nov
30 Nov
01 Dec
02 Dec
03 Dec
04 Dec
05 Dec
06 Dec
07 Dec
08 Dec
09 Dec
10 Dec
11 Dec
12 Dec
13 Dec
14 Dec
15 Dec
16 Dec
17 Dec
18 Dec
19 Dec
20 Dec
21 Dec
22 Dec
23 Dec
24 Dec
25 Dec
26 Dec
27 Dec
28 Dec
29 Dec
30 Dec
31 Dec
99
123
70
409
449
289
250
218
127
262
163
173
156
294
464
301
362
257
123
88
32
19
4
7
4
11
3
6
9
7
3
0
0
6
1
0
0
5
0
4 794
Date
15 Oct
16 Oct
17 Oct
18 Oct
19 Oct
20 Oct
21 Oct
22 Oct
23 Oct
24 Oct
25 Oct
26 Oct
27 Oct
28 Oct
29 Oct
30 Oct
31 Oct
01 Nov
02 Nov
03 Nov
04 Nov
05 Nov
06 Nov
07 Nov
08 Nov
09 Nov
10 Nov
11 Nov
12 Nov
13 Nov
14 Nov
15 Nov
16 Nov
17 Nov
18 Nov
19 Nov
20 Nov
21 Nov
22 Nov
23 Nov
24 Nov
25 Nov
26 Nov
27 Nov
28 Nov
29 Nov
30 Nov
01 Dec
02 Dec
03 Dec
04 Dec
05 Dec
Number Number
of
of
adults juveniles
3
3
2
1
1
1
2
2
4
2
1
3
4
3
5
11
3
14
11
3
3
33
26
17
15
15
9
8
7
11
6
4
11
4
Date
06 Dec
07 Dec
08 Dec
09 Dec
10 Dec
11 Dec
12 Dec
13 Dec
14 Dec
15 Dec
16 Dec
17 Dec
18 Dec
19 Dec
20 Dec
21 Dec
22 Dec
23 Dec
24 Dec
25 Dec
26 Dec
27 Dec
28 Dec
29 Dec
30 Dec
31 Dec
01 Jan
02 Jan
03 Jan
04 Jan
05 Jan
06 Jan
07 Jan
08 Jan
09 Jan
10 Jan
11 Jan
12 Jan
13 Jan
14 Jan
15 Jan
16 Jan
17 Jan
18 Jan
19 Jan
20 Jan
21 Jan
22 Jan
23 Jan
24 Jan
25 Jan
26 Jan
Number Number
of
of
adults juveniles Date
9
5
1
5
13
28
15
22
22
1
15
17
15
13
10
17
3
88
115
110
76
90
41
11
20
34
1
8
4
8
10
9
7
1
1
27 Jan
28 Jan
29 Jan
30 Jan
31 Jan
01 Feb
02 Feb
03 Feb
04 Feb
05 Feb
06 Feb
07 Feb
08 Feb
09 Feb
10 Feb
11 Feb
12 Feb
13 Feb
14 Feb
15 Feb
16 Feb
17 Feb
18 Feb
19 Feb
20 Feb
21 Feb
22 Feb
23 Feb
24 Feb
25 Feb
26 Feb
27 Feb
28 Feb
01 Mar
02 Mar
03 Mar
04 Mar
05 Mar
06 Mar
07 Mar
08 Mar
09 Mar
10 Mar
11 Mar
12 Mar
13 Mar
14 Mar
15 Mar
16 Mar
17 Mar
Total
Number Number
of
of
adults juveniles
3
1
1
1
2
1
8
1
2
1
4
2
352
763