Forestry Commission
Black Grouse and Forestry:
Habitat Requirements and Management
John Cayford
1
Forestry Commission
ARCHIVE
Technical Paper 1
FORESTRY COMMISSION TECHNICAL PAPER 1
Black Grouse and Forestry:
Habitat Requirements and Management
John T. Cayford
Research Biologist,
The Royal Society for the Protection of Birds
FO R E ST R Y C O M M ISSIO N , ED IN BU RG H
1
Summary
The black grouse is a large, sexually dim orphic species found typically in habitats
transitional betw een m oorland and forest. N um bers of black grouse have recently
declined throughout m uch of Europe. In Britain, the species is now largely confined
to Scotland, the north of England and W ales. Continued loss and fragm entation of
habitat represents the m ost serious threat to black grouse. Research suggests that
b lack g rou se w ou ld b e fav o u red by sy m p a th etic m a n a g em en t p ra ctices w h ich
conserve existing h abitat in forests and on ad jacent m oorland. Black grouse use
forestry plantations prior to canopy closure, resulting in local, short-term increases in
n u m b e rs an d ra n g e . T h is T e c h n ic a l P a p e r g iv e s r e c o m m e n d a tio n s fo r th e
m anagem ent of black grouse in coniferous forests together with a description of the
species, its current distribution, status and critical habitat requirem ents.
Black Grouse and Forestry:
Habitat Requirements and Management
Description
Black grouse Tetrao tetrix L., or blackgam e, are striking
birds best know n for the elaborate displays of m ales on
com m unal 'leks' in spring (Lack, 1939; Johnstone, 1969;
Vos, 1983). The m ale (blackcock) w eighs approxim ately
1250 g, is rou gh ly the size of a d om estic fow l and is
la rg e r th a n the red g ro u se (L ag op u s lag op u s L.) but
sm aller than the capercaillie (Tetrao urogallus L.). From
a d ista n ce the p lu m ag e o f m ales a p p ears b lack , but
close-up the upper parts are a glossy blue-black w ith a
scarlet w attle over the eye. A distinct w hite wing bar is
best seen w hen the bird flies. The underside of the lyreshaped tail is pure w hite and is p articu larly strikin g
w h en m ales d isp lay . In su m m er, m ales m ou lt their
feathers and the partial eclipse plum age is m ore mottled
with brown.
The fem ale black grouse (greyhen) is sm aller than
the m ale (w eighing approxim ately 950 g), but is larger
th a n th e red g ro u se . T h e p lu m a g e is v a ria b le b u t
generally a mottled faw nish and chestnut brow n, barred
w ith b la ck on the h ead . T h is g iv es a g rey er-b ro w n
a p p e a ra n c e co m p a re d to th e red g ro u se . T h e tw o
species can som etim es be distinguished in flight by the
profile of the tail w hich is forked in the black grouse,
but rounded in the red grouse. The greyhen also has a
w ing bar, although this is not as p rom inent as in the
male. The flight action of a greyhen is quite different
too, with deeper continuous wing beats com pared to the
shorter beats of red grouse which are interspersed with
glides. Fem ale capercaillie are 35% larger than female
black grouse and have no pale w ing bar.
Distribution and population density
B la c k g r o u s e a re w id e ly d is tr ib u t e d th r o u g h o u t
c o n tin e n ta l E u r o p e an d S ib e r ia , b u t n u m b e rs a re
declining over m uch of this range. In Britain they occur
in the m ore rem ote, upland parts of N orth W ales (Grove
et a l., 1 9 8 8 ), the m o o rla n d s an d ro u g h g ra z in g s of
northern England (G arson and Starling, 1990) and the
Peak D istrict (Sh arrock, 1976; Lovenbu ry et al., 1978;
Y ald en, 1986), but only in Sco tlan d are black grou se
n um erous over larg e areas (Thom , 1986; P icozzi and
C a tt, 1 9 8 8 ; H u d so n , 19 9 0 ; B a in e s, 19 9 0). T h e total
British population w as estim ated by Parslow (1973) to
be betw een 10 000 and 100 000 pairs. Both Sharrock
(1976) and Picozzi (1986b) consider the true figure to lie
at the low er end of this range.
T h e b la ck g ro u se h as d eclin ed in m an y p arts of
Britain over the last 100 years. Form erly widespread in
1
south-west England and in the east to Lincolnshire and
N o rfo lk it is now e x tin c t in th ese areas. L ess than
20 males remain in the Peak District (Yalden, 1986). In
northern England the population has undergone some
flu ctu atio n and at p resen t is thought to be stab le in
County Durham and parts of N orthum berland but may
be declining in parts of N orth Y orkshire (Garson and
S ta rlin g , 1990). T h e p o p u la tio n in W ales p a rtia lly
recovered, probably due to afforestation, after a decline
in the early p art o f this cen tu ry w h en b la ck grou se
b ecam e ex tin ct in G lam organ , M onm ou th and Flint.
Recent surveys in W ales showed a contraction of range
and a fall in num bers to less than 300 m ales by 1986
(G rove et al., 1988) w ith som e evid ence of continued
declines on leks in forests (Cayford and W alker, 1991).
In Scotland, shooting-bag returns from estates show a
75% reduction in the num bers of black grouse shot since
the 1930s and m arked differences in the m agnitude and
timing of this decline between regions (Hudson, 1990).
N u m b e rs h a v e s h o w n b o th s h o r t- an d lo n g -te rm
fluctuations, but are now thought to be relatively stable
a fte r a s u b s ta n tia l d e c lin e in the e a rly p art of this
century (Barnes, 1984). Recolonisation and colonisation
is apparent in some recently afforested areas and may
account for local population increases (Thom, 1986).
In com m on w ith other grouse species, some black
grouse populations undergo short-term fluctuations in
numbers. Tapper (1988) presents evidence based on bag
records in Scotland for population cycles with a peak at
a b o u t 5 -y e a r in te r v a ls b u t th is m ay be an a rte fa c t
because most black grouse are shot on red grouse drives,
an d so m e red g ro u s e n u m b e rs sh o w c y c lic a l
flu ctu atio n s. V ario u s in trin sic (self-reg u lato ry ) and
e x trin sic (p re d a tio n , p a ra site s, w ea th er co n d itio n s,
habitat deterioration, etc.) factors have been proposed
to account for cyclical changes in other grouse species.
For exam ple, in northern and central Scandinavia and
Finland short-term fluctuations of grouse populations
have opposite trends to those of sm all mammals. W hen
v o le p o p u la tio n s 'c r a s h ', p r e d a to r s s w itc h th e ir
a tte n tio n to g ro u n d n e s tin g b ird s su ch as g ro u se
(Angelstam, 1984).
The main threat to black grouse appears to be loss
and fragm entation of habitat with resulting isolation of
populations (Cayford, 1990b). Other factors which have
been shown to suppress num bers include egg and chick
predation, disturbance (especially during the breeding
s e a s o n ), s h o o tin g p r e s s u r e and p o s s ib le co ld w et
w eather during the early fledging period which reduces
the availability of insects to chicks.
(A)
a)
Figure 1. H abitat use and preferences of radio-tagged m ale black grouse at Penaran in W ales. V alues show n are percentage of
observations ± 957c confidence lim its in forest stands of different canopy cover (A) and height (B) com pared w ith expected values
based on random sam ples observed (n=252 A), (n=226 B), and expected (n=330 A), (n=333 B). H orizontal bar: closed = significant
preference, hatched = no preference, open = significant avoidance. (Redraw n from Cayford et al., 1989).
Habitat requirements
The ancestral habitats of black grouse were probably in
th e b o r e a l an d s u b - a r c t ic fo r e s ts o f th e n o r th e r n
h em isp h ere w h ere fire and w ind d am ag e created a
m o saic o f o p e n in g s and y o u n g s u c c e ssio n a l sta g es
which the birds could colonise. These natural forests
provided food in the form of dw arf shrubs, birch buds
and catkins and berries together with shelter, nest sites
and u nd istu rb ed lekk in g aren as. Sim ilar con d itio n s
exist today in som e native Scots pine (Pimts sylvestris)
forests in Scotland, but most habitats of black grouse in
Britain are of m ore recent origin and greatly influenced
by m an's activity.
The p resen ce of trees is g en erally b eliev ed to be
essential for black grouse (Johnsgard, 1983). H owever,
som e pop u lation s in n orth ern England and Scotland
survive in relatively treeless areas. Studies in northern
Sw eden have shown that black grouse prefer stands of
5-8 m in height and avoid those <4 m or >12 m high
(M arcstrom et al., 1982). H owever, tree density is often
m ore critical than height because this affects the speed
of can op y clo su re and the sh ad in g out of im p o rtan t
eric a ce o u s food p lan ts (C ay fo rd et a l., 1989). M o st
forests in upland Britain are com prised largely of fastgrow ing, coniferous species, particularly Sitka spruce
(P icea sitch en sis), p lanted at high d en sity in uniform
stands. Research in W ales revealed that black grouse
2
Calluna vulgaris
Arthropoda
0
B
0
0
60
o_
k
O
J
F M A M
J
J A S O N D
Month
Figure 2. Seasonal changes in the diet of adult black grouse in coniferous forests in W ales. Values show n are means. (Redrawn
from Cayford, 1990c).
showed the greatest preference for plantations with 1540% can o p y cov er w h ich p ersisted in sm all p atch es
w h ere the p lan ted crop had failed (C ayford , 1990c).
Birds g en erally avoided thickets w here canopy cover
exceeded 70% (Figure 1).
T h r o u g h o u t th e y e a r b la c k g r o u s e r e q u ir e a
su ccessio n o f d ifferen t h ab itats for a ctiv ities such as
feed in g , d isp la y in g , n estin g , roo stin g and m ou lting.
The num ber of m ales at a lek reflects the availability of
these different h abitat com ponents w ithin a radius of
approxim ately 2 km of the lek.
Display areas
Black grouse m ales are polygam ous (m ate with several
fem a les) and p lay no p a rt in rea rin g you n g. M ales
d isp lay com m u n ally and m ate on trad itio n al aren as
3
(leks) w here they advertise their social status through
cerem onial defence of a small area of the lek. Dominant
m ales tend to occu p y a cen tral cou rt on the lek and
attract more fem ales (Johnstone, 1969; Kruijt et al., 1972).
M ales atten d lek s th ro u g h o u t the year excep t w hen
m ou lting, but the m ain period of activ ity is betw een
M arch and June, and in som e areas, in late Septem ber
and O cto b er (K o iv isto , 1965; H jo rth , 1968). A rrival
tim es at the lek can vary but in W ales m ales arrive
approxim ately 90 minutes before sunrise in mid-March
and leave the lek an hour after sunrise. By the end of
M ay in W ales, the first m ales arrived as early as 0300
hrs, but m ost birds had left the lek by 0430 hrs (Cayford
and W alk er, 1991). It is qu ite com m on for b ird s to
return at dusk, particularly in April and May.
The bubbling, dove-like 'cooin g' or 'rookoo' sounds
m ade by sev eral m ales as they d isp lay can often be
Bilberry / Blaeberry
(Vaccinium m yrtillus)
Heather
(Calluna vulgaris)
100
C0
o
o
03
D
Q.
03.
0
C/3
J FMAMJ JASOND
J FMAMJ J A S O ND
Month
% diet
|
>51 % 0 26 -50% g 1-25% g 0
Figure 3. Seasonal changes in the percentage com position of heather and blaeberry in the diets of black grouse in Scotland (upper)
and W ales (lower). (Redraw n from Cayford et al., 1989 and Picozzi and H epburn, 1984).
heard 1-2 km from the lek on a still m orning and can be
used to locate leks. The lek usually consists of an area
of relatively flat, open ground w ith sh ort v egetation
(less than 5 cm in height) and good all round visibility.
The total area used for display rarely covers m ore than
about 0.5 ha, but the lek is alw ays sited in a m uch larger
expanse of open ground. Peat bogs, pasture, m oorland
adjoining forest, open glades, forest rides and roads,
and clear felled areas can all be used. Leks tend to be on
the sa m e s ite s y e a r a fte r y e a r , b u t m ay m o v e if
vegetation encroaches or there is sustained disturbance.
Diet and feeding areas
In B rita in the d iet of b la ck g ro u se h as la rg ely been
determ ined by faecal analysis. Adult black grouse feed
on a variety of seasonally available vegetation and also
take som e insects in sum m er (Figure 2). Leaves, stems,
buds, flow ers, seeds and fruits of several dw arf shrub
sp ecies are eaten , d ep end ing on lo cality , season and
a v a ila b ility . T h e b u d s o f la rc h , S c o ts p in e , b irc h ,
ju n ip er, row an and haw thorn, together w ith fruits of
row an and haw thorn are also taken. M ost feeding is
done on the ground but birds will feed on larch buds in
4
Night
Percent observations
60
Day
Percent observations
20
40
40
60
Stand Habitat
1
........................................................ / / / / / / / / / / / / / / / / / / 77m
LWWWWWWWWWWVVWVVVVVVVS
~~
wKK/K/M/ / / / / A
2
Forest
3
4
■ 21
Site 1
m
Site 2
Ride / Road
7m
5
Zd
fj] Moorland
i7zm
7 ] Grass
Figure 4. H abitats utilised by ratio-tagged broods at two sites in N orth W ales during the day (site 1 n=45, site 2 n=5) and at night
(site 1 n=22, site 2 n=14). H abitat categories: 1 = young conifers (height 0.5-1.3 m ), 2 = young conifers (height 1.3-3 m), 3 = thinned
m iddle-aged stand (average stem diam eter of 10-20 cm at breast height), 4 = forest ride, 5 = forest road-side verge, 6 = wet
m oorland (dam p, heather d om inant but including Nardus, Scirpus, Eriphorum, Molinia and Sphagnum), 7 = grass (>50% cover),
Nardus/Molinia dom inant. (Redraw n from Cayford et al., 1989.)
spring and birch catkins and the buds of Scots pine in
late w inter. D uring periods of prolonged snow cover
th e a v a ila b ility o f tree b u d s m ay b e c ritic a l to the
condition of the bird and m ay thus influence breeding
success and in som e instances survival (Picozzi, 1986a).
E ric a c e o u s sh ru b s, p a rticu la rly h ea th e r ( C allu n a
vulgaris) and blaeberry (bilberry) (Vaccinium m yrtillus)
are im p o rta n t food p la n ts th ro u g h o u t the y e a r and
formed the bulk of the diet of black grouse in Scotland
(P ic o z z i, and H e p b u rn , 1984) and W a le s (C a y fo rd ,
1990c). H eather predom inates over blaeberry in the diet
of m oorland black grouse studied in Scotland (Picozzi,
1986a), w hereas blaeberry is favoured by birds in W ales
(Figure 3). From M arch to M ay, both sexes m ay feed
a lm o s t e x c lu s iv e ly on la r c h b u d s a n d th e n e w ly
em ergent flow er heads of the cotton grass (Eriophorum
v a g in a t u m ) . In n o r th e r n E n g la n d , h e rb s su c h as
T rifoliu m sp p ., R u m ex spp . and R an u n cu lu s spp . are
im p o rtan t sp rin g food s (B ain es, 1990). In su m m er,
b e rrie s, in se cts and seed s o f g ra sses and sed g es are
taken.
C h ic k s le s s th a n 3 w e e k s o ld a re fe d a lm o s t
exclu sively on arthropod s (see K astdalen and W egge,
19 8 6 ; P ic o z z i, 1 9 8 6 a ; C a y fo rd et a l., 1989; C a y fo rd ,
1990c). A w ide range of insects and spiders were taken
according to local abundance and ease of capture, but
an ts and the larv ae of L ep id op tera and saw flies are
num erically the m ost im portant item s (Picozzi, 1986a;
Cayford et al., 1989). O ther insect orders w hich were
tak en in c lu d e h a rv estm en , beetles, spid ers and flies.
5
Chicks older than 3 weeks take fewer insects and more
berries and heather leaves.
Radio telem etry studies in Scotland (Robel, 1969a;
Picozzi and Hepburn, 1986) and Wales (Cayford et al., 1989;
C ayford, 1990c) have show n that black grouse select a
variety of open, sem i-natural habitats for feeding, but
generally prefer an open patchwork of young, or widely
spaced older trees with a well developed understorey of
young heather, blaeberry or cotton grass. In Scotland, males
were found mainly in open mature woodlands in winter,
whereas hens favoured very small clumps of regenerating
pine on m oorland and both sexes were found on open
ground in the summer and autumn (Picozzi, 1986a; Baines,
1990). In coniferous forests in Wales the preferred foraging
habitats were young plantations, thinned older stands, open
enclaves, forest rides and exposed ridges with a patchwork
of uneven-aged trees and open glades (Cayford et al., 1989;
Cayford, 1990c). Com parisons of habitats in the vicinity
of leks in northern England suggest that sheepwalk and
young coniferous forest were preferred habitats (Garson
and Starling, 1990).
Chick rearing areas
T h e h a b ita t o f h e n s in su m m e r is d e te r m in e d by
requirem ents for nesting and rearing young. Eggs hatch
synchronously usually in m id-June and young are led
from the nest w ithin 24 hours of hatching. Broods travel
successively further from the nest site during the first 23 w eeks b efore settlin g into hom e ranges of 30-60 ha
(Wegge et al., 1982). The first 10 days after hatching are
the m ost critical for chick survival. The condition of
hens m ay influence chick survival, but w et w eather and
the availability of food are m ore im portant. The quality
of the brood habitat can be of param ount im portance in
influencing brood survival.
H en s w ith b r o o d s a v o id th ic k e ts , d ry h e a th e r
m oorland and heavily grazed farm land, but p refer a
v a rie ty o f h a b ita ts w h ich su p p o rt h ig h d e n sitie s of
in s e c t fo o d s an d p r o v id e c o v e r fro m p r e d a to r s
(m u s te lid s , fo x e s and r a p to rs ). W e t, ru sh y m ire s
(ungrazed by sheep) were preferred by chicks less then
3 weeks old on heather moorland in Scotland (Parr and
W atson, 1988) w hereas stream m argins, sunny rides,
verges and young plantations supporting a m ixture of
tall g r a s s e s , h e a th e r and b la e b e r ry w ere fa v o u re d
h a tita ts in b ro o d s in fo re sts in S co tla n d and W ales
(Picozzi, 1986a; C ayford et al., 1989; C ayford , 1990c)
(Figure 4).
Nesting and roosting sites
M ating occurs on the lek and the fem ales usually nest
within a 2 km radius (W illebrand, 1988). The 6-11 eggs
(8 is average) are larger, but less heavily m arked than
those of the red grouse and are laid on alternate days in
a shallow scrape, lined w ith grass or m oss. Eggs are
laid in late April-early June and hatch in approxim ately
26 days (Cramp and Sim m ons, 1980). The fem ale selects
a dry, nest site with tall (greater than 35 cm and up to 54
cm ), d en se v eg etation or som e oth er form o f sh elter
such as an uprooted tree, which offers protection from
w e a th e r an d c o n c e a lm e n t fro m p r e d a to r s d u r in g
incubation. Tall, rank heather, dense blaeberry, rushes
and bracken are particu larly favoured as nesting and
roosting sites (Cayford et al., 1989).
Habitat scale
Little inform ation exists on the area of suitable habitat
needed to support a self-sustaining population of black
grouse. Estim ation of the area used by individual birds
is an im portant prerequisite to a better understanding of
habitat use and m anagem ent. Johnstone (1969) found
th a t h o m e ra n g e s o f le k k in g m a le s in n o r th -e a s t
Scotland w ere about 500 ha. R obel (1969a) rep orted
ranges of 303-689 ha with a m ean of 458 ± 126 (SD) ha
and Picozzi (1986a) obtained ranges of 355 ± 178 ha for
m ales, 85.8 ± 37.3 ha for m oorland fem ales and 44.9 ±
28.3 ha for w oodland fem ales. It appears that once a
hen has bred it seldom m oves far from that general area
(P ico zzi, 1986a). In co n ifero u s p la n ta tio n s in W ales
hom e ranges of radio-tagged m ales averaged 325 ± 71
ha (Cayford, 1990c). H om e ranges of m ales attending
the sam e lek overlapped considerably and were discrete
from m a les a tte n d in g a d ja ce n t lek s. M ales did n ot
appear to m ove betw een leks. These data confirm that
black grouse are largely sedentary and suggest that an
area of 5 0 0 -7 0 0 ha o f su ita b le fo re st and m o o rlan d
habitat m ay be enough to sustain one lek.
Black grouse in British forests
B la c k g ro u se o cc u p y so m e s e m i-n a tu r a l fo re s ts in
S co tlan d , p a rticu la rly of p in e and b irch (G lad sto n e,
1924; Jo h n sto n e , 1969; R o b el, 1969a, 1969b ; P ico z z i,
1986a, 1986b; Parr and W atson, 1988) but in m ost other
a re a s th e y a re m a in ly a s s o c ia te d w ith c o n ife r o u s
plantations, as in W ales (Grove et al., 1988; Cayford et
al., 1989), and patch w orks of sem i-n atu ral vegetation
su ch as h eath e r m o o rlan d and u n im p ro v ed p astu re
in te rs p e rs e d w ith w o o d s, h e d g e ro w s o r g ro u p s of
b r o a d le a v e d tr e e s . P o s t-w a r a f f o r e s ta t io n in th e
uplands has reduced the range of som e birds dependent
on moorland (Avery and Leslie, 1990; Petty and Avery,
1990), but black grouse often benefit, in the short-term ,
follow ing planting. Under relaxation from grazing and
burn in g, dw arf shrubs such as heather and blaeberry
spread and b ecom e lu xu rian t, so providing food and
n e s tin g c o v e r. M o re o v e r th e y o u n g tre e s an d th e
d ev elo p in g grou nd v egetation provide sh elter, cover
from predators, and in som e cases w inter food until the
canopy closes.
Effects o f changes in the age-class o f forests
In the early grow th stages after afforestation there is an
in creasin g am ou n t o f sem i-n atu ral v eg etatio n w hich
black grouse can exploit. A fter 10-15 years conditions
rapidly d eteriorate for black grouse as the trees close
canopy and suppress the grow th of understorey shrubs.
L o ss o f g ro u n d v e g e ta tio n d u e to sh a d in g is m o re
pronounced in spruce as opposed to pine plantations
(Hill, 1979). By the tim e the canopy has closed (thicketstage), these young plantations are largely unsuitable
for b lack g rou se, alth o u g h they m ay still be used in
w inter or as a refuge follow ing disturbance and black
grou se m ay feed on larch buds in the spring. By the
th ick e t sta g e, su ita b le h a b ita t is m ain ly co n fin ed to
unplanted rocky outcrops and m oorland patches, areas
o f w indthrow , stream m argins, rides, road-side verges
and the interface betw een forest and m oorland (Cayford
and H ope Jon es, 1989). In upland Britain large areas
have been afforested during a short tim e span, resulting
in the h a b ita t q u ality for b la ck g ro u se d eterio ratin g
q u ic k ly o v er e x te n siv e area s as cro p s p ass in to the
thicket stage.
C iear felling recreates open space in the forest which
b la c k g r o u s e c a n e x p lo it if a d w a r f s h ru b la y e r
develops. In the long-term , clear fellin g can create a
m osaic of d ifferen t-aged crops w hich m ay p rovid e a
co n stan t su p p ly of su itab le h abitat. In W ales, b lack
g r o u s e fe e d an d r o o s t in fe lle d an d r e p la n te d
(restocked) areas w here heather and blaeberry have re­
established, but avoid those which have becom e choked
w ith grass and bram ble. H eather seed persists in the
soil through the first rotation and at clear felling it can
regenerate over large areas. H ow ever, w hen trees are
planted w ithin a year of felling, heather m ay not have
tim e to regenerate from seed and reach a suitable height
6
(A)
(B)
Percent underestimate
Hours either side of sunrise
Figure 5. D eviations in the num bers of m ale black grouse counted on individual leks in W ales by (a) season and (b) time in AprilM ay. V alues show n are the average extent to w hich a single count deviated from the seasonal m axim um count. (Redraw n from
Cayford and W alker, 1991.)
to provide both cover and food for black grouse. Clear
felling should not be seen as a substitute for, but as an
a d d itio n to, the p ro v isio n of m ore p erm an en t b lack
g rou se h a b ita ts w ith in forests. D iv ersify in g the age
structure of a forest at the end of the first rotation by
patchw ork clear felling will im prove the area for black
grouse providing heather is allow ed to regenerate on
restocked sites. H ow ever, other m easures will also be
required.
S u rv e y in g and m o n ito rin g b la ck
grouse populations in forests
A nnual counts of black grouse give the forest m anager
d ata on d istrib u tio n and d en sity ov er tim e, ag ain st
7
which the effectiveness of m anagem ent practices can be
gauged. Tw o main census techniques are used for black
g ro u se, these in v o lv e eith er co u n tin g m ales on leks
(G ro v e et a l., 1 9 8 8 ; C a y fo rd and W a lk e r, 1991) or
co u n tin g b ird s alo n g tran sects u sin g p o in tin g dogs
(Baines, 1990). The latter requires highly trained dogs
which limits the use of this technique to forests where
su itab le dogs are av ailab le. Lek cou nts p rovid e the
sim plest way of counting black grouse in a forest. Not
all m ales display com m unally, so it is im portant that
b ird s d isp lay in g so litarily are also located . So litary
d isp lay sites m ay be used for ju st one or tw o years
c o m p a re d to th e r e g u la r u se o f t r a d itio n a l le k s.
H ow ever, con iferous forests are dynam ic habitats, so
new lek sites can be established and used over a few
years when the habitat is suitable.
8 1
<D
7
-
6
-
5
-
4
-
'E
<u
E
i-
3
2
-
i—
March
April
May
June
Month
Figure 6. Seasonal changes in lek attendance by m ale grouse in W ales. V alues show n are m eans ± 1 S.E. (Redraw n from Cayford
and W alker, 1991.)
T h e d iu r n a l tim in g o f le k c o u n ts s h o u ld b e
sta n d a rd ise d b e ca u se n u m b ers v ary w ith tim e and
season (Figure 5) with m ales arriving on leks earlier as
the season progresses (Figure 6) (H jorth, 1968; Cayford
and W alker, 1991). C ounts should id eally take place
one h o u r e ith e r sid e of su n rise , no e a rlie r th an the
second week in April and no later than the second week
in M a y . A s an e x a m p le , a t h r e e - t ie r m o n ito r in g
p ro g ra m m e has b een p ro p o se d fo r b la ck g ro u se in
W ales. This involves an extensive survey every sixth
y e a r, b ia n n u a l m o n ito rin g o f a ll le k s an d s o lita ry
d isp lay sites in the h ig h est d en sity area, and annual
su rv ey s by Forestry C om m ission ran g ers in selected
forest blocks (Cayford and W alker, 1991). W illebrand
(1988) noted that fem ales arrived on leks for m ating
during a 6-8 day period, usually in the first 2 weeks of
May, w hile in Scotland they visited leks from m id-April
onw ards (Picozzi, personal com m unication).
Improving forests for black grouse
The future of black grouse in Britain depends largely on
the availability of suitable habitat. Forests can play an
im portant part. The prim ary objective of m anagem ent
fo r b la c k g ro u se is to e n s u re th a t a ll th e ir h a b ita t
req u irem en ts are m et through out the forest rotation.
T h e fo llo w in g re c o m m e n d a tio n s aim to p ro d u ce a
m o sa ic o f v e g e ta tio n ty p e s b y c o n s e r v in g e x is tin g
h abitat and creating areas of sem i-perm anent habitat.
Em phasis has been placed on m anagem ent of existing
open areas and the creation of new ones.
M anagement areas centred on leks
Both m ale and fem ale black grouse rem ain in the same
general locality throughout the year and rarely m ove
m ore than a few kilom etres from the lek they attend in
spring. Therefore, it is recom m ended that m anagem ent
im provem ents should first be targeted w ithin a 1.5 km
(707 ha) radius of know n leks and largely concentrate
on:
1. the edges of forests which border m oorland;
2. clear felled and restocked sites;
3. recently afforested sites;
4. unplanted m oorland rem nants within the forest.
C onsideration m ay also be given to creating suitable
conditions for colonisation or re-colonisation by black
g r o u s e in f o r e s t s le s s th a n 15 km fro m e x is tin g
pop ulations. H ow ever, this is of low er priority than
developin g a m anagem ent strategy based on existing
strongholds.
Forests should be ranked in order of im portance for
black grou se on the basis of sound su rv ey data from
leks. A reas w ith le k s sh ou ld b e ran k ed on th e size
(num ber of cocks) and num ber of leks and the best areas
d esig n ated as B lack G ro u se M an agem en t A reas and
in corp orated in to C o n serv atio n Plan s. A larg e-scale
8
m ap show ing the m anagem ent requirem ents within the
d esignated area and the tim e-scale of operations w ill
ensure continuity in the event of personnel changes.
T h e fo llo w in g s e c tio n s g iv e a d v ic e on h o w to
im prove the quality of various habitats for black grouse
w ithin Black Grouse M anagem ent Areas.
Lek sites
The area of the lek needs to be kept open. On some sites
th is m a y r e q u ir e p e r io d ic m o w in g o r c le a r in g o f
invading vegetation w hile others m ay be developed as
deer glades or grazed by dom estic stock. M ow ing or
cutting-back should take place betw een N ovem ber and
Ja n u a ry w h en a tte n d a n c e at le k s is in fre q u e n t. To
p r o v id e a d e q u a te flig h t p a th s an d s e c u r ity fro m
predators, no trees should be planted within 50 m of the
lek and it m ay be n e c e ssa ry to fe ll trees w ith in the
distance to retain the openness of the lek. All form s of
distu rbance should be m inim ised, particularly during
the April/M ay period. The location of lek sites should
not be m ade w idely available. H ow ever, at some well
know n leks disturbance from people could be reduced
by providing an observation hide w ith sheltered access.
Young plantations
New forests should be designed w ith m any open areas
con sistin g of ericaceou s vegetation and dam p, boggy
areas w hich greatly benefit black grouse. These areas
should be linked by w ide rides or rip arian zones. In
forests in the pre-thicket stage, m anagem ent should be
directed tow ards m aintaining habitats that are preferred
by b lack grou se. For exam p le, su nny riv er m argins,
rid es, road -sid e verges, bog g y areas and open areas,
ro c k y o u tc r o p s a n d r e s p a c in g c r o p s w ith g o o d
ericaceous vegetation. In forests in the thicket stage and
b e y o n d , w h e re m u ch o f th e s u ita b le b la c k g ro u se
h a b ita t has d isap p eared , the em p h asis sh ou ld be on
p r e s e r v in g n e s tin g an d c h ic k -r e a rin g h a b ita ts and
c re a tin g n ew h a b ita t, by p re m a tu re c le a r fe llin g or
respacing.
Forest edges adjacent to moorland and marginal
farmland
Forest/moorland edges could be dramatically improved
for black grouse by providing a graded interface instead
o f a h a rd d iv is io n b e tw e e n c lo se -sp a c e d trees and
m oorland. This can be achieved in a num ber of ways.
First, do not plant up to the perim eter fence for all its
le n g th . L e a v e u n p la n te d la rg e a re a s o f e ric a ce o u s
v eg eta tio n and w et flu sh es on the fo rest sid e of the
fence. Second, use variable spacing to grade the forest
into the adjacent m oorland. The aim should be to create
a t th e en d o f th e f ir s t r o ta tio n a m ix tu r e o f tre e s
interspersed w ith a variable patchw ork of open areas
w h ere the ex istin g grou nd v eg etatio n p ersists. This
grading should extend up to 200 m into the forest on
areas that have been carefully selected to benefit black
grouse. Third, by the w ider use of other trees such as
Scots pine, larch and birch to provide alternative species
9
to brow se during periods of heavy snow cover. Scots
pine and birch are very useful species, as they cast a
m uch lighter shade than spruce or larch and often allow
ericaceous vegetation to survive even during the thicket
stage, particularly when the initial planting distances
are increased.
A num ber of m anagem ent practices could favour
b la c k g ro u se on m o o rla n d an d m a rg in a l farm lan d
adjacent to forests. In northern England black grouse
select improved in-bye fields in spring, rough grazings
in sum m er and hay meadows in autum n, emphasising
th e im p o rta n c e o f lo w -in te n s ity a g ric u ltu r a l lan d
adjacent to forests. Drainage and re-seeding has led to a
reduction in the am ount of traditionally managed herb
an d s e d g e ric h m e a d o w s an d a s s o c ia te d flu s h e s
favoured by adults prior to breeding and broods (Parr
and W atson, 1988). In Scotland, black grouse feed in
field s of rape, clover, grass and herbs and up to the
early 1970s flocks of both sexes fed on oats on stubbles
(Parr and W atson, 1988). A gricultural intensification
has reduced the am ount of m arginal habitat suitable for
b la ck g ro u se , b u t if so m e o f the p ra ctice s w ere re ­
established on a small scale, it could provide additional
food for black grouse.
A fe a tu r e o f h e a th e r is th a t th e g re e n sh o o ts
preferred by grouse becom e less nutritious as the plant
a g e s an d m o re o f th e p la n t b e c o m e s w o o d y . To
im prove food quality for red grouse, heather has been
burnt in strips and patches when the plants are 15-20 cm
high, to produce fresh new growth. This practice will
alm ost certainly benefit black grouse, so long as some
areas are burnt less regularly to provide older plants for
cover, roosting, m oulting and nesting. Blaeberry will
a lso th riv e in area s o f o ld er h eath er or u n d er trees
which cast a light shade.
Burning heather is often too risky along the edge of
forests, but m echanical cutting provides an alternative
m eans of regenerating heather. Black grouse and red
grou se used cut strip s o f m oorland m ore than uncut
area s th ro u g h o u t the y ear in W ales (C ayford et al.,
1989). C u ttin g is b est d on e in late autum n or early
spring along the edge of forests holding good stocks of
birds and the cut stems should be removed or they will
inhibit regeneration.
Riparian zones
T h e m a rg in s of riv e rs and stre a m s, m ires and w et
flu s h e s w h e re h e a th e r , b la e b e r r y and g ra s s e s are
present, are good feeding areas for adults and broods.
It is im portant to m aintain wide m argins around these
areas to prevent the shading out of food plants and give
e a sy a c c e s s to the b ird s . F o r e x a m p le , w h ere the
vegetation is su itable, at least 25-30 m should be left
unplanted on either side of w atercourses, but the wider
the better. Mires and wet flushes should not be drained
and w et in sect-rich areas can be created by blocking
d ra in s . It is d e s ir a b le to v ary the w id th o f th e se
u n p la n te d area s and to p ro v id e a g rad ed in te rfa ce
between the tree crop and the open area.
W h ere good ch ick rearin g h a b ita t is lo calised in
narrow strip s, predation can be m ore severe than in
m ore extensive open areas (Picozzi, 1986a). A m osaic of
wet flushes incorporated into w ide stream m argins with
g o o d c o v e r and no tre e s o ffe r s th e b e s t c h a n c e o f
survival. In areas less im portant for broods, a scattering
of birch, hawthorn, Scots pine or larch m ay be beneficial
as a so u rce of sp rin g and w in ter fo o d , b u t all trees
should be sufficiently well spaced or planted in groups
to reduce shading of the ground vegetation.
d u rin g r e s to c k in g as th e se h a b ita ts are m u ch le ss
co m m o n a fte r the e x te n s iv e d r a in a g e u n d e r ta k e n
d u rin g the fir s t r o ta tio n . N a tu ra l r e g e n e ra tio n of
c o n ife r s m ay n eed to b e cle a re d fro m w e t flu s h e s
periodically.
M onitoring the use o f Black Grouse
Management Areas
T h e s e fe a tu r e s can b e tr e a te d in a s im ila r w ay to
riparian zones. Identify areas with the best ericaceous
vegetation and wet flushes and design wide open areas
around them. Ride junctions can be im proved for black
grouse by felling trees back from each corner to create
open enclaves and respacing trees further back into the
cro p to c re a te a 'g ra d e d e d g e '. W id e rid e s can be
planted with a scattering or groups of larch and birch to
create spring forage. W ide rides can be used to 'link-up'
isolated patches of suitable black grouse habitat and act
as corridors dow n w hich hens w ith broods can m ove
and feed.
It is im portant that habitat m anipulations w ithin Black
G r o u s e M a n a g e m e n t A re a s a re d o c u m e n te d an d
progress review ed at least every 2 years. Fixed-point
p h o to g ra p h ic re c o r d s o f s ite s at v a rio u s sta g e s o f
m anagem ent will provide a useful, qualitative record of
habitat changes over time. In m ost forests it will not be
possible to m easu re d irectly the use of sites by black
grouse. The presence of fresh droppings are a useful
indicator that black grouse are present in an area and a
record of casu al sigh ting s of b ird s can be u sefu l too.
But, the long-term success of m anagem ent prescriptions
should be measured by increases in the density or range
of black grouse w ithin a geographical area. C ounts of
displaying m ales provide the easiest yard-stick against
which success can be m easured.
Clear felled and replanted sites
Sporting
F ellin g of m ature stan d s in trod u ces sp atial d iversity
into even -aged forests and creates open areas w hich
black grouse exploit. In m uch of W ales and Scotland,
extensive felling of post-w ar plantations has just started
and will increase dram atically in the 1990s and the next
cen tu ry . T h is w ill crea te m uch p o te n tia lly su ita b le
habitat for black grouse, and m ay well result in som e
populations increasing.
T h e b lack g ro u se is a gam e sp e c ie s, co v ered by the
G am e A cts w ith an open seaso n from 20 A u g u st-10
D e ce m b e r. S m a ll, fra g m e n te d p o p u la tio n s at low
density are the m ost vulnerable to the effects of hunting
and a voluntary m oritorium on shooting in such areas is
w ise , a t le a s t u n til p o p u la tio n s h a v e re c o v e re d to
som ething approaching their form er numbers.
Roads, rides and fire breaks
V ery little is know n about the su itab ility of clear
felled and replanted h abitats for black grouse, but so
long as heather regenerates in quantity, these areas will
provide ideal feeding conditions for adults for up to 1015 years before the tree canopy closes. No inform ation
exists on the optim um size of clear felled areas for black
grouse. In W ales black grouse used areas sm aller than
5 ha as well as larger areas, suggesting that size m ay be
unim portant. Deer often becam e established in forests
during the first rotation. O n restocked sites they m ay
preferentially graze m any of the food plants im portant
to black grouse.
The use of herbicides and insecticides m ay in time
be detrim ental to black grouse. M inim um use should be
m ade of broad-spectrum herbicides such as glyphosate
(Roundup) in restocked areas with vegetation suitable
fo r b la c k g ro u se b e c a u s e th is w ill re d u c e the food
supply and the availability of nest sites (Cayford, 1988).
Sim ilarly, insecticides should not be used on restocked
areas w ithin Black G rouse M anagem ent A reas during
the breeding season as this is likely to deplete the insect
food essential for chick survival. Treatm ent of young
planting stock against attack by H ylobius is unlikely to
cause problem s so long as insecticide is applied only to
the young trees.
It is im portant that all w et flushes, particularly those
w ith rushes and cotton grass, should not be replanted
ADDRESSES FOR ADVICE
Royal Society for the Protection of Birds, Conservation
M a n a g e m e n t A d v iso ry S e rv ic e , T h e L o d g e, S a n d y ,
Bedfordshire, SG 19 2DL.
Gam e Conservancy, Crubenim ore Lodge, N ew tonm ore,
Inverness-shire, PH 20 1BE.
T h e F o re stry A u th o rity , W ild life and C o n se rv a tio n
R e s e a r c h B r a n c h , A r d e n tin n y , D u n o o n , A r g y ll,
PA23 8TS.
ACKNOWLEDGEMENTS
The RSPB acknow ledges the generosity of the Forestry
C om m ission in funding their research w ork in W ales
and the co-operation of their staff, particularly A lastair
Sco tt, Fred C u rrie, Jo n W estlak e, M ark Y ork e, H ugh
C la y d en , P au l S h e rrin g to n , P h il R a tcliffe and C olin
B a n c r o ft. S te v e P e tty , W ild life an d C o n s e rv a tio n
R e s e a r c h B ra n c h (T h e F o r e s t r y A u th o r ity ) m a d e
num erous im provem ents to the text. Drs Colin Bibby,
N ick Picozzi and Peter H udson refereed an earlier draft
fo r w h ich th a n k s a re g iv en . P e te r H o p e Jo n e s , D r
Robert M oss, Dr Per Angelstam , Prof. David Jenkins, Dr
P eter G arson, A nne Starlin g and D r D avid Baines all
contributed to valuable discussions. D iane C hadw ick
p a t ie n t ly r e v is e d m a n y d r a fts a n d G e o r g e G a te
produced the figures.
10
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