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Impact of muntjac deer (Muntiacus
reevesi) at Monks Wood National
Nature Reserve, Cambridgeshire,
eastern England
A.S. COOKE1 AND L. FARRELL2
1 13
Biggin Lane, Ramsey, Huntingdon, Cambridgeshire PE26 1NB, England
Natural Heritage, 1 Kilmory Estate, Kilmory, Lochgilphead, Argyll PA31 9RR, Scotland
2 Scottish
Summary
Muntjac deer (Muntiacus reevesi) were first reported at Monks Wood National Nature Reserve,
Cambridgeshire, in the early 1970s. By 1985, they had had noticeable effects on coppice regrowth,
principally of hazel (Corylus avellana), field maple (Acer campestre) and ash (Fraxinus excelsior).
Despite trials of various protective measures, coppicing operations were suspended in the wood in
1995 because of browsing impact. Other woody vegetation had been heavily browsed and for some
species abundance had been affected, e.g. bramble (Rubus fruticosus). Among the ground flora there
have been effects on the vigour, reproduction and abundance of a range of common and rare species.
Other plant species, such as some grasses and sedges, have increased because they are avoided by
deer, are more tolerant of grazing or have benefited from changes in management. Invertebrates, in
particular, may have been affected by these changes in plant composition with, for instance,
increases being noted for lepidopteran species dependent on grasses.
Introduction
Monks Wood is the largest wood in Cambridgeshire, extending to 157 ha. For centuries it
had been managed traditionally as coppice-withstandards, but much of it was clear-felled at the
end of the First World War (Steele and Welch,
1973; Massey and Welch, 1994). In 1953/54 it
was purchased by the then Nature Conservancy
(now English Nature) and established as a
National Nature Reserve. The forest canopy is
predominantly ash (Fraxinus excelsior) with
pedunculate oak (Quercus robur); the shrub zone
© Institute of Chartered Foresters, 2001
is diverse and includes hazel (Corylus avellana)
and field maple (Acer campestre). Structural and
habitat variety is enhanced by ponds, streams,
rides and areas of grassland, and the wood supports rich assemblages of ground flora and invertebrates (Massey and Welch, 1994). It is classified
as Fraxinus excelsior–Acer campestre–Mercurialis
perennis woodland, community W8 (Rodwell,
1991).
Monks Wood has the largest and densest population of muntjac (Muntiacus reevesi) so far documented in Britain (Cooke et al., 1996). Reasons
for this situation include that the reserve is in a
Forestry, Vol. 74, No. 3, 2001
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F O R E S T RY
region that has been colonized by muntjac for
many decades (Chapman et al., 1994), and until
recently the deer population was not culled inside
the wood. Large woods may also tend to have
more extensive quiet areas compared with small
woods, and therefore contain disproportionately
high numbers of deer (Cooke, 1996; van Gaasbeek et al., 2000).
By the mid-1980s, it became apparent to the
woodland managers that deer were having
unacceptable effects on coppice. Trials were initiated, first protecting cut stumps with brash, then
fencing whole coppice coupes (Cooke, 1994a;
Cooke and Lakhani, 1996). Further studies
demonstrated that effects were not restricted to
coppice, but extended more widely in the wood
and to other organisms e.g. ground flora and
invertebrates (Pollard and Cooke, 1994; Wells,
1994; Cooke et al., 1995; Cooke, 1997). Concerns raised by this work resulted in English
Nature liaising with stalkers shooting outside the
wood from the mid-1990s, then permitting
shooting within the wood from 1998. The work
has also helped to raise awareness of the effects
of muntjac in woodlands, and has led to monitoring and management elsewhere (Cooke, 1996,
2001).
This paper is a descriptive account of changes
and effects in Monks Wood, drawing on published work and previously unpublished observations on coppice regrowth, semi-natural woody
vegetation, ground vegetation and other fauna. It
begins with a brief account of trends in the
muntjac population.
Deer population trends
From initial records in ~1970, numbers of
muntjac increased until 1985 (Cooke, 1994a).
Mean numbers counted per hour, based on 6–14
surveillance walks each January–May, 1986–
2000, are summarized in Figure 1. On average
~20 muntjac per hour could be seen up to 1998.
In a separate investigation, counts in 1 ha plots
along a transect in the summer of 1993 suggested
a density of ~1.2 ha–1 (equivalent to a total population of ~190 muntjac; Cooke et al., 1996).
Recent shooting within the wood has led to a
decline in deer numbers. During 1998/99, 106
were shot inside and just outside the wood (P.
Figure 1. Mean number of muntjac seen in Monks
Wood during dusk walks, January–May 1986–2000.
Green, personal communication); other muntjac
have also been shot by stalkers not reporting back
to English Nature. The effect of this cull was to
reduce mean numbers seen from 17 per hour in
1998 to 6 per hour in 1999 (t18 = 4.96, P < 0.001;
Figure 1). Using the mark-resighting technique
described by Mayle et al. (1999) in a study area
of 61 ha in the south of the wood, density was
estimated to be 1.1 ha–1 in 1998 and 0.3–0.6 ha–1
in 1999.
Other mammalian grazers and browsers occur
and have also caused difficulties for the woodland managers, e.g. rabbits (Oryctolagus cuniculus) and brown hares (Lepus europaeus)
hindered attempts to re-establish hazel in
coppice areas (Massey, 1994a). In 1993/94,
numbers recorded during 96 walks along an
8 km fixed route may roughly reflect the relative
abundance of certain species: muntjac 2333,
Chinese water deer (Hydropotes inermis) 13, roe
deer (Capreolus capreolus) 2, rabbit 559 and
brown hare 384 (Cooke et al., 1995). Through
the late 1980s and early 1990s, muntjac will
have been the predominant grazers and browsers
listed above. The contribution from small
mammals should not, however, be ignored (e.g.
grazing on bluebells Hyacinthoides non-scripta;
Cooke, 1997).
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I M PA C T O F M U N T J A C D E E R AT M O N K S W O O D
Coppice regrowth
Until 1914, the wood was actively coppiced on a
20-year rotation, with the standards also being
harvested (Hooper, 1973). Since the 1950s,
12.7 ha distributed across 17 sub-compartments
have been returned to coppice on a rotation of
10 years, and the shrub zone beside major rides
has also been cut to diversify habitat (Massey,
1994a). From 1987, regrowth was protected
against browsing by muntjac, first by brash piles
on the stumps, then by electric fencing (Cooke,
1994a; Cooke and Lakhani, 1996). More
recently, rideside clearance has been protected
with metal, wire-mesh or plastic fencing.
Muntjac are small deer and mainly browse
regrowth stems up to a height of 100 cm (Cooke
and Farrell, 1995). Stems that are taller may be
bitten at a convenient height and broken so that
their tips can be defoliated (Cooke and Farrell,
1995). Although less commonly encountered
than direct browsing, breakage often causes loss
of leading regrowth stems. Stems are usually safe
from breakage once they have attained a thickness of 1 cm at a height of 1 m. It has been
observed that slow-growing species, e.g.
dogwood (Cornus sanguinea), are usually more
damaged by direct browsing during the first
growing season than species with rapid growth,
such as willow (Salix spp.; Cooke, 1994a). Similarly, slower-growing individuals of a single
species are more likely to be seriously damaged
(Cooke and Farrell, 1995).
Browsing of regrowth does not always lead to
significant ecological or conservation impact. At
the level of an individual stool, browsing may
have negligible effect on the final canopy after
regrowth, it may reduce the canopy density perceptibly (Cooke and Farrell, 1995), or, if all
regrowth is destroyed and browsing continues,
the stool is likely to die within a few years
(Cooke, 1998a). Depending on the conservation
objectives, reductions in canopy density at coupe
level may be unacceptable to managers because of
effects on vegetation succession.
Acceptability of browsing can be determined in
several ways such as by visual assessment (Cooke,
1994a) or by counting stems reaching canopy
height per unit area or per stool (Cooke and
Lakhani, 1996). The final decision involves a value
judgement, comparing aims and observations.
243
Visual assessment for the four principal coppice
coupes cut between 1985 and 1988 indicated
failure in 1985 and 1986 when they were unprotected against muntjac, but marginal acceptability
in 1987 and 1988 when brash piles were used,
although the high density of standard trees may
have caused shading problems (Cooke, 1994a;
Massey, 1994b). Counting canopy stems per unit
area in nine coupes that had been cut between
1989 and 1993 and protected with electric fences
revealed that two had failed, one was poor and
unacceptable, while six were acceptable.
However, one of the last group had suffered a
browsing-mediated shift in the composition of the
canopy towards birch (Betula spp.) and away
from hazel and ash (Cooke, 1994a; Cooke and
Lakhani, 1996). Damage had resulted because the
electric fences failed to prevent access by deer,
especially in quiet areas of the wood. In contrast,
if coupes were adjacent to major rides, then
damage was relatively slight.
Within fenced and unfenced study plots,
browsing was positively related to dung counts in
the summer months (Cooke and Lakhani, 1996).
Deer and dung counts were also related to one
another, and it was calculated that if the deer
population was reduced by 90 per cent then
coppice regrowth would not need fencing (Cooke
and Lakhani, 1996). Such action in isolation was
considered impractical. An alternative suggestion
by Putman (1996) was to erect a fence around the
main area of coppice (6.1 ha), where four of the
seven coupes had failed because of deer browsing,
the last being cut in 1994. In 1999, deer fencing
was erected around the perimeter of the main
coppice block, and a second fence was erected
around 10.6 ha in the south-west corner of the
wood, where three other coppice coupes
occurred. The effects of these fences are being
monitored.
Semi-natural woody vegetation
In contrast to coppice regrowth, which was
acknowledged as being damaged by deer as early
as 1985, relatively little was known until recently
about possible effects on semi-natural woody vegetation. Peterken (1994) resurveyed in 1992 part
of a transect previously recorded in 1985 and
noted that the most obvious change was the
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destruction of privet (Ligustrum vulgare) undergrowth and groups of ash regeneration. He commented that privet had exceeded 1.3 m in 1985,
but was <0.3 m in 1992 and heavily browsed.
Privet is slow-growing with thin stems, and is
readily browsed and broken by muntjac.
Crampton et al. (1998) compared the composition of Monks Wood in 1964–66 with that in
1996 by means of temporary sample plots across
the wood and from a single permanent plot (70
35 m). They noted that, although ash seedlings
<30 cm in height were present through much of
the wood in both 1966 and 1996, most of the
saplings showed signs of browsing by 1996.
Muntjac can reach to ~115 cm by standing on
their hind legs, although they may browse higher
trailing vegetation by pulling it down (Cooke and
Farrell, 1995). Browselines, usually between 90
and 100 cm, are a common feature in Monks
Wood. Often these have little consequence for the
shrubs, especially if they are much taller. Bramble
(Rubus fruticosus), however, grows to 1–2 m in
height and can be heavily browsed, particularly in
the summer and again in the autumn (Cooke,
1996). Thickets of bramble dominated significant
areas of the wood in the early 1970s (Steele and
Welch, 1973), but by 20 years later few patches
remained and these were suffering die-back.
Crampton et al. (1998) commented that their
bramble records in 1996 were all for very small
plants or seedlings. Bramble does, however, continue to dominate inside exclosures erected in the
wood in 1978 (Cooke et al., 1995), except for
those breached by deer in the late 1990s.
Amounts of bramble may be an important factor
limiting the carrying capacity of Monks Wood
and other local reserves for deer populations in
winter (e.g. Cooke, 1998b).
To help understand browsing effects on the
development of semi-natural woody vegetation,
an experiment was set up in 1993. Four pairs of
relatively open plots were selected in each of two
areas of recently cut coppice (compartment 27c
cut in 1992 and 19a cut in 1993). One of each
pair was chosen at random for erection of a 4 4 m fence, 1 m high to exclude deer, rabbits and
brown hares. The other plot in each pair was left
unfenced as a control, although both compartments (i.e. including all plots) were electrically
fenced for two growing seasons following
coppicing. Beginning in 1993, recording was
undertaken each May in sixteen 0.5 0.5 m
quadrats in the centre 2 2 m of each plot.
Recording concentrated on the presence and
height attained in each quadrat by bramble,
privet and honeysuckle (Lonicera periclymenum),
and on measuring the height of each individual of
the three other commonest tree or shrub species
in each compartment. Final routine observations
were made in 1997, by which time bramble
growth made recording very difficult in the fenced
plots.
By 1997, no tree or shrub species exceeded
20 cm in any control plot; in compartment 19a,
tree and shrub growth of >20 cm was recorded
inside two fences with a mean number of plants
(± SE ) per 2 2 m of 2.0 ± 1.7 (excluding
bramble, privet and honeysuckle); in 27c, all
fences had tree and shrub growth of >20 cm with
a mean number of plants of 4.5 ± 2.0 (significantly different from controls, Mann–Whitney
U4,4 = 0, P < 0.05). A check of the control plots
in 1998 showed that one out of eight had a single
hawthorn (Crataegus monogyna) >20 cm in the
centre 2 2 m. It seemed that such survival and
growth was not possible till coarse grasses provided sufficient protection from browsing.
In 1997, mean numbers of seedlings or frequency of bramble, privet and honeysuckle were
higher inside the fences in all cases except one.
However, only for hawthorn in 19a was the
difference significant (paired t3 = 5.00, P < 0.05).
Significantly better growth was found in fenced
plots for privet and bramble in compartment 27c
and for hawthorn, honeysuckle and bramble in
19a (Friedman’s test on mean height change per
annum, P < 0.05; see Figure 2 for a typical
example). Although there was little or no growth
in the control plots, these species continued to
grow throughout the experiment inside the
fences.
Ground vegetation
Species directly affected by grazing
Muntjac have ready access to ground vegetation
whereas they can only take woody vegetation that
is within their reach. They appear to relish certain
species of ground flora, but avoid others, so some
species are directly affected while others may
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I M PA C T O F M U N T J A C D E E R AT M O N K S W O O D
Figure 2. Mean height attained by bramble inside
four exclosures in compartment 19a (unshaded bars)
and in four unfenced control plots (shaded bars).
benefit indirectly. In some cases, the former
species have been relatively rarely eaten in the
past by wild mammals or livestock, and are intolerant of grazing.
It took several years before it was appreciated
that the ground flora was changing. Work on
lady’s smock (Cardamine pratensis) revealed an
increase in the level of grazed flowers from 1986
(Cooke, 1994a; Dempster, 1997). However,
changes in abundance of rare species (e.g. herb
Paris Paris quadrifolia, early purple orchid
Orchis mascula and greater butterfly orchid Plantanthera chlorantha) and widespread species (e.g.
primrose Primula vulgaris, violet Viola spp., bluebell and wood anemone Anemone nemorosa)
were reported at the Monks Wood Symposium in
1993 (Massey, 1994a; Wells, 1994). Deer grazing
was suggested as a probable cause, although
aerial enrichment with nitrogen compounds and
changes in management were also discussed. At
the same time, studies on the direct effects of
grazing on certain species were beginning (Cooke,
1994a), among them bluebell, dog’s mercury
(Mercurialis perennis) and lords and ladies (Arum
maculatum).
Grazing on bluebell inflorescences is readily
apparent each spring (Cooke, 1994a, 1997). In
addition, earlier grazing of leaves reduces vigour,
the plants having shorter leaves (Cooke, 1997)
and shorter inflorescences with fewer flowers (T.
Sparks, personal communication). Information
on changes in abundance is, however, conflicting
245
(Wells, 1994; Cooke, 1997; Crampton et al.,
1998).
Cooke (1997) observed that bluebells inside
the exclosures erected in 1993 had shown a
partial, but significant, recovery in leaf length by
1995. These bluebells did not recover further; in
1998 the leaves were intermediate in length
between controls outside the exclosures and
leaves in situations with little or no deer grazing.
While it is possible that plants may not recover
totally from such a change, in some years up to
30 per cent of the leaves inside the exclosures
were grazed, presumably by small mammals.
Since 1993/94, bluebells have been monitored
by means of fixed 0.5 m quadrats in several localities in the wood, including a dense stand in the
woodland compartment 27f (Figure 3). Total
numbers of inflorescences and numbers grazed
varied from year to year, but the latter was particularly low in 1999, associated with reduced
deer numbers (Figure 1). Leaf length recovered
significantly in 1999 (t18 = 2.39, P < 0.05).
Dog’s mercury is heavily grazed and, except in
exclosures, is reduced considerably in size
because of grazing (Cooke et al., 1995; T. Sparks,
personal communication). Unlike bluebells, there
is good evidence of a marked decline in abundance since the 1970s (Cooke et al., 1995 and
unpublished). Lords and ladies is toxic to stock,
but is also grazed by muntjac (Diaz and Burton,
1996). In Monks Wood, >50 per cent of inflorescences have been recorded as being grazed, there
has been a low ratio of seedlings to mature plants,
and reproduction has been affected as there is a
reduced chance of setting seed (Diaz and Burton,
1996).
That these three well-studied species have been
affected directly by muntjac is beyond reasonable
doubt, but other factors cannot be totally
ignored. Putman (1996) suggested that increased
competition from vigorous grasses and sedges
may exacerbate any loss from coppice areas.
While early losses in coppice areas may not be
associated with increased grass growth, an
example from compartment 27c is given in Figure
3 of a decline in bluebell inflorescences over a
period of several years; the coppice canopy was
patchy where the bluebells were recorded and
their decline may have been related to growth of
grasses and sedges, as well as to shading by the
canopy. This coppice coupe has had higher deer
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activity than the woodland area (27f), and this is
reflected in the higher levels of grazing damage
and consistently shorter leaves.
Cooke (1996, 1997, 2001) described a technique with ivy stems inserted into the ground to
measure feeding activity of muntjac. Ivy trials
have demonstrated a reduction in feeding activity
in Monks Wood following the cull in 1998/99 as
the browse level after one day dropped significantly from 82 per cent in 1997 to 25 per cent in
1999 (t8 = 2.57, P < 0.05), so providing further
confirmation of the recent improvement in the
wood.
Generally, muntjac are considered to cause
little damage to agricultural interests. They do,
however, forage outside the wood and there have
been several instances when crops close to the
reserve have been affected by grazing. The most
serious case occurred in the winter of 1997/98
through to the summer of 1998 on two fields to
the east. Crops of field beans were growing in
both fields, which have a combined area of ~29 ha
and a shared boundary of ~770 m with the wood.
A mown grass strip runs down the entire western
edge of the fields to provide the deer with an open
area to cross and to make it easier to shoot them.
The deer had eaten the shoots, leaves and pods,
and breakage was used to bring down growing
tips. Transects into the fields at 50 m intervals and
perpendicular to the wood boundary revealed
that plant height was affected in the northern field
to 70 m and in the southern field to 45 m. Pod
length and number of pods per plant were both
positively related to plant height (Spearman rank
correlation coefficient, n = 18, P < 0.05), so it may
be reasonable to assume that yield was reduced
along the field edges.
Species that have increased
Figure 3. Information on bluebells in woodland
(compartment 27f, shaded bars) and in a coppice
area (compartment 27c, unshaded bars) showing (a)
mean number of inflorescences per 0.5 m quadrat,
1993–1999, (b) mean number grazed per quadrat
and (c) mean leaf length, 1994–1999.
Other species may benefit because their unpalatability or tolerance of grazing gives them an advantage over grazing-sensitive species or allows them
to flourish in an enriched environment (e.g. see
Putman, 1998). While most seem to be grasses or
sedges, a few are dicotyledonous species e.g.
ground ivy (Glechoma hederacea; Cooke et al.,
1995; Crampton et al., 1998) and spurge laurel
(Daphne laureola; van Gaasbeek et al., 2000).
Ground ivy is toxic to livestock (Cooper and
Johnson, 1984), and has a smell which we regard
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as characteristic and strongly pungent. Muntjac
tend to avoid areas dominated by ground ivy.
Deer were counted in twenty 0.5 ha woodland
plots bordering rides, four times each month at
midday and four times at dusk from May 1993
to April 1994; ground ivy was the dominant
summer/autumn vegetation in 10 of the plots, but
not in the others. Significantly fewer deer were
recorded in the plots dominated by ground ivy
during July–August, both at midday and at dusk
(Poisson regression analysis, P < 0.001; see Figure
4 for dusk), September–October (dusk, P < 0.05)
and November–December (day, P < 0.01).
Density of other ground vegetation made no
difference to numbers of deer seen.
247
deer grazing is unclear. Dense stands of pendulous
sedge have quickly become established in wet
parts of the wood where coppicing has failed to
produce an adequate canopy because of deer
browsing. Inside the 1978 exclosures, which
contain a profusion of species that have declined
in grazed areas, the grasses are less abundant
(Cooke et al., 1995). Inside those exclosures
breached in the late 1990s, grasses have now
become dominant. Management on the rides or
in the fields, for instance, will also have been conducive to encouraging the spread of grasses
(Wells, 1994). Aerial enrichment of nitrogen compounds has not been studied in this locality, but
amounts deposited may benefit certain monocotyledonous species in particular (Wells, 1994;
Pollard et al., 1998).
Fauna
Figure 4. Cumulative number of muntjac counted at
dusk, May 1993–April 1994, in 10 woodland plots
dominated by ground ivy (shaded bars) and 10 plots
not dominated by ground ivy (unshaded). Significant
differences were noted for July–August (P < 0.001)
and for September–October (P < 0.05).
The following species of grasses and sedges
have been reported as increasing in the wood in
recent years: wood small-reed (Calamagrostis
epigejos), false-brome (Brachypodium sylvaticum), tufted hair-grass (Deschampsia cespitosa), rough meadow grass (Poa trivialis),
pendulous sedge (Carex pendula) and pale sedge
(Carex pallescens; Wells, 1994; Cooke et al.,
1995; Crampton et al., 1998; Pollard et al.,
1998). Increased abundance has been noted for
certain of these species in a range of habitats in
the wood: on rides, in the open fields, in failed
coppice and in the woodland blocks. The role of
If muntjac have an effect on other fauna, it will
be via changes to vegetation and habitat needed
as food, shelter, nest sites, etc. These effects are
not necessarily detrimental. The vegetation
changes described above were most marked for
coppice regrowth, ground vegetation and the
shrub layer. This section considers the implications for several species of conservation interest.
For some species, little or no change has been
noted in recent years, e.g. the crested newt (Triturus cristatus; Cooke, 1994b and unpublished)
and brown hare (unpublished). Chinese water
deer, however, were first confirmed in the wood
in the 1970s, but declined from the late 1980s
(Figure 5; mean number per hour tested against
year 1986–2000, Spearman rank correlation
coefficient = –0.85, n = 15, P < 0.01). This decline
occurred during the period when the muntjac
population was highest (Cooke, 1994a).
Decreases in water deer numbers have occurred
in other local reserves as muntjac populations
increased (Cooke, 1998b; Cooke and Farrell,
1995). Both species require bramble for autumn
and winter forage, but the bramble thickets in
Monks Wood have disappeared. Periodic die-offs
of muntjac in Monks Wood (Cooke et al., 1996)
suggest suboptimal amounts of food in winter,
and this may be the reason for the current rarity
of water deer.
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Figure 5. Mean number of Chinese water deer seen
in Monks Wood during dusk walks, January–May
1986–2000.
The nightingale (Luscinia megarhynchos) typically prefers dense vegetation to heights of 3 m,
and concern has been expressed that deer browsing of coppice regrowth or of the shrub layer can
render habitat unsuitable (e.g. Fuller et al., 1999;
Fuller, 2001). Unfortunately there is a recording
gap from 1982 to 1987 inclusive in the numbers
of singing males in Monks Wood. From the data
available and from the more complete records at
the nearby reserves at Woodwalton Fen and
Holme Fen, numbers probably reached a peak in
the mid-1980s. Numbers for comparable periods
are assembled in Table 1 for the three reserves. In
isolation, the data for Monks Wood suggest a
decline in nightingale numbers that may be
Table 1: Mean numbers (± SE) of singing male
nightingales in Monks Wood and two other National
Nature Reserves in Cambridgeshire in 1976–1981
when muntjac were colonizing and in 1988–1996
when they were established
Reserve
1976–1981
1988–1996
Monks Wood
Woodwalton Fen
Holme Fen
11.2 ± 1.6 (6)
26.7 ± 3.5 (6)
28.3 ± 0.9 (6)
7.0 ± 0.7 (9)*
14.5 ± 2.7 (8)*
12.1 ± 4.0 (9)**
Number of years covered is given in brackets.
*t test compared with the early period, P < 0.05; **P
< 0.01.
related to coppice and shrub layer browsing by
muntjac. However, when the data for the three
reserves are considered collectively, they are less
convincing. Nightingales seem to have shown
temporally similar changes in all three reserves,
indicating that common factors were operating,
but when the declines started in Holme Fen and
Woodwalton Fen in the late 1980s, muntjac were
still comparatively rare there. Monks Wood has
had the densest deer population and the most
marked effects on vegetation damage, yet the
decline in nightingales is marginally greater in the
other reserves. It is difficult to believe that the
more robust habitats of Woodwalton Fen were
being sufficiently damaged in the late 1980s to
produce such an effect. Nevertheless, the impact
on coppice regrowth and the shrub layer since the
mid-1980s cannot have been beneficial to nightingales in Monks Wood.
Invertebrates that are dependent on specific
plants would seem to be at particular risk. Deer
browsing on low shrubs, such as bramble, has
resulted in their loss, whereas browsing on
higher-growing species, e.g. honeysuckle, has
caused marked browselines. The white admiral
butterfly (Ladoga camilla) tends to lay its eggs
low down on honeysuckle, and Pollard and
Cooke (1994) showed that potential and actual
egg-laying sites had been lost by deer browsing.
The white admiral population declined in Monks
Wood, but the decline was no worse than elsewhere. Thus, although the butterfly’s behaviour
was affected, the deer had no additional adverse
effect on population level.
In view of the increase in grass species in the
wood, Pollard et al. (1998) examined whether
lepidopteran species dependent on grasses had
fared better. They found that four out of 18
species of butterfly had increased in Monks Wood
since the 1970s and all had grass-feeding larvae.
Three of these species, the large skipper
(Ochlodes venata), speckled wood (Pararge
aegeria) and ringlet (Aphantopus hyperantus),
increased significantly relative to other sites in
eastern England. The grass-feeding group of
moths had similarly fared better than other moth
species. As noted above, the role of deer grazing
on the spread of grasses in the wood requires
elucidation.
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I M PA C T O F M U N T J A C D E E R AT M O N K S W O O D
Future research and monitoring
Specific items of research that are needed include
studying the effects of aerial inputs of nitrogen
compounds and other factors on the spread of
monocotyledonous species in the wood; and the
status of small mammals and their role as grazers
and browsers. Monitoring of the deer and their
effects is essential as the population is controlled
and vegetation recovers within the large new
exclosures; for instance, will the flora recover
fully and what will happen to bramble in the presence of limited or no browsing?
It is to be hoped that managers of other woodlands will continue to learn from the case of
Monks Wood how to recognize problems associated with muntjac and what to do about them.
Many conservation woodlands require protection
of coppice to try to prevent unacceptable levels of
damage (Cooke, 1996; Putman, 1998). Coppice
in Monks Wood has been considerably affected,
apparently by a muntjac density of 1 ha–1 or
more. If muntjac density could ever be reduced to
~0.1 ha–1 then coppice in Monks Wood should
not require protection (Cooke and Lakhani,
1996). While densities above this level might be
associated with unacceptable damage to
regrowth, it does not necessarily follow that such
a statement could be applied to other woodland
situations, as damage might depend on factors
such as amounts and spatial arrangement of
coppice and alternative food resources. Cooke
(1996, 2001) has advocated the prior use of ivy
trials and ‘scoring’ to determine whether new
coppicing management in a wood might lead to
unacceptable impact.
Marked changes to ground flora are much less
commonly encountered than serious impacts on
coppice and seem to be confined to woods with
muntjac densities approaching those at Monks
Wood, but this requires further work. Harris et
al. (1995) suggested that 0.3 ha–1 is a typical
density of adult muntjac in prime habitat, i.e.
equivalent to ~0.45 deer ha–1 when juveniles and
immatures are included. While a density of this
magnitude is likely to cause concerns for the
survival of coppice regrowth, it may not be
associated with significant effects on flora.
Whether such a deer density might detrimentally
affect the shrub layer in a wood is not yet clear,
249
but examination of bramble for winter browselines or die-back should provide a clue.
Acknowledgements
We thank T. Sparks for statistical advice and the
Reserve staff for their help and interest.
References
Chapman, N., Harris, S. and Stanford, A. 1994 Reeves’
muntjac Muntiacus reevesi in Britain: their history,
spread and habitat selection, and the role of human
intervention in accelerating their dispersal. Mammal
Rev. 24, 113–160.
Cooke, A.S. 1994a Colonisation by muntjac deer
Muntiacus reevesi and their impact on vegetation. In
Monks Wood National Nature Reserve: The Experience of 40 Years 1953–93. M.E. Massey and R.C.
Welch (eds). English Nature, Peterborough, pp.
45–61.
Cooke, A.S. 1994b Fluctuations in night counts of
crested newts at eight breeding sites in Huntingdonshire 1986–1993. In Conservation and Management
of Great Crested Newts. A. Gent and R. Bray (eds).
English Nature, Peterborough, pp. 68–70.
Cooke, A.S. 1996 Conservation, muntjac deer and
woodland reserve management. J. Pract. Ecol.
Conserv. Spec. Pub. 1, 43–52.
Cooke, A.S. 1997 Effects of grazing by muntjac (Muntiacus reevesi) on bluebells (Hyacinthoides nonscripta) and a field technique for assessing feeding
activity. J. Zool. Lond. 242, 365–369.
Cooke, A.S. 1998a Survival and regrowth performance
of coppiced ash (Fraxinus excelsior) in relation to
browsing damage by muntjac deer (Muntiacus
reevesi). Q. J. For. 92, 286–290.
Cooke, A.S. 1998b Colonisation of Holme Fen
National Nature Reserve by Chinese water deer and
muntjac, 1976–1997. Deer 10, 414–416.
Cooke, A.S. 2001 Information on muntjac from studying ivy. Deer 11, 498–500.
Cooke, A.S. and Farrell, L. 1995 Establishment and
impact of muntjac (Muntiacus reevesi) on two
National Nature Reserves. In Muntjac Deer: Their
Biology, Impact and Management in Britain. B.A.
Mayle (ed.). Forestry Commission, Farnham and
British Deer Society, Trentham, 48–62.
Cooke, A.S. and Lakhani, K. 1996 Damage to coppice
regrowth by muntjac deer Muntiacus reevesi and protection with electric fencing. Biol. Conserv. 75,
231–238.
Cooke, A.S., Farrell, L., Kirby, K.J. and Thomas, R.C.
07 Cooke (jr/d)
29/6/01
250
8:58 am
Page 250
F O R E S T RY
1995 Changes in abundance and size of dog’s
mercury apparently associated with grazing by
muntjac. Deer 9, 429–433.
Cooke, A.S., Green, P. and Chapman, N.G. 1996 Mortality in a feral population of muntjac Muntiacus
reevesi in England. Acta Theriol. 41, 277–286.
Cooper, M.R. and Johnson, A.W. 1984 Poisonous
Plants in Britain and their Effects on Animals and
Man. MAFF Reference Book 161. HMSO, London.
Crampton, A.B., Stutter, O., Kirby, K.J. and Welch,
R.C. 1998 Changes in the composition of Monks
Wood National Nature Reserve (Cambridgeshire,
UK) 1964–1996. Arboricult. J. 22, 229–245.
Dempster, J.P. 1997 The role of larval food resources
and adult movement in the population dynamics of
the orange-tip butterfly (Anthocaris cardamines).
Oecologia 111, 549–556.
Diaz, A. and Burton, R.J. 1996 Muntjac and lords and
ladies. Deer 10, 14–19.
Fuller, R.J. 2001 Responses of woodland birds to
increasing numbers of deer: a review of evidence and
mechanisms. Forestry 74, 289–298.
Fuller, R.J., Henderson, A.C.B. and Wilson, A.M. 1999
The nightingale in England – problems and
prospects. Br. Wildl. 10, 221–230.
Harris, S., Morris, P., Wray, S. and Yalden, D. 1995 A
Review of British Mammals. JNCC, Peterborough.
Hooper, M.D. 1973 History. In Monks Wood: A Nature
Reserve Record. R.C. Steele and R.C. Welch (eds).
Nature Conservancy, Huntingdon, pp. 22–35.
Massey, M.E. 1994a Managed change. In Monks Wood
National Nature Reserve: The Experience of 40
Years 1953–93. M.E. Massey and R.C. Welch (eds).
English Nature, Peterborough, pp. 13–17.
Massey, M.E. 1994b Changes in management policies.
In Monks Wood National Nature Reserve: The
Experience of 40 Years 1953–93. M.E. Massey and
R.C. Welch (eds). English Nature, Peterborough,
pp. 69–73.
Massey, M.E. and Welch, R.C. (eds) 1994 Monks Wood
National Nature Reserve: The Experience of 40
Years 1953–93. English Nature, Peterborough.
Mayle, B.A., Peace, A.J. and Gill, R.M.A. 1999 How
Many Deer? Forestry Commission, Edinburgh.
Peterken, G.F. 1994 Natural change in unmanaged
stands within Monks Wood NNR. In Monks Wood
National Nature Reserve: The Experience of 40
Years 1953–93. M.E. Massey and R.C. Welch (eds).
English Nature, Peterborough, pp. 1–8.
Pollard, E. and Cooke, A.S. 1994 Impact of muntjac
deer Muntiacus reevesi on egg-laying sites of the
white admiral butterfly Ladoga camilla in a Cambridgeshire wood. Biol. Conserv. 70, 189–191.
Pollard, E., Woiwod, I.P., Greatorex-Davies, J.N., Yates,
T.J. and Welch, R.C. 1998 The spread of coarse
grasses and changes in numbers of Lepidoptera in a
woodland nature reserve. Biol. Conserv. 84, 17–24.
Putman, R.J. 1996 Deer Management on National
Nature Reserves: Problems and Practices. Research
Report 173. English Nature, Peterborough.
Putman, R.J. 1998 Deer impact on conservation vegetation in England and Wales. In Population Ecology,
Management and Welfare of Deer. C.R. Goldspink,
S. King and R.J. Putman (eds). Manchester Metropolitan University, Manchester, pp. 61–66.
Rodwell, J.S. (ed.) 1991 British Plant Communities: 1
Woodland and Scrub. Cambridge University Press,
Cambridge.
Steele, R.C. and Welch, R.C. (eds) 1973 Monks Wood:
A Nature Reserve Record. Nature Conservancy,
Huntingdon.
van Gaasbeek, F., Waasdorp, D. and Sparks T. 2000
The status of Primula and Daphne laureola in Monks
Wood NNR in 1999. Huntingdon Fauna Flora Soc.
Rep. 1999 52, 8–12.
Wells, T.C.E. 1994 Changes in vegetation and flora. In
Monks Wood National Nature Reserve: The Experience of 40 Years 1953–93. M.E. Massey and R.C.
Welch (eds). English Nature, Peterborough, pp.
19–28.