NOTES FROM THE MAMMAL SOCIETY-NO. 42 279 Notes on the performance of Red deer, Cervus elaphus, in a woodland habitat BRIAN MITCHELL, Institute of Terrestrial Ecology, Banchory Research Station, Banchory, Kincardineshire, Scotland. WILLIAM GRANT, M.B.E. and JOHN CUBBY, Forestry Commission, Grizedale, Ambleside, Cumbria, England. This paper considers the body growth and reproductive features of Red deer (Cervus elaphus L.) in a woodland area of north-west England, with comments on the broad differences in performance between these deer and those on open hill-range in Scotland. The data summarised here were collected from 319 animals (85 stags, 134 hinds and 100 calves) shot at Grizedale Forest, Cunibria, from autumn 1969 to early winter 1977/78. Up to now, research on the population dynamics and performance of Red deer in Britain has been concentrated on deer on open hill-range in Scotland (e.g. Lowe, 1969, 1971 ; Mitchell, 1973; Mitchell, McCowan & Nicholson, 1976; Mitchell, Staines & Welch, 1977; Staines, 1978; Mitchell & Crisp, 1981). This is because most of Britain’s free- ranging Red deer occur at relatively high densities of population over large areas of this atypical habitat for the species, and where problems of land-use centred on the deer stimulated research relevant to deer control and cropping (see Red Deer Commission Annual Reports, 1961 onwards). Elsewhere in Britain, however, Red deer are widely distributed, though in smaller concentrations, in natural and man-made woodlands, and little has been published on the growth rates and reproductive potential of these deer. Such information would be useful for management purposes. Study urea and methods Grizedale Forest is at the southern edge of the Lake District, and consists of 3500 ha of rather hilly terrain (altitude range 100-300m). Much of the area is woodland, partly natural oak ( 350 ha), but mainly commercial plantings of conifers, and includes some unplanted clearings and 285 ha of low-lying farmland (mostly used for sheep and cattle). The whole Forest is owned by the Forestry Commission, and is bordered by other woodland and farmland. Red deer are indigenous to the Lake District, and although hybridisation with non-native Sika deer (Cervus nippon Temminck) has been detected in some parts of this region (Lowe & Gardiner, 1975, 1976), no obvious hybrids were found at Grizedale in our study period. Even so, the deer at Grizedale are not isolated, and there must be some interchange of deer between his and the surrounding area. The main aims of managing the Red deer at Grizedale are to conserve a stock of native deer, but also to minimise damage by deer to the trees; this necessitates deer control by culling, as well as tree protection by deer fencing. The plan is to maintain a post-winter stock of about 140 Red deer (as counted), and the numbers are checked twice a year (Grant, 1976). Because of difficulties in counting deer in woodland conditions, the real numbers are probably a little higher than the counts suggest. The deer are shot within the statutory open seasons for Red deer in England (Deer Act, 1963), adult stags being taken mostly in October, and hinds, calves and young stags from November to February. After shooting, each deer is weighed first as a “larder carcass” (complete animal less blood and alimentary tract), and finally as a “skinned fully-dressed carcass” (larder carcass less “pluck”, kidneys, genitals, udder, skin, head and feet). For research purposes, jaw-bones, re- productive organs (testes from stags, and uteri with contents and ovaries from hinds), and
Transcript
NOTES FROM T H E M A M M A L SOCIETY-NO. 42 279
Notes on the performance of Red deer, Cervus elaphus, in a woodland habitat
BRIAN MITCHELL, Institute of Terrestrial Ecology, Banchory Research Station, Banchory, Kincardineshire, Scotland.
WILLIAM GRANT, M.B.E. and JOHN CUBBY, Forestry Commission, Grizedale, Ambleside, Cumbria, England.
This paper considers the body growth and reproductive features of Red deer (Cervus elaphus L.) in a woodland area of north-west England, with comments on the broad differences in performance between these deer and those on open hill-range in Scotland. The data summarised here were collected from 319 animals (85 stags, 134 hinds and 100 calves) shot a t Grizedale Forest, Cunibria, from autumn 1969 to early winter 1977/78.
Up to now, research on the population dynamics and performance of Red deer in Britain has been concentrated on deer on open hill-range in Scotland (e.g. Lowe, 1969, 1971 ; Mitchell, 1973; Mitchell, McCowan & Nicholson, 1976; Mitchell, Staines & Welch, 1977; Staines, 1978; Mitchell & Crisp, 1981). This is because most of Britain’s free- ranging Red deer occur a t relatively high densities of population over large areas of this atypical habitat for the species, and where problems of land-use centred on the deer stimulated research relevant to deer control and cropping (see Red Deer Commission Annual Reports, 1961 onwards). Elsewhere in Britain, however, Red deer are widely distributed, though in smaller concentrations, in natural and man-made woodlands, and little has been published on the growth rates and reproductive potential of these deer. Such information would be useful for management purposes.
Study urea and methods
Grizedale Forest is at the southern edge of the Lake District, and consists of 3500 ha of rather hilly terrain (altitude range 100-300m). Much of the area is woodland, partly natural oak ( 350 ha), but mainly commercial plantings of conifers, and includes some unplanted clearings and 285 ha of low-lying farmland (mostly used for sheep and cattle). The whole Forest is owned by the Forestry Commission, and is bordered by other woodland and farmland.
Red deer are indigenous to the Lake District, and although hybridisation with non-native Sika deer (Cervus nippon Temminck) has been detected in some parts of this region (Lowe & Gardiner, 1975, 1976), no obvious hybrids were found at Grizedale in our study period. Even so, the deer at Grizedale are not isolated, and there must be some interchange of deer between his and the surrounding area. The main aims of managing the Red deer at Grizedale are to conserve a stock of native deer, but also to minimise damage by deer to the trees; this necessitates deer control by culling, as well as tree protection by deer fencing. The plan is to maintain a post-winter stock of about 140 Red deer (as counted), and the numbers are checked twice a year (Grant, 1976). Because of difficulties in counting deer in woodland conditions, the real numbers are probably a little higher than the counts suggest.
The deer are shot within the statutory open seasons for Red deer in England (Deer Act, 1963), adult stags being taken mostly in October, and hinds, calves and young stags from November to February. After shooting, each deer is weighed first as a “larder carcass” (complete animal less blood and alimentary tract), and finally as a “skinned fully-dressed carcass” (larder carcass less “pluck”, kidneys, genitals, udder, skin, head and feet). For research purposes, jaw-bones, re- productive organs (testes from stags, and uteri with contents and ovaries from hinds), and
280
udders (from hinds) were collected, preserved and labelled individually. Additional study material gathered together included pairs of antlers (cut off at the pedicels) from yearling (14 years-old) and fully grown adult (5 to 10 years-old) stags; these were not individually labelled, but were weighed as pairs.
Ages of shot deer were assessed using a combination of dental cement sectioning (Mitchell, 1967) and tooth replacement and wear criteria (Mitchell & Youngson, 1978). Jaw-bone length was measured as an index of skeletal size (Mitchell, McCowan PI al., 1976). Epididymal smears were examined for spermatozoa and stags were classed as “fertile” if spermatozoa were found. Hinds shot after 1 December (i.e. after the main period of rutting) were classed as “pregnant” if they showed large corpora lutea or other signs of pregnancy; in fact, hinds generally showed neither or both. Embryos were weighed as a means of estimating their approximate gestational age (Mitchell & Lincoln, 1973), and sexed if over 5 g. Udders were weighed, and then dissected to detect the presence of milk. All calves were checked carefully for any signs of unusually early sexual maturation.
Results Our data on body size and fertility in each age-class of stags and hinds are summarised
in Tables T and 11, giving standard deviations only where four or more individuals were
NOTES F R O M THE M A M M A L SOCIETY-No. 42
T A B L E I Features of stags shot in autumn (1969-1977)
Age classes C 1 2 3 4 5 6 7 8 9 10 11 12 5-10 Total
Numbers (n) Jaw length mean
(mm) ~ s . D . Larder weight mean
(kg) ~ s . D . Dressed mean weight (kg) + S.D.
Fertility (% with sperms)
48 61 10 3 185 225 241 247
9.5 10.3 7.7 - 37 59 76 88 6.9 9.4 11.5 -
26 41 51 59 5.1 7.1 8.9 - 0 85.7 100 100
2 265
111
75
100
-
-
1 279
145
107
100
-
-
-
1 2 279 271
142 138
100 92
100 100
_ -
- _
1 1 265 275 _ - 130 166
89 116
100 100
_ -
_ -
1 -
-
140
93
100
_
-
1 -
-
151
104 -
_
7 133 274
5.9 144 15.2 99 12.8
100
TABLE I 1 Fenfures of hinds shot in nutrrmtc-earfy winter (1969/70-1977/78)
measured. Age-classes are given to the nearest completed year, and calves are shown as “c”. For comparative purposes, we give both kinds of carcass weight and the features of deer aged 5-10 years, i.e. the age-range of maximum body size.
Because of the difficulties of shooting deer in a concealing habitat, where the groups of deer tend to be small and their behaviour secretive, the shooting at Grizedale was un- doubtedly much less selective (as a sampling process) than that done on open hill-range in Scotland (Mitchell, Staines el al., 1977 ; and personal observations). Consequently, our data may have little sampling bias, thus reflecting the real changes with age in stags and hinds, as well as giving useful indications of the age structures of stags and hinds in the live population (discussed further below). The age frequencies of shot stags and hinds suggest this, though admittedly yearling stags seem a little over-represented.
In body weight and skeletal size, the deer at Grizedale were much larger than those on Scottish hill-range (data sources referred to earlier), with higher rates of early growth and greater sizes attained as adults. Adult stags, for example, were 67 :( heavier, and hinds 34 % heavier, than on the Isle of Rhum (a fairly typical hill-range population), with correspond- ing differences of 73 % and 38 % between Grizedale and Glen Feshie (one of the poorer populations in Scotland). Nonetheless, the patterns of growth were similar, with no indica- tions that faster growth led to earlier attainment of maximum body size. Adult stags and hinds at Grizedale also differed to a much greater extent (ie. stags 2.1 times as heavy as hinds) than on Scottish hill-range (i.e. stags 1 a7 times as heavy a shinds). This suggests that conditions favouring better growth jn stags lead to higher reproductive output in hinds (see below) but only partly at the expense of increased body growth.
The first sets of antlers on Red deer stags (i.e. on yearlings) tend to be simple unbranched spikes, although the poorest yearlings may develop little more than fur covered knobs. On Scottish hill-range, “knobbers” can be almost as common as “spikers” amongst yearlings and the weight of dry antler material ranges from about 5 to 50g, with an average of about 25 gm per set. Most of the yearlings observed at Grizedale were “spikers”, with appreciably larger antlers, the available sample (n = 7 sets) giving an average weight of 101 g (s.D. k 21) per set. The branched antler sets on fully grown Scottish stags (5 to 10 years-old) varied from about 1200 to 1400 g (population averages), whereas at Grizedale they were about twice as heavy (mean = 2730 g, S.D. = f 380, n = 24 sets).
Although we found no sexually mature calves of either sex and no lactating yearling hinds, at Grizedale, the hinds clearly showed a higher reproductive potential than those on Scottish hill-range. At least 65 % of the yearling hinds were fertile (pregnant) and only one older hind (1 %) was not. Most Scottish hinds attain puberty a year later (as 2 year-olds), except in areas of unusually low population density where some become mature as yearlings. Appreciable proportions of hinds on Scottish hill-range also fail to ovulate and conceive when supporting calves (i.e. typically around 50 % in high-density populations) and adult hinds are classified as either “milk” (supporting calves) or “yeld” (without calves). In late autumn, just after the rutting period, milk hinds are usually in poor condition and with a low pregnancy rate. whilst yeld hinds are in good condition and with a high pregnancy rate. Therefore, appreciable proportions of these hinds fail to breed in successive years, quite unlike those at Grizedale which tend to breed every year once mature. In fact, only two (2%) yeld (non-lactating) individuals were found amongst the adult hinds shot at Grizedale before the end of December (lactation discussed further below) and although pregnant these animals were both well below average in body weight and jaw-bone length.
282
From the data, we could expect a birth-rate at Grizedale of about 70 calves per 100 hinds compared to about 4046 calves per 100 hinds on Scottish hill-range. Counts done in autumn at Grizedale (1973-1978) supported this, showing an average of 44.8 calves and 69 hinds, i.e. indicating a birth-rate of at least 65 calves/100 hinds.
As would be expected from their higher reproductive potential, the deer at Grizedale apparently had a much younger mean age than those on Scottish hill-range. The shooting data suggest that only 11 % of the Grizedale deer were older than 5 years compared to about 30 % at Glen Feshie and Rhum.
Although no multiple pregnancies were found at Grizedale in our study period, one example with twin embryos (male and female, both well developed) was reported later (P. Ratcliffe, personal communication). In all, this amounts to one case in a total of about 140 pregnant hinds examined, suggesting a higher frequency of twinning than on Scottish hill-range, i.e. less than 1/600 (Mitchell, 1973).
It is well known that lactation is prolonged in Red deer (Arman, Kay, Goodall & Sharman, 1974) and that it varies considerably amongst hinds (Mitchell, McCowan et al., 1976) ; some individuals apparently continue to lactate from one parturition through to the next although the rate clearly declines during the winter. At Grizedale, udders declined in weight over the autumn, indicating a progressive decline in the rate of lactation but with a sharp increase in the proportion of dry udders beyond December (Table 111). Even so, a few hinds were still producing milk in February, i.e. nine months after parturition.
NOTES FROM THE M A M M A L SOCIETY-No. 42
TABLE 111
Some changes in riiature hinds during the shooting season
Months Nov Dec Jan Feb
Numbers of hinds ( 3 4 years) 12 9 23 10 Mean dressed carcase weight (kg)? S.D. 51 f 5.3 46 f 5.8 45 f 4.8 46 f 4.8 Mean udder weight (gm) & S.D. 690 t 32 561 f 24 205 f 94 143 f 24 Proportion lactating (%) 100 100 40 20
Approximate dates of conception and birth (Fig. I), estimated from embryo weights and dates of shooting (method and assumptions in Mitchell & Lincoln, 1973), indicated that these were spread over periods of about 90 days, with a sharp peak of conceptions in mid October and one of births in early June. In both timing and duration, these results agree well with those found in Scotland and elsewhere (Fletcher, 1974; Guinness, Gibson & Clutton-Brock, 1978). These results also suggest that yearling hinds (i.e. first breeders) tended to breed a little later on average than older hinds.
Due to the small samples obtained, our data on the sex-ratios of embryos (sexable embryos = 23 males : 18 females) and shot calves (48 stag calves : 52 hind calves) gave no indications as to whether there was likely to be an excess of either sex amongst recruits into the population. Deer older than calves were, of course, easy to sex by observation and target numbers of stags and hinds were specified before each annual cull. Therefore, the actual sex-ratio of adult deer in the Grizedale area must be largely determined by local shooting practices.
NOTES F R O M T H E MAMMAL SOCIETY--No. 4 2 283
It remains to be shown whether the deer at Grizedale are typical in performance of Red deer in other woodland habitats in Britain, or whether there is considerable variability. Apart from the management value of this kind of information, it would be interesting to know, for example, the maximum growth characteristics for stags and hinds in these habitats, whether or not pregnancy rates of 100% in yearlings and older hinds are ever attained in the wild and if multiple pregnancies are reasonably frequent in any of these populations.
25
20
15
t s n z
10
llll - 112 119 216 b ; 116 $3 40 ; Id 21 20 4 I1 -
I I I
- I
- - - + - - - -
-
7 - - -
-
- Adult hinds
-
FIG. 1 . Approximate periods of conception and parturition.
REFERENCES
Arman, P., Kay, R. N. B., Goodall, E. D. & Sharman, G. A. M. (1974). The composition and yield of milk from
Fletcher, T. J. (1974). The timing of reproduction in Red deer (Cervus elaphus) in relation to latitude. J. Zool.,
Grant, W. (1976). Management of Red deer at Grizedale Forest. Deer 4: 33-37. Guiness, F. E., Gibson, R. M. & Clutton-Brock, T. H. (1978). Calving times of Red deer (Cervus elaphus) on Rhum.
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284 NOTES F R O M T H E M A M M A L SOCIETY-No. 42
Lowe, V. P. W. & Gardiner, A. S. (1975). Hybridisation between Red deer (Cervus eluphus) and Sika deer (Cervus
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Behaviour of badgers (Meles rneles) infected with bovine tuberculosis
C. L. CHEESEMAN and P. J. MALLINSON, Ministry of Agriculture, Fisheries and Food, Agricultural Science Service, Worplesdon Laboratory, Tangley Place, Worplesdon, Guildford, Surrey.
Bovine tuberculosis (Mycobacteriurn bovis) is a major cause of natural death in badgers in Gloucestershire (Gallagher & Nelson, 1979). Behavioural changes in ailing badgers have been reported (Muirhead et al., 1974) including being seen abroad during daylight, sometimes in or around farm buildings, with no fear of man. This note reports the beha- viour of three badgers, which post-mortem examination showed were infected with bovine tuberculosis. They were observed in an area of the Gloucestershire Cotswold escarpment where badger ecology and behaviour are being studied. Movements were observed by radio tracking (Cheeseman & Mallinson, 1979) and post-mortem examinations were carried out at the Ministry’s Veterinary Investigation Centre at Gloucester.
Case 1 Sow G7. This badger was caught 3 May 1977 whilst foraging for earthworms in short
grass pasture. Its gait was contorted and its back hunched and at 6-0 kg it appeared to be underweight for an adult female. Its original social group was not known. A transmitter was fitted and on release it went to ground nearby in a small, unoccupied outlying sett which was close to a territorial boundary between two social groups of badgers.
Subsequently on nine consecutive nights the badger was observed foraging within 150 m radius of the sett, mostly in short grass pasture where earthworms were abundantly
