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In order to evaluate the success of a population of red-legged partridges Alectoris rufa reintroduced into a 33.7 km2 study area, we estimated 15 demographic parameters from 1996 to 1999 by regularly monitoring the population through winter, spring and summer mapping censuses. During the study period, late winter population and spring dispersal decreased, pair number, brood number, brood production rate, chick survival and over winter losses were stable, whereas average brood size, juvenile number, age ratio, adult spring to summer survival, late summer population, and population growth rate from spring to late summer all increased. The population showed a moderate improvement in the overall productivity, mainly related to increased production of young and to a decrease in adult mortality. The improvement in breeding performance took place, in particular, after the second year of study with the conclusion of the releasing session of reared birds.
Radio transmitters were implanted intraperitoneally in 22 (nine females, 13 males) adult, territorial Eurasian beavers Castor fiber under field conditions. Two different injectable anaesthestic drug combinations were tested. Access to the peritoneal cavity was made through a ventral midline incision. The animals in group # 1 (N = 10) were initially injected with medetomidine (0.05 mg/kg), ketamine (5 mg/kg) and butorphanol (0.1 mg/kg). Three animals needed additional injections of the drug combination. Muscle relaxation was poor and variable and some of the animals were sound sensitive. When midazolam (0.25 mg/kg) was added to the drug combination (group # 2), muscle relaxation was excellent and the beavers (N = 12) did not react to sound stimuli. All surgeries were successfully performed. One animal in group # 1 died postoperatively due to circulatory failure. The behaviour and movements of the beavers did not appear to be affected by the procedure or the implant, except for the first few days when more time was spent inside the lodges. All beavers stayed in their original territory until they died, or as long as 17–24 months after the implantation. Based on these results, it appears that an injectable drug combination based on medetomidine, ketamine, butorphanol and midazolam and a surgical access through the ventral midline is suitable for implanting radio transmitters intraperitoneally in beavers under field conditions.
Sex, age, bone marrow fat (BMF) content, degree of carcass utilisation and terrain features were analysed for 118 ungulates killed by wolves Canis lupus in the Bieszczady Mountains, Poland, during the winters of 1992–1995 to assess the influence of snow depth on the wolves' predation patterns. In Bieszczady, the snow conditions during the study period were milder than average, with an average total annual snow depth of 1,372 cm and an average snow cover lasting for 94 days. Red deer Cervus elaphus were the primary wolf prey (81%), whereas wild boar Sus scrofa and roe deer Capreolus capreolus were killed less often (9% and 10%, respectively). The majority of prey (74%) was killed in creeks and ravines. The carcass exploitation by wolves was high; of the recovered prey, 55% was more than 60% consumed. The average condition of red deer, as based on BMF, was high (83.4%). BMF varied most among red deer stags and calves, and varied with annual snow depth (N = 29, P < 0.0 1; N = 28, P = 0.09) and monthly mean snow depth (τ = -0.37, P < 0.005; τ = -0.25, P = 0.06). Wolves killed adult red deer in creeks and ravines with the same frequency regardless of snow depth, whereas calves were killed less often in these places than should be expected from their overall proportion in the sample (N = 95, χ2 = 24.34, P < 0.001). During periods with thinner snow cover, consumption of red deer carcasses was slightly higher than during periods in which the snow cover was deep (τ = -0.42, P < 0.045).
Genetic variability and population structure was investigated in 83 European polecats Mustela putorius by means of six microsatellite markers. The samples came from two areas in Denmark, Østjylland and Thy, which are separated by the Limfjord. The genetic diversity (He = 0.583) found in the total sample was similar to those found in other mustelid species and carnivores in general. A heterozygote deficiency, probably due to a Wahlund effect, suggested a further substructuring of the Danish sample. Population genetic substructuring was investigated in three different ways: by means of the program STRUCTURE, Wright's F-statistics and by an assignment test. All the tests indicate a subdivision of the sample into two distinct groups, which is concordant with the two sampling locations, with an average genetic divergence of FST = 0.126 and RST = 0.1692. The higher genetic diversity found in the Thy population (He = 0.578), as compared to the Østjylland population (He = 0.420), could be explained by assuming two ancient waves of colonisation of the Danish peninsula. Tests for recent bottlenecks were conducted, and the results suggest no evidence of neither population decline nor expansion. Our study is the first one in which microsatellite markers are used on polecat samples, and one locus (mv54) was found to be diagnostic in distinguishing between American mink Mustela vison and European polecat.
Flight distances in roe deer Capreolus capreolus and fallow deer Dama dama with respect to a human observer on foot were measured in four nature reserves in the Netherlands: two dune reserves in the western part (the Amsterdam Water Supply Dunes (AWD) and Kennemerduinen (KD)) and two forested areas in the eastern part of the country (Hoge Veluwe (HV) and Kootwijk (KO)). In the four areas there is a gradient in hunting pressure from almost none in the AWD, via an increase in KD, to KO and HV. Fallow deer occur in both of the dune reserves and are not hunted. Of all the factors studied, hunting regime and habitat structure were most strongly related to flight distance. Although the number of individuals per group and most weather conditions also showed some relation to flight distances, their influence was relatively unimportant compared to that of hunting regime and habitat structure. When walking down wind, deer (both roe and fallow deer) flee at longer distances (64.7 ± 5.8 m) than when walking upwind (41.7 ± 3.3 m) or in calm wind (44.2 ±1.8 m). In the roe deer population of the AWD, flight distances were the shortest among all the studied areas. In both of the dune areas, the flight distances in dense vegetation structures were shorter than in open field. Fallow deer flight distances did not differ between the dune reserves AWD and KD.
By micro-histological analysis of plant remains in faecal pellets, we studied the diet of red deer Cervus elaphus during a summer season in the subalpine zone of the Swiss National Park in the eastern Swiss Alps. Hitherto, very little quantitative information on the diet of Alpine red deer populations has been published. Faecal species composition was found to conform to the general pattern known from elsewhere: it was dominated by graminoids with dwarf shrubs (mainly Erica camea) as a strong secondary component and forbs and coniferous browse in minor proportions. Practically all pellet samples contained food obtained both from pastures and forests, irrespectively of where the pellets were collected. Although forest plants contributed 28% of the fragment numbers and 41% of the fragment area in the pellets, coniferous tree browse accounted for only 2.5 and 5.0%, respectively. This supports the findings of other studies that red deer most likely has little impact on the forest dynamics in the Park. The spatial uniformity of faeces composition did not reflect the substantial differences in grassland vegetation between three study areas, probably because deer locally selected nutritious graminoids (particularly red fescue Festuca rubra) at patch level.
In most of Fennoscandia, moose Alces alces is intensively managed by the use of age and sex specific harvesting. This includes strong male biased harvesting, which over the last decade has resulted in a change in the sex and age composition of the populations. During the same period of time, a reduction in the proportion of male calves in the harvest has occurred all over Norway, probably reflecting a change in the secondary sex ratio. In order to examine for any causal link between these two patterns, we manipulated the structural composition of an isolated island population of moose in northern Norway and at the same time closely monitored the variation in the secondary sex ratio. In the first stage of the project, which was assumed to represent the conditions in a natural, unhunted moose population, the proportion of male calves increased significantly with the age of their fathers. Potentially, as a consequence of the high mean adult male age in the population, the secondary sex ratio was highly male biased. When we altered the male segment of the population, leaving only young (≤ 2½ years old) males as potential mates for the females, a significant increase in the proportion of female calves occurred in the population. Finally, in the last 3-years stage of the project, we reduced the adult sex ratio in the population to about 23% males and kept the adult male age relatively high. This again led to an increasing secondary sex ratio. These results suggest that the age composition of males in the population may affect the secondary sex ratio. The general significance of these results was supported by a larger temporal decrease in the proportion of males that were shot in the areas of Norway with larger changes in the sex composition of the hunting quotas than in the regions in which a less extreme harvest strategy were practised.
We studied Alaskan moose Alces alces gigas to test the hypothesis that sexual segregation among polygynous ruminants is the result of competitive exclusion of males by females. We first examined differences in foraging behaviour between sexes, and then tested whether foraging by females influenced subsequent browsing by males, an outcome necessary to postulate competitive exclusion of males by females. Our experiments during the winter of 1999 and 2000 were made on captive moose at the Kenai Moose Research Center, Alaska, USA. Twig diameters of Barclay willows Salix barclayi affected bite sizes taken by foraging moose, independent of sex, when that relationship was examined with respect to absolute or relative sizes of bites; bite size can not be invoked as an explanation for sexual segregation. Moose of both sexes overcompensated by consuming more second-year growth when feeding on smaller twigs compared with larger ones, ostensibly to adjust for lower nutritional returns in smaller twigs of current annual growth. We modelled the intake rate of moose browsing on willow with multiple-linear regression. The best model included sex, body mass of moose and density of twigs, but not shape of willows. Females had higher bite rates and rates of forage intake than males, and generally took smaller bites of greater variability. Thus, the differences in foraging behaviour between the sexes may relate to sexual dimorphism and allometric differences in digestive morphology, and ultimately to spatial segregation of sexes, as proposed by the gastrocentric hypothesis. No difference, however, occurred in the rate of intake between the sexes foraging on previously browsed willows, which resulted in our rejection of the hypothesis that selective foraging by females could lead to competitive exclusion of males.