Prey class selection and kill rates by lynx Lynx lynx were studied in the Swiss Jura Mountains from March 1988 until May 1998 to evaluate the significance of lynx predation for roe deer Capreolus capreolus and chamois Rupicapra rupicapra. We found clear differences in the kill rates and prey class selection between lynx of different age, sex and breeding status. Male lynx killed more chamois than female lynx, and chamois was never found in kill series of subadult lynx. Family groups had the highest kill rate. They killed an ungulate every 5.0 days, compared to an average of 6.2–6.6 days for single lynx. During our 10-year study, the density of independent lynx was rather stable, ranging within 0.94–1.01 individuals/100 km². Based on the observed kill rates and the estimated lynx population structure we calculated that lynx killed 354 ± 13 roe deer and 87 ±13 chamois annually in the 710 km² study area. The magnitude of lynx predation on roe deer and chamois was primarily shaped by the lynx population structure. A decline in the number of resident male lynx reduced the number of chamois killed in the study area by ¼ of the previous number due to the difference in prey selection of male and female lynx. There was a difference in the most frequently killed age and sex classes between roe deer and chamois: lynx killed more male chamois (39%) than females or fawns, whereas in roe deer, does (38%) were most often killed. By altering adult survival, lynx predation has a significant impact on prey population dynamics. Lynx killed a maximum of 9% of the roe deer and 11 % of the chamois spring population. Considering the differences in the recruitment potential of the two prey species, lynx has a greater impact on chamois than on roe deer.

Recruitment rate has declined in many Norwegian moose Alces alces populations during the last two decades and at the same time the population size has increased and the proportion of males to females has decreased. Although density-dependent food limitation may explain part of the decrease in productivity, we evaluated to what extent the decline could also be a result of an insufficient number of males in the populations to fertilise all females. To test this hypothesis, we compared, based on ovary analyses, the age-specific variation in fecundity rates in eight Norwegian moose populations with annual variation in the adult sex ratio. Differences in female age and body mass explained a significant proportion of the variance in the probability of pregnancy. In addition, there was a significant relationship between the population sex ratio and the probability of pregnancy among 2-year-old females, but not the probability of pregnancy of older females. Because biased sex ratio only affects first-time breeders, the effect on the population recruitment rate may be limited. However, we also call attention to other possible effects of biased sex ratio, e.g. delayed parturition date, which in the long term may decrease population productivity through effects on survival and fecundity.

Age-specific mortality of large mammals follows a general pattern of high juvenile mortality followed by low adult mortality. I outline a method which models this change in mortality rate to estimate age of maturity in hunted moose Alces alces populations. Kill data indicate that first time reproducers suffer the highest mortality during the hunting season. Cohort analysis of hunter kill data was used to estimate age-specific female moose numbers and annual survival of cohorts over 18–26 years. Age at maturity was defined as age at the inflection point (highest mortality rate) of a third-order log-polynomial of annual survivorship curves. The inflection point demarcates the change in mortality rate between juvenile and adult life stages. Thus, the inflection point represents the greatest moose mortality rate during the hunting season and is likely associated with hunting mortality of inexperienced females accompanied by 6-month-old calves. I tested this method by estimating age of first reproduction (inflection point - 0.5 years) and juvenile mortality for 15 Canadian moose populations. Results indicate a wide range of age at maturity (1.7–3.0 years) and percent of juveniles that survive to this age (29–70%). Estimating age at maturity from survivorship curves provides the opportunity to test life-history theory.

We used urinary indices to determine temporal and regional patterns in nutritional status of white-tailed deer Odocoileus virginianus in nine wintering areas in northern and central Maine, USA. Winter severity was greater in the northern region, and we expected deer in that region to exhibit greater evidence for nutritional restriction. We collected an average of 26 urine samples from snow on a biweekly basis during 1 January- 31 March 1993 in each wintering area and analyzed them for ratios of urea nitrogen (N):creatinine (C), an index of nutritional status, and potassium (K):creatinine (C), an index of forage intake. Mean urea N:C ratios increased to 3.0 and 3.3 during March in northern and central Maine, respectively, suggesting that nutritional status of deer in these populations was poor. There were no differences in ratios of urea N:C between regions within time periods, except for late March when urea N:C ratios were greater in the central region. The proportions of deer exhibiting severe nutritional restriction (urea N:C ≥3.5) were greatest in March in both regions (0.16–0.31); however, proportions were highly variable among populations (range: 0–0.44). K:C ratios decreased during winter, but did not differ among regions. Our results indicate that urinary indices of free-ranging deer populations in wintering areas vary greatly, and we contend that high variability among populations is an important consideration for designing future deer research.

Time of calving in reindeer Rangifer tarandus varies between populations, but takes place around the start of the green season to ensure a stable food supply for doe and calf. Causes of variation in calving time was investigated by studying the three adjacent populations of North Ottadalen, South Ottadalen and Snøhetta, in Norway. The peak calving time was 12–14 May during 1996–1998 in North Ottadalen, 10 May in 1997 and 11 May in 1998 in South Ottadalen, and 22–26 May during 1996–1998 in Snøhetta. Comparing these results with recordings from 1969–1972, 1978 and 1985, peak calving time has been delayed by 6–8 days in North Ottadalen, and has advanced by 2–6 days in Snøhetta. In South Ottadalen, the peak calving time has remained almost constant. Analyses of covariance showed that calving time was negatively related to autumn dressed weight (P < 0.05), but not to mandible length (P = 0.15), and that calving happened later in Snøhetta than in North Ottadalen for the same level of autumn dressed weight (P < 0.05; 11.5 days) and mandible length (P < 0.05; 14 days). These results strengthen the hypothesis that delayed conception and calving is a consequence of relatively poor doe condition in autumn.

GPS collars have the potential to automatically collect large numbers of relatively accurate animal relocations. Collar costs, levels of accuracy, and satellite signal reception have been reported by other studies, but there has been little discussion of long-term performance under field conditions. Between March 1996 and April 1999, we placed 11 GPS collars on 23 individual woodland caribou Rangifer tarandus caribou for a total of 26 collar deployments. Reliability was highly variable; some collar deployments operated normally for their expected period of time, other deployments functioned for less than half of their expected lives. Collars attempted 41,822 locations and collected 15,247 3-D and 10,411 2-D locations, for an average acquisition rate of 59%. We recommend that researchers carefully consider project objectives, budget constraints, and available options such as differential correction and remote collar communication, before purchasing GPS collars.

To evaluate the effects of competition and predation on foraging by wintering granivorous dabbling ducks, we collected data on long-term changes in foraging methods used during winter in the marshes of western France. Teal Anas crecca, mallard A. platyrhynchos and pintail A. acuta start feeding in shallow areas, and later switch to deeper feeding methods. We show experimentally that the food intake rate is 1.5 times higher in shallow (5 cm) than in deep (35 cm) areas, which may explain why shallow feeding is the principal method used early in the winter season. In the field, the switch between foraging methods was neither related to the frequency of fly-overs by raptors nor to the density of competitors at a foraging site, although birds foraged deeper sooner at sites frequented more often. Thus, the potential role of interference competition remained unclear. Conversely, at each site, the proportion of deep foragers increased with increasing cumulative numbers of foragers, used as a measure of food depletion. We therefore have no evidence that disturbance by predators has an important effect on the foraging methods used, whereas competition through food depletion may play a major role.

Between autumn 1998 and spring 2000, 70 black grouse Tetrao tetrix (48 poults and 22 adults) were equipped with radio transmitters in the North Pennines, England. We recorded timing and distances of dispersal, survival rates and causes of death. First-year survival rates differed between years, but in each year were highest in late autumn prior to dispersal, when predation by stoats Mustela erminea and raptors accounted for three-quarters of deaths. First-year grouse survival was lower than that of adult birds owing to predation in the autumn and winter by raptors and stoats. The annual adult survival rate of 0.72 was higher than those found in most other European studies. By contrast, breeding success was low. Dispersal was confined to first-year hens, with distinct dispersal periods in late autumn (mean 10.3 km) and again in early spring (mean 5.8 km). Natal dispersal resulted in none of the first-year hens breeding within the study area. Adults of either sex and first-year cocks showed high site fidelity. This has practical repercussions when considering prescriptive management to aid species recovery and range expansion in relation to habitat fragmentation at both the local and regional levels.

Whereas in most of Europe the decline of the grey partridge Perdix perdix is due primarily to agricultural intensification, the Pyrenean grey partridge P. p. hispaniensis is believed to suffer from the opposite effect, namely the abandonment of agricultural practices which allows the encroachment of dense shrublands. We investigated habitat use by the Pyrenean grey partridge during the breeding season and its relationship with reproductive success and survival. The study was based on 22 radio-tagged grey partridges in a 5,800-ha upland area of the eastern Pyrenees. Habitat use was non-random, and shrubland with a shrub canopy cover higher than 40% was the most important requirement during the breeding season. In the spring, pairs that successfully reared a brood used shrublands (20–60% cover) twice as frequently as unsuccessful breeders, then in the summer halved their use of open habitats (montane grassland and shrubland with <40% cover), whereas failed breeders increased it sevenfold. Consequently, a good mixture of different cover types in the spring and summer is likely to provide the most suitable breeding habitat. There was no evidence linking the spring/summer survival of adult partridges to a particular habitat use. Current grazing practices, especially with the use of controlled burning to clear shrubby vegetation, reduce the amount of mature shrublands used by Pyrenean grey partridges. However, grazing management also delays the natural vegetation succession and hence contributes to the long-term persistence of partridge habitat. Grazing practices that prevent reafforestation and maintain a mosaic of dense and open shrublands should be encouraged in the Pyrenean uplands.