Registered users receive a variety of benefits including the ability to customize email alerts, create favorite journals list, and save searches.
Please note that a BioOne web account does not automatically grant access to full-text content. An institutional or society member subscription is required to view non-Open Access content.
Contact firstname.lastname@example.org with any questions.
Forester T. Grasaas' data on numbers of capercaillie Tetrao urogallus cocks and hens observed at leks and clutch sizes in Vegårshei, southern Norway, during 1953–1962 (high population level) and 1969–1978 (low population level) were analysed with regard to bilberry Vaccinium myrtillus production, autumn population indices and snow conditions in spring. From the mast depression hypothesis, it was predicted that the number of capercaillies counted at leks and the mean clutch size should be high after high seed crops (masts) of bilberry, usually produced at intervals of 3–5 years. In stepwise regression models, both the bilberry index of the preceding year and the autumn population index one (hens) or two (cocks) years earlier contributed to explain the mean number of capercaillies counted at leks during 1970–1978. Capercaillie clutch sizes were highest in years with early thaw, but the effect was significant only for the period 1969–1978. For this period, there also was a positive effect of the bilberry index and a negative effect of the autumn population index of the previous year. It is concluded that the synchronous population fluctuation of grouse and voles in Norway and Sweden cannot be explained by the alternative prey hypothesis alone, and that food quality should also be considered as a possible contributing factor when analysing population fluctuations of grouse and other herbivorous species.
The ability of Eurasian beavers Castor fiber to recognise different predator odours has received little research, nor has the use of predator odours to deter Eurasian beavers from damaging agricultural crops, fruit and forest trees. Recognition of and response to predator odours by prey is of adaptive significance because it reduces predation risk. We tested the hypothesis that predator odours decrease foraging and predicted that: human and wolf Canis lupus odour would decrease foraging more effectively than other predator odours. Our results showed that all tested predator odours (red fox Vulpes vulpes, river otter Lutra lutra, lynx Lynx lynx, wolf and brown bear Ursus arctos), except those from human and dog Canis familaris, significantly decreased foraging during summer. River otter, red fox, lynx, wolf and brown bear odours had the strongest effects during summer. During autumn, river otter odour was significantly more effective than the other predator odours, except those from lynx, human and red fox, in decreasing foraging. Only odour from river otter, human, lynx and red fox had a significantly stronger effect than the three controls during autumn. Overall, the river otter odour was most effective in decreasing foraging. Odours from predators sympatric with the Eurasian beaver did not have a larger effect than those of originally sympatric, but now absent species. Beavers ate more sticks with predator odour in autumn than in summer. Our results have clear practical implications, and several are suggested.
We studied the distribution of rutting pits and the role of scraping during the rut in a south Swedish population of fallow deer Dama dama. Pits are large patches of bare soil found at the centre of mating stands where most of the rutting activities take place. The location of rutting pits in the study area was not significantly different from a random distribution in any of the five years of the study. Thus, there was no evidence of aggregation of rutting pits. Scrapes are small patches of bare soil found throughout the areas of deer activity. Only bucks showed any interest in scrapes. Within a 10 day period half the scrapes were rescraped at least once. Larger scrapes were more frequently rescraped than smaller ones. Frayings, i.e. removal of bark and subsequent scent marking on bushes and small trees close to scrapes, also had a positive effect on the frequency of rescraping. Artificial scrapes made close to real scrapes attracted less rescraping than natural scrapes. This might indicate that a scrape is preferentially rescraped by the buck who first created it. We found a tendency that scrapes were made in the direction of other stands/ pits, possibly indicating that they may function as territorial marks. However, the fallow deer bucks in our study do not seem to mark territorial boundaries, rather the intensity of markings tends to decrease with distance from the rutting pit suggesting that scraping may instead be used in male status signalling.
We test whether high moose density results in smaller moose, slower growth rates, lower reproductive rates, and more variable year-to-year population size by comparing demographic characteristics of 15 Canadian moose Alces alces populations that spanned a range of population density (0.08–4.5 moose/ km2). Density negatively affected growth rate, reproductive rates and recruitment. We argue that primary productivity, measured as percent forest cover, and natural predation link density to reproduction in moose. Populations that lived in greater forest cover and experienced greater natural predation were associated with more predictable year-to-year variation in population size. In contrast, moose populations living in areas of low forest cover and low natural predation experienced greater density independent food limitation and greater unpredictability in population size. Thus, moose populations living in areas of low primary productivity and low natural predation show less persistence and require greater conservation efforts.
The annual age- and sex-specific patterns of harvest mortality in a Norwegian moose Alces alces population during a period of 17 years for females and 24 years for males were estimated using cohort analysis. In males the harvest mortality increased with age, whereas in females the pattern was U-shaped with higher harvest mortality of less fecund young (1–3 year) and old (≥ 10 years) age classes, and lower harvest mortality of prime age (4–9 years old) females. In both sexes, the calf harvest mortality was low, although it increased with increasing calf quotas following a change from an indiscriminate to a sex- and age-specific hunting system during the study period. In adult males, the mortality pattern was opposite of what was expected based on the previously reported higher susceptibility to hunting of young than old males, indicating that hunter selectivity for large (old) males affected the pattern. Moreover, the selectivity of the hunters decreased as the hunting pressure increased, suggesting that the hunters became less selective when the mean time available per moose in the quota decreased. Among adult female age groups, the variation in harvest mortality increased with the proportion of calves per female in the population prior to hunting. This was mainly because of relatively higher mortality of post-prime females, supporting our expectation that hunters avoid shooting females with calves and thus increase the harvest of less fecund age groups during high recruitment years. The observed selectivity led to harvest mortality that differed significantly from patterns of natural mortality, even where the mortality is mainly due to wolves Canis lupus and bears Ursus arctos. This may have consequences for the life history evolution of both male and female moose. The potential ecological, evolutionary and management implications of the results are discussed.
Cast white-tailed deer Odocoileus virginianus antlers from the McAlester Army Ammunition Plant (McAAP) in southeastern Oklahoma were used to assess distributions of selected antler characteristics, illustrate variation in antler development in a white-tailed deer population under a quality deer management program, and determine if harvest statistics accurately reflect antler characteristics of the population. We systematically searched cultivated food plots on the McAAP during the winter of 1995 for freshly cast antlers (N = 77). Gross scores of antlers averaged 41.9 but were slightly skewed (skewness = -0.283) towards larger antlers, suggesting that a large proportion of the population is comprised of mature animals (≥3.5 years). Mean beam length, basal circumference, and number of points were significantly greater among cast antlers than among antlers of deer harvested by hunters. These data illustrate the results of a management and harvest strategy designed to produce quality white-tailed deer, and indicate that data collected from hunter harvested deer may not be representative of the population.