The food limitation hypothesis of population regulation states that a stable equilibrium will exist between a population and its food resources due to a density—dependent decrease in fecundity and/or increase in mortality. This hypothesis was tested for the moose (Alces alces) by comparing regional variation in life history characteristics in four Norwegian study areas, chosen to represent a gradient both in summer and winter range conditions. The rate of body growth was most rapid in the northern study area with the best summer ranges. Lowest body growth occurred in the population living under the poorest winter conditions. After snow—free winters the rate of body growth increased substantially, leading to large annual variations in selective regimes. The peak timing of ovulation of old females in the autumn showed a latitudinal delay. Females in the alpine population, with the poorest winter conditions, had significantly later mean calving dates and produced fewest calves per year. Gestation length appears to be dependent on nutritional condition of females during pregnancy. Mortality was highest in the northern study are where most of the deaths occurred during the summer. Very few calves died during the winter. These results suggest that a stable high—density equilibrium between moose and their food resources as expected from the food limitation hypothesis is unlikely. The decrease in fecundity and the increase in mortality under poor nutritional conditions during the winter has only a small effect on the population growth rate and is therefore unlikely to have a strong regulatory effect. In the absence of large predators, this will lead to large fluctuations in population size that will overshoot the carrying capacity.

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. British Ecological Society is collaborating with JSTOR to digitize, preserve and extend access to Journal of Animal Ecology. Summary 1. Large variation was found in age of onset of reproduction among radio-collared female moose (Alces alces) in a population in northern Norway (69?N). Eight (50%) of the individuals matured at 2-5 years old, whereas age of maturity was 3-5 years or older for eight females. 2. Onset of reproduction was closely correlated with body weight. Both calf and yearling weight was significantly higher for those females that matured as 2-5 years old, compared with the other females. 3. Average calf weight differed significantly among females; however, this variation was not significantly correlated with the mother's body weight. 4. Calf weights were significantly correlated with the biomass of the herb species in the mother's summer home-range. A close relationship was found with the availability of some important forage species such as Lactuca alpina. 5. Calf body weight varied independently of birth date. Single calves of experienced mothers were significantly heavier than twins. 6. Yearling weight was significantly higher among females that stayed in the areas used as winter grounds (the central area) after they had become independent of their mother in their second summer. Females that moved to the surrounding areas had significantly lower weight gain and a delayed age at maturity, indicating a cost of dispersal. Thus, the distribution of age at maturity in a cohort will be strongly influenced by the proportion of females that succeed in establishing a home range in these areas.

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M. 2004. Lasting effects of conditions at birth on moose body mass. Á/ Ecography 27: 677 Á/687.Whether cohort effects can be retrieved in adult phenotypes depends on the possibility for individuals to compensate for a good or bad start in life. This ability to compensate may itself depend on the environment and on individual sex. In large polygynous ungulates, male reproductive success relies more on body size than the reproductive success of females, which makes them more sensitive to a bad start in life. Based on current theories of life history evolution and sexual selection, we tested the following predictions in a moose population: 1) cohort effects and year effects occur in both male and female adult body mass, but due to 2) compensatory growth, cohort effects tend to fade away with the individual's age; and 3) males are more sensitive to cohort effects than females. In support of the first prediction, we found that density and climate during the year-of-birth and the year-of-harvest affected moose body mass in both sexes. However, the magnitude of the effects of environmental conditions at birth on adult body mass decreased with increasing age, but less so in males than in females. Thus, as expected based on our third prediction, environmental conditions early in life were more influential on adult body mass of males compared to females. Such a result supports the existence of sex-specific life history tactics, with males maximising growth rate and females rather trading-off growth for reproduction. E. J. Solberg (erling.solberg@nina.no) and M. Heim, Norwegian Inst. for Nature Research,

Satellite telemetry is an increasingly utilized technology in wildlife research, and current devices can track individual animal movements at unprecedented spatial and temporal resolutions. However, as we enter the golden age of satellite telemetry, we need an in-depth understanding of the main technological, species-specific and environmental factors that determine the success and failure of satellite tracking devices across species and habitats. Here, we assess the relative influence of such factors on the ability of satellite telemetry units to provide the expected amount and quality of data by analyzing data from over 3,000 devices deployed on 62 terrestrial species in 167 projects worldwide. We evaluate the success rate in obtaining GPS fixes as well as in transferring these fixes to the user and we evaluate failure rates. Average fix success and data transfer rates were high and were generally better predicted by species and unit characteristics, while environmental characteristics influenced the variability of performance. However, 48% of the unit deployments ended prematurely, half of them due to technical failure. Nonetheless, this study shows that the performance of satellite telemetry applications has shown improvements over time, and based on our findings, we provide further recommendations for both users and manufacturers.

Habitat selection can be influenced by the distribution of the habitat types in the landscape as well as net gain in visiting patches of resources, causing individual variation in habitat selection. Moreover, the hypothesis of functional response in habitat selection predicts that the degree of selection of a resource depends on its relative availability. We used radio-telemetry data from individual moose on an island off the coast of northern Norway to evaluate whether the selection of habitat types at the landscape scale differed from the choice of habitat types within the home range, and investigated the functional response in habitat selection by relating individual habitat selection to home range characteristics. At the landscape scale, moose selected for habitat types that provided both good forage and cover, with small differences between sex and age groups. At the home range scale, all individuals selected habitat types that were associated with cover and low human impact. Habitat selection was not modified by local moose density, but was related to home range size at both spatial scales. Larger home ranges contained larger proportions of non-preferred habitat types compared to smaller home ranges. At the home range scale, the selection for a habitat type decreased with its relative availability, indicating a functional response in habitat selection. This suggests that habitat selection is modified by home range size, which influences the availability of habitat types and shapes individual habitat selection patterns. Our results support previous suggestions that analyses of habitat or resource selection should follow a multiscale approach. Both the relative availability of habitat types as well as individual variation in home range size should be accounted for in order to disentangle the complex mechanisms that contribute to shape patterns of resource selection in animals.

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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.