Multi-scale resource selection modeling is used to identify factors that limit species distributions across scales of space and time. This multi-scale nature of habitat suitability complicates the translation of inferences to single, spatial depictions of habitat required for conservation of species. We estimated resource selection functions (RSFs) across three scales for a threatened ungulate, woodland caribou (Rangifer tarandus caribou), with two objectives: (1) to infer the relative effects of two forms of anthropogenic disturbance (forestry and linear features) on woodland caribou distributions at multiple scales and (2) to estimate scale-integrated resource selection functions (SRSFs) that synthesize results across scales for management-oriented habitat suitability mapping. We found a previously undocumented scale-specific switch in woodland caribou response to two forms of anthropogenic disturbance. Caribou avoided forestry cut-blocks at broad scales according to first- and second-order RSFs and avoided linear features at fine scales according to third-order RSFs, corroborating predictions developed according to predator-mediated effects of each disturbance type. Additionally, a single SRSF validated as well as each of three single-scale RSFs when estimating habitat suitability across three different spatial scales of prediction. We demonstrate that a single SRSF can be applied to predict relative habitat suitability at both local and landscape scales in support of critical habitat identification and species recovery.

Individually marked bighorn sheep (Ovis canadensis) were monitored to determine how seasonal and lifetime changes in mass affected the development of sexual dimorphism, and to what extent mass at a given age could predict mass of the same sheep at a later age. We trapped sheep from late May to early October each year from 1971 to 1985 in a population artificially kept at low density. Lambs and yearlings gained mass linearly from June to September, while absolute mass gain of older sheep was faster in June-July than in August-September. Males gained more mass than females each summer up to at least 3 years of age. Relative summer mass gain, calculated as a proportion of body mass at the beginning of June, was the same for male and female lambs but was greater for male than for female yearlings and 2-year-olds. With the exception of lambs, all age-classes lost mass during winter. Mass loss between September 15 and June 5 was greater for females than for males, possibly because ewes lost mass through parturition in late May. For both sexes, asymptotic mass was not reached until at least 7 years of age. Mass at 4 and 12 months of age was correlated with mass at 4 years. For all sex-age classes, mass on June 5 was negatively correlated with summer mass gain. For lambs and yearlings, winter mass loss was positively correlated with mass on September 15. Our results suggest that at low population density, sheep optimize rather than maximize summer mass accumulation. Most sexual dimorphism develops after weaning, through faster mass gain by males than by females at 1 and 2 years of age and possibly a longer season of mass gain each year for males than for females after females reach puberty.RCsumC : Nous avons CtudiC les changements de masse corporelle chez des Mouflons d7AmCrique (Ovis canadensis) marquCs individuellement au sein d7une population d7Alberta. Nous avons capturC les mouflons entre la fin mai et le dCbut octobre, de 1971 a 1985. Le gain de masse des agneaux et des jeunes de 1 an Ctait linCaire de juin a septembre, tandis que les mouflons plus igCs prCsentaient des gains de masse plus rapides en juin et juillet qu7en aoQt et septembre. Les miles ont gagnC plus de masse que les femelles a chaque annCe, jusqu7a l'ige de 3 ans. Le gain relatif de masse, calculC par rapport a la masse corporelle au dCbut de juin, Ctait le meme chez les agneaux et les agnelles, plus ClevC chez les miles de 1 an que chez les femelles de 1 an, et plus ClevC chez les miles de 2 ans que chez les femelles du meme Age. En hiver, a 17exception des agneaux, les mouflons de toutes les classes d7ige ont subi des pertes de masse. Les femelles ont subi des pertes plus importants que les miles entre le 15 septembre et le 5 juin, vraisemblablement a cause de 17agnelage a la fin mai. La masse moyenne a augment6 chez les deux sexes au moins jusqu7a l'ige de 7 ans. I1 y avait une corrClation entre la masse des mouflons a 4 mois et a 12 mois et leur masse a l'ige de 4 ans. Pour toutes les classes de sexe et d'ige, la masse au 5 juin Ctait en corrkl...

Trends in population growth can be monitored with data for key vital rates without knowledge of abundance. Although adult female survival has the highest elasticity for ungulate population dynamics, the more variable recruitment rates are commonly monitored to track local variation in growth rates. Specifically, recruitment is often measured using late winter young:adult age ratios, though these age ratios are difficult to reliably interpret given the contribution of multiple vital rates to annual ratios. We show that the supplementation of age ratio data with concurrent radio-telemetry monitoring of adult female survival allows both retrospective estimation of empirical population growth rates and the decomposition of recruitment-specific vital rates. We demonstrate the estimation of recruitment and population growth rates for 1 woodland caribou population using these methods, including elasticity and life-stage simulation analysis of the relative contribution of adult female survival and recruitment rates to variation in population growth. We show, for this woodland caribou population, that adult female survival and recruitment rates were nearly equivalent drivers of population growth. We recommend the concurrent monitoring of adult female survival to reliably interpret age ratios when managing caribou and other ungulates. ß 2011 The Wildlife Society.

The responses of a herd of migratory woodland caribou (Rangifer tarandus caribou) to timber harvesting that fragmented about 11% of their winter range in west-central Alberta were examined in this study. From 1981 to 1996, 45 caribou were radio-collared and monitored during the initiation and completion of first-pass timber harvest (50% removal). Variables examined were home-range size, daily movement rates, and distance to the nearest cut block for radio-collared individuals. Daily movement rates and individual winter range sizes decreased as timber harvesting progressed. Caribou avoided using recently fragmented areas by an average of 1.2 km. If fragmentation of the winter range continues through timber harvesting and other industrial activities, the "spacing out" antipredator strategy used by caribou may be compromised. Based on these findings, timber-harvesting strategies are recommended that (i) ensure an adequate area of usable habitat to support the current population, (ii) minimize the amount of fragmented area, and (iii) in the short term avoid presently defined core use areas.

The understanding of population dynamics is a central issue for managing large mammals. Modeling has allowed population ecologists to increase their knowledge about complex systems and better predict population responses to diverse perturbations. Mountain goats (Oreamnos americanus) appear sensitive to harvest, but the relative influence of survival and reproductive rates on their population dynamics are not well understood. Using longitudinal data on age‐ and sex‐specific survival and reproduction from a marked mountain goat population in Alberta, Canada, we built a stage‐class matrix model to predict short‐term numerical changes for 11 other goat populations in Alberta for which the only data available were from annual aerial surveys. Overall, the model provided an acceptable fit to changes in population size for 8 of 12 populations. Temporal trends in population size were underestimated in 2 populations and overestimated in another 2, suggesting that these populations had different vital rates than those of the intensively studied population. Sensitivity analyses revealed that the survival of mature females (aged 5 yr and older) had the greatest elasticity for population growth. Modeled management scenarios indicated that nonselective yearly harvest rates above 1% of goats aged 2 years and older were not sustainable over the short‐term for some populations. The simulations also revealed that small (n = 25) and medium‐size (n = 50) populations, which correspond to most goat populations in Alberta, had high extinction risk (18 to 82% over 40 years), even in the absence of harvest. Our results confirm that mountain goat populations are very sensitive to harvest, indicate that wildlife managers should prevent female harvest, and suggest that although a high demand for goat hunting exists in Alberta, most populations in this province—and probably small populations elsewhere—cannot withstand exploitation.