The realized impact of a vital rate on population growth (k) is determined by both the relative influence of the vital rate on k (elasticity) and its magnitude of variability. We estimated mean survival and reproductive rates in elk (Cervus elaphus) and spatial and temporal variation in these rates from 37 sources located primarily across the Rocky Mountain region and northwestern United States. We removed sampling variance from estimates of process variance both within and across vital-rate data sets using the variance discounting method developed by White (2000). Deterministic elasticities calculated from a population matrix model parameterized with these mean vital rates ranked adult female survival (e Scow ¼ 0.869) much higher than calf survival (e Scalf ¼ 0.131). However, process variance in calf survival (r 2 Scalf ¼ 0.039) was .11 times greater than process variance in female survival (r 2 Scow ¼ 0.003) across data sets and 10 times greater on average (r 2 Scalf ¼ 0.020;r 2 Scow ¼ 0.002) within studies. We conducted Life-Stage Simulation Analysis to incorporate both vital-rate elasticity patterns and empirical estimates of variability to identify those vital rates most influential in elk population dynamics. The overwhelming magnitude of variation in calf survival explained 75% of the variation in the population growth rates generated from 1,000 matrix replicates, compared to just 16% of the variation in k explained by variation in female survival. Variation in calf survival greatly impacts elk population growth and calls into question the utility of classical elasticity analysis alone for guiding elk management. These results also suggest that the majority of interannual variability that wildlife managers document in late-winter and spring elk surveys is attributable to variation in calf survival over the previous year and less influenced by variation in the harvest of females during the preceding autumn. To meet elk population size objectives, managers should consider the inherent variation in calf survival, and its apparent sensitivity to management, in addition to female harvest. (JOURNAL OF WILDLIFE MANAGEMENT 71(3): 795-803; 2007)

Gray wolves (Canis lupus) recolonized the Bow Valley of Banff National Park in the mid-1980s after a 30-year absence. Wolves recolonized one zone of the Bow Valley in 1985 and another in 1991, but human activity excluded wolves from a third zone throughout the study. Elk (Cervus elaphus) are the primary prey of wolves in Banff National Park. We studied the effects of wolf predation, snow depth, elk density, and human-caused mortality on the elk population growth rate in the three different wolf recolonization treatments from 1985 to 2000. We constructed a set of generalized linear models of factors affecting population growth, and used Akaike Information Criteria to guide model selection and inference. In the low wolf predation zone, elk population growth was density-dependent and limited by human-caused mortality. In the zone that wolves recolonized in 1991, elk population growth was limited by the combined effects of snow depth and wolf predation after wolf recolonization, in addition to preexisting mortality caused by humans and other predators. Our correlative approach failed to yield insights into population dynamics in the zone where wolves were present throughout the study. However, by comparing zones we demonstrate important differences in ungulate population dynamics in the presence and absence of wolf predation.

Wolf-prey research has focused on single-prey systems in North America dominated by moose (Alces alces) or white-tailed deer (Odocoileus virginianus). Elk (Cervus elaphus) are social ungulates and the main prey item of wolves (Canis lupus) in Banff National Park (BNP), Alberta. Grouping behaviour may affect the functional response of predators by changing how predators encounter and kill prey. We studied wolf predation on elk in BNP during the winters of 1997-1998 and 1998-1999 and tested how elk group size affected the availability of and encounter rates with elk groups and attack success of wolves. Wolves encountered larger elk groups than expected based on availability, and killed more elk from large groups than expected based on numbers of encounters. Elk group size increased with elk density in BNP. Increased rates of encounter with and success of attacking large elk groups, and the positive group size -density relationship may be a mechanism for density-dependent predation. We developed a predation-risk model to test the prediction that grouping will benefit individual elk, given this predation regime. Elk appeared to adopt two different strategies to minimize predation risk: living in small herds that were rarely encountered by wolves or living in large herds that reduced their predation risk through dilution.Résumé : La recherche sur les associations entre les loups et leurs proies en Amérique du Nord s'intéresse principalement aux systèmes à une seule proie, surtout l'orignal (Alces alces) ou le cerf de Virginie (Odocoileus virginianus). Le wapiti (Cervus elaphus) est un ongulé social qui constitue la proie principale du loup gris (Canis lupus) dans le parc national de Banff (BNP) en Alberta. Le comportement de regroupement peut affecter la réponse fonctionnelle des pré-dateurs en changeant la façon dont les prédateurs s'attaquent aux proies et les tuent. Nous avons étudié la prédation exercée par les loups sur les wapitis dans le parc de Banff au cours des hivers de 1997-1998 et de 1998-1999 et examiné comment la taille du groupe affecte la disponibilité des proies, la fréquence des rencontres et le succès des attaques des loups. Les loups rencontrent des groupes de wapitis plus grands que ne le permettrait de croire leur disponibilité et tuent plus de wapitis dans les grands groupes que ne le laisserait croire la fréquence des rencontres. La taille des groupes de wapitis augmente avec leur densité dans le parc. La fréquence accrue des rencontres et le succès plus grand des attaques en présence de grands groupes de wapitis, de même que la corrélation positive entre la densité et la taille des groupes, sont peut-être des mécanismes qui favorisent une prédation dépendante de la densité. Nous avons conçu un modèle de risque de prédation pour vérifier la prédiction qui veut que, chez les wapitis, le regroupement avantage les individus dans un tel régime de prédation. Les wapitis semblent adopter deux stratégies pour minimiser les risques de prédation : la vie dans de petits groupes qui ont rarement à fair...

Summary 1.Reliable estimates of population parameters are often necessary for conservation management but these are hard to obtain for elusive, rare and wide-ranging species such as wolves Canis lupus. This species has naturally recolonized parts of its former habitat in Western Europe; however, an accurate and cost-effective method to assess population trend and survival has not been implemented yet. 2.We used open-model capture-recapture (CR) sampling with non-invasive individual identifications derived from faecal genotyping to estimate survival and trend in abundance for wolves in the Western Alps between 1999 and 2006. Our sampling strategy reduced individual heterogeneity in recaptures, thus minimizing bias and increasing the precision of the estimates. 3. Young wolves had lower apparent annual survival rates (0AE24 ± 0AE06) than adult wolves (0AE82 ± 0AE04); survival rates were lower in the summer than in the winter for both young and adults. The wolf population in the study area increased from 21 ± 9AE6 wolves in 1999 to 47 ± 11AE2 wolves in late winter 2005; the population growth rate (k = 1AE04 ± 0AE27) was lower than that recorded for other recolonizing wolf populations. 4. We found a positive trend in wolf abundance, regardless of the method used. However, the abundance estimate based on snow-tracking was on average 36AE2% (SD = 13AE6%) lower than that from CR modelling, because young dispersing wolves are likely to have lower sign detection rates in snow-track surveys, a problem adequately addressed by CR sampling. 5. Synthesis and applications. We successfully implemented a new method to assess large carnivore population trend and survival at large spatial scales. These are the first such estimates for wolves in Italy and in the Alps and have important management implications. Our approach can be widely applied to broader spatial and temporal scales for other elusive and wide-ranging species in Europe and elsewhere.

After roughly a 60-year absence, wolves (Canis lupus) immigrated (1979) and were reintroduced (1995)(1996) into the northern Rocky Mountains (NRM), USA, where wolves are protected under the Endangered Species Act. The wolf recovery goal is to restore an equitably distributed metapopulation of L 30 breeding pairs and 300 wolves in Montana, Idaho, and Wyoming, while minimizing damage to livestock; ultimately, the objective is to establish state-managed conservation programs for wolf populations in NRM. Previously, wolves were eradicated from the NRM because of excessive human killing. We used Andersen-Gill hazard models to assess biological, habitat, and anthropogenic factors contributing to current wolf mortality risk and whether federal protection was adequate to provide acceptably low hazards. We radiocollared 711 wolves in Idaho, Montana, and Wyoming (e.g., NRM region of the United States) from 1982 to 2004 and recorded 363 mortalities. Overall, annual survival rate of wolves in the recovery areas was 0.750 (95% CI 5 0.728-0.772), which is generally considered adequate for wolf population sustainability and thereby allowed the NRM wolf population to increase. Contrary to our prediction, wolf mortality risk was higher in the northwest Montana (NWMT) recovery area, likely due to less abundant public land being secure wolf habitat compared to other recovery areas. In contrast, lower hazards in the Greater Yellowstone Area (GYA) and central Idaho (CID) likely were due to larger core areas that offered stronger wolf protection. We also found that wolves collared for damage management purposes (targeted sample) had substantially lower survival than those collared for monitoring purposes (representative sample) because most mortality was due to human factors (e.g., illegal take, control). This difference in survival underscores the importance of human-caused mortality in this recovering NRM population. Other factors contributing to increased mortality risk were pup and yearling age class, or dispersing status, which was related to younger age cohorts. When we included habitat variables in our analysis, we found that wolves having abundant agricultural and private land as well as livestock in their territory had higher mortality risk. Wolf survival was higher in areas with increased wolf density, implying that secure core habitat, particularly in GYA and CID, is important for wolf protection. We failed to detect changes in wolf hazards according to either gender or season. Maintaining wolves in NWMT will require greater attention to human harvest, conflict resolution, and illegal mortality than in either CID or GYA; however, if human access increases in the future in either of the latter 2 areas hazards to wolves also may increase. Indeed, because overall suitable habitat is more fragmented and the NRM has higher human access than many places where wolves roam freely and are subject to harvest (e.g., Canada and AK), monitoring of wolf vital rates, along with concomitant conservation and management strategies directed ...