Management of large mammal populations has often been based on aerial minimum count surveys that are uncorrected for incomplete detection and lack estimates of precision. These limitations can be particularly problematic for Dall's sheep (Ovis dalli dalli) due to the high cost of surveys and variation in detection probability across time and space. The limitations of these methods have been recognized for some time, but previously proposed alternatives for sheep surveys proved to be too costly and logistically unfeasible in most circumstances (Udevitz et al. 2006). We assessed the potential for a combination of distance sampling surveys and a hierarchical modeling approach to provide a more efficient means for estimating Dall's sheep abundance by conducting aerial contour transect surveys over all sheep habitat in Gates of the Arctic National Park and Preserve (GAAR), Alaska in 2009 and 2010. We estimated the population of Dall's sheep was 8,412 (95% CI: 6,517-11,090) and 10,072 (95% CI: 8,081-12,520) in 2009 and 2010, respectively. Abundance within the Itkillik Preserve area within GAAR was 1,898 (95% CI: 1,421-2,578) and 1,854 (95% CI: 1,342-2,488) in 2009 and 2010, respectively. Estimates of lamb abundance in 2010 were more than double those of 2009 after correcting for detection bias related to group size, suggesting that the apparent estimate of lambs in the population may be biased in some years depending on the degree of aggregation. Overall, the contour transect surveys were feasible logistically, cost 70-80% less than minimum count surveys, and produced precise estimates of abundance, indicating that the application of these methods could be used effectively to increase the statistical rigor and spatial extent of Dall's sheep abundance surveys throughout Alaska. These methods could be used to improve the assessment of long-term trends in populations and productivity and provide valuable information for harvest management at both local and landscape scales at reduced costs in comparison to traditional minimum count surveys. ß 2011 The Wildlife Society.

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Long‐term wolf (Canis lupus) research programs have provided many insights into wolf population dynamics. Understanding the mechanisms controlling responses of wolf populations to changes in density, environmental conditions, and human‐caused mortality are important as wolf management becomes increasingly intensive. Competition with humans for ungulate prey has led to large‐scale wolf control programs, particularly in Alaska, and although wolf populations may sustain relatively high (e.g., 22–29%) rates of conventional harvest, control programs are specifically designed to have lasting population‐level effects. Understanding the broader impacts of wolf control efforts on the surrounding area is of particular concern for conservation agencies such as the United States National Park Service, whose mandates generally preclude the artificial reduction of populations of native predators, particularly for the primary purpose of increasing available prey biomass for human harvest. Detailed assessments of the factors influencing population vital rates (i.e., survival, natality, dispersal) and population trajectory in the context of control efforts are critical for understanding complex ecological relationships between wolves and their prey and informing management of each. Using a long‐term dataset and a powerful new integrated modeling approach, we assessed the effects of wolf control on the dynamics of a monitored wolf population residing primarily within an adjacent protected area where wolf control activities were prohibited. We monitored wolf population dynamics in Yukon‐Charley Rivers National Preserve (YUCH) in interior Alaska, USA for 22 years (1993–2014). During our study, 2 large‐scale wolf control programs were implemented in the surrounding area with the primary goal of increasing the size of the Fortymile caribou herd. We used known‐fate data based on relocations of marked wolves and repeated counts of associated pack mates to estimate survival, dispersal, and natality rates. We jointly analyzed these data using an integrated modeling approach, thereby providing inference to the entire resident, pack‐dwelling population of wolves using YUCH. Apparent survival (i.e., including mortalities and dispersals) was lower in the study area during the lethal control period, indicating a direct additive effect of control despite the prohibition of control efforts inside YUCH boundaries. Apparent survival was higher in years following winters with above‐average snowfall, corresponding with a predicted increase in ungulate prey vulnerability the following year. Extraterritorial forays were associated with lower apparent survival rates, particularly after the initiation of lethal wolf control in the surrounding area. In general, mortalities tended to occur evenly throughout the year, whereas dispersal rates increased during late winter and early spring. Dispersals accounted for approximately half of the observed losses in our collared sample across all age classes (excluding known breeders), although yearlings we...

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