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Prey behavioral responses to predation risk in wolf‐ungulate‐plant systems are of interest to wildlife managers. Using Global Positioning System data collected from telemetry‐collared elk (Cervus elaphus) and wolves (Canis lupus), we evaluated elk behavioral responses to spatial and temporal variation in wolf‐ and human‐predation risk on a winter range in the Greater Yellowstone Area, USA. We found elk changed grouping patterns and increased movement rates as predation risk increased and that these behavioral changes were habitat dependent. Elk behavioral responses to wolf‐ and human‐predation risk were similar; however, responses to human‐predation risk were stronger than responses to wolf‐predation risk. These results suggest that predation risk from wolves or human hunters may result in elk spending more time on private rangelands away from public‐land winter ranges, which may exacerbate problems of landowner tolerance of elk on livestock pastures. However, increased movement and changing grouping patterns on winter ranges may also disperse elk grazing impacts and lessen elk impacts on any one area.

A central challenge in ecology is to understand the interplay of internal and external controls on the growth of populations. We examined the effects of temporal variation in weather and spatial variation in vegetation on the strength of density dependence in populations of large herbivores. We fit three subsets of the model ln(Nt) = a + (1 + b) x ln(N(t-1)) + c x ln(N(t-2)) to five time series of estimates (Nt) of abundance of ungulates in the Rocky Mountains, USA. The strength of density dependence was estimated by the magnitude of the coefficient b. We regressed the estimates of b on indices of temporal heterogeneity in weather and spatial heterogeneity in resources. The 95% posterior intervals of the slopes of these regressions showed that temporal heterogeneity strengthened density-dependent feedbacks to population growth, whereas spatial heterogeneity weakened them. This finding offers the first empirical evidence that density dependence responds in different ways to spatial heterogeneity and temporal heterogeneity.

While many wildlife species are threatened, some populations have recovered from previous overexploitation, and data linking these population increases with disease dynamics are limited. We present data suggesting that free-ranging elk (Cervus elaphus) are a maintenance host for Brucella abortus in new areas of the Greater Yellowstone Ecosystem (GYE). Brucellosis seroprevalence in free-ranging elk increased from 0-7% in 1991-1992 to 8-20% in 2006-2007 in four of six herd units around the GYE. These levels of brucellosis are comparable to some herd units where elk are artificially aggregated on supplemental feeding grounds. There are several possible mechanisms for this increase that we evaluated using statistical and population modeling approaches. Simulations of an age-structured population model suggest that the observed levels of seroprevalence are unlikely to be sustained by dispersal from supplemental feeding areas with relatively high seroprevalence or an older age structure. Increases in brucellosis seroprevalence and the total elk population size in areas with feeding grounds have not been statistically detectable. Meanwhile, the rate of seroprevalence increase outside the feeding grounds was related to the population size and density of each herd unit. Therefore, the data suggest that enhanced elk-to-elk transmission in free-ranging populations may be occurring due to larger winter elk aggregations. Elk populations inside and outside of the GYE that traditionally did not maintain brucellosis may now be at risk due to recent population increases. In particular, some neighboring populations of Montana elk were 5-9 times larger in 2007 than in the 1970s, with some aggregations comparable to the Wyoming feeding-ground populations. Addressing the unintended consequences of these increasing populations is complicated by limited hunter access to private lands, which places many ungulate populations out of administrative control. Agency-landowner hunting access partnerships and the protection of large predators are two management strategies that may be used to target high ungulate densities in private refuges and reduce the current and future burden of disease.

The assistance of numerous people from Montana State University, Montana Department of Fish, Wildlife, and Parks, U.S. D.I. Bureau of Land Management, and private landowners is gratefully acknowledged. G. L. Dusek and D. F. Pac provided helpful suggestions and moral support during data collection, analysis, and writing and reviewed several drafts of this manuscript. H. E. Jorgensen assisted with vegetation work and developed a computer program to calculate winter severity indices. J. P. Weigand provided administrative support for the project and reviewed drafts of this manuscript. S. M. Hinkins provided statistical consultation, and C. S. Bittinger helped with the use of statistical packages.

Traditional elk habitat management on public land has focused on providing security habitat for bull elk during the hunting season to provide for both adequate hunter opportunity and bull survival. This paradigm has given less consideration to adult female elk habitat use, patterns of adjacent land ownership, and hunter access. This paradigm also was developed when elk population sizes were much smaller in many areas. In many Rocky Mountain states, the focus of elk population management has recently shifted to reducing or maintaining elk population sizes, necessitating a better understanding of the implications of security habitat management, as well as patterns of adjacent land ownership and hunter access, on adult female elk. We addressed this need by testing the hypotheses that during the hunting season: 1) adult female elk selection for areas prohibiting or limiting hunter access is stronger than elk selection for publicly owned and managed elk security habitat, 2) these effects occur during the archery hunting period and intensify during the rifle hunting period, and 3) the effects of hunter access on selection are consistent among herds that occupy landscapes characterized by a matrix of public and private lands. We used global position system locations collected from 82 females in 2 different Greater Yellowstone Ecosystem (GYE) elk herds to evaluate effects of hunter access, security habitat as defined by the Hillis paradigm, and other landscape attributes on adult female elk resource selection during the pre‐hunting, archery, rifle, and post‐hunting periods. We found that female elk selection for areas restricting public hunting access was stronger than selection for security habitat in both study areas, and that the density of roads open to motorized use was the strongest predictor of elk distribution. Increases in selection for areas that restricted hunting access occurred during the rifle hunting period, and we did not find consistent evidence these movements were triggered by the archery hunting period. Our results provide evidence that in landscapes characterized by a matrix of public and privately owned lands, traditional concepts of elk security habitat need to be expanded to also include areas that restrict hunter access to plan for elk population management that is regulated through adult female harvest. Future efforts should investigate whether elk use of areas that restrict hunter access are flexible behavioral responses to hunting risk, or if these behaviors are passed from generation to generation such that a learned pattern of private land use becomes the normal movement pattern rather than a short‐term behavioral response. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

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