Kyran Kunkel

Population dynamics of a recolonizing wolf population

Breeding populations of wolves (Canis lupus) were absent from the western United States for about 50 years following their extirpation by humans in the 1930s. Here we describe the recolonization by wolves of northwestem Montana and southeastern British Columbia, from the initial production of a litter by a pair of wolves in 1982 through the mid-1990s when 3-4 packs produced litters. Sex ratio of captured wolves favored females (38/54 = 70%; X 2 = 8.96, 1 df, P < 0.005). Litter size in early summer (x = 5.3, SE = 0.4, n = 26) and in December (x = 4.5, SE = 0.5, n = 26) were relatively high compared to similar counts in established populations elsewhere. Pack size in May was unrelated to litter size in June (r s = -0.13, 23 df, P = 0.25) or the following December (r s = -0.12, 23 df, P = 0.28). Annual adult survival rate (0.80) was relatively high in this semi-protected population and was higher among residents (0.84) than among wolves that dispersed (0.66) from the study area (Z = 2.24, P = 0.025). Although dispersal was common among radiocollared wolves (19/43 = 44%), population growth within the study area averaged 20% per year from 1982 to 1995. Low human-caused mortality rates and maintenance of connectivity for wolves between this small population in the United States and larger populations in Canada will enhance the probability of persistence and expansion of this population.

Winter hunting patterns of wolves in and near glacier national park, Montana

Wolves (Cams lupus) will become an important mortality factor on ungulate populations as they recolonize the western United States. Innovative means of altering the wolf-ungulate dynamic to enhance either prey security or the predator population may be necessary to meet management objectives. From 1990 to 1996, we examined multiscale factors affecting hunting success of wolves during winter in a multi-prey system in northwestern Montana and southeastern British Columbia, Canada. Within their home ranges, wolves concentrated their hunting in wintering areas of white-tailed deer (Odocoileus virginianus). They used areas with features that facilitated travel (low snow and vegetative cover) and habitats that were favored by deer. Along their travel routes, wolves killed deer in areas with higher densities of deer and lower densities of elk (Cervus elaphus) and moose (Alces alces) than expected, based on occurrence of these prey. They killed deer in areas with greater hiding-stalking cover, less slope, and closer to water than expected, based on occurrence along wolf travel routes. More deer were killed in the main valley bottom and ravines than in other landscape classes located along travel routes. Within deer home ranges, wolves killed more deer at flatter sites and at sites with lower densities of deer.

Species-specific population dynamics of cervids in a multipredator ecosystem

In response to the natural experiment created by gray wolf (Canis lupus) recolonization of the Glacier National Park area, from 1990 to 1996 we examined population trends and female survival rates of white-tailed deer (Odocoileus virginianus), elk (Cervus elaphus), and moose (Alces alces) preyed upon by wolves, cougars (Puma concolor), bears (Ursus spp.), coyotes (Canis latrans), and humans. The effects of the complete suite of native large carnivores on prey have not been previously reported. Annual survival rates were 0.74 for 64 deer, 0.83 for 53 elk, and 0.88 for 47 moose. Cougars and wolves were the most significant sources of mortality for deer (0.09 and 0.06 respective annual cause-specific mortality rates) and elk (0.06 and 0.03 respective annual cause-specific mortality rates), and wolves and bears were the most significant sources of mortality for moose (0.03 and 0.04 respective annual cause-specific mortality rates). All age classes of deer were relatively equally vulnerable to predators, while young and old moose and elk were most vulnerable. Moose survival rates were higher where wolves were absent and where white-tailed deer were present. Deer and elk populations declined as wolf numbers increased (λ = 1.20). The moose population remained relatively stable. Predation appeared to be the primary factor limiting growth of deer and elk populations in this system. Predator-prey managers need to carefully monitor prey populations in areas wolves recolonize. Managers may be able to manipulate alternative prey densities to enhance prey populations that are affected by wolves, cougars, and bears.

The potential for large carnivores to act as biodiversity surrogates in southern Africa

Biodiversity in southern Africa is globally extraordinary but threatened by human activities. Although there are considerable biodiversity conservation initiatives within the region, no one has yet assessed the potential use of large carnivores in such actions. Surrogate approaches have often been suggested as one such way of capitalizing on large carnivores. Here we review the suitability of the large carnivore guild (i.e., brown hyaena Hyaena hyaena, spotted hyaena Crocuta crocutta, cheetah Acinonyx jubatus, leopard Panthera pardus, lion Panthea leo and African wild dog Lycaon pictus) to act as surrogate species for biodiversity conservation in southern Africa. We suggest that the guild must be complete for the large carnivores to fully provide their role as ecological keystones. The potential for large carnivores to act as umbrella and indicator species seems limited. However, self-sustaining populations of large carnivores may be useful indicators of unfragmented landscapes. Moreover, diversity within the large carnivore guild may reflect overall biodiversity. Although the global appeal of the large African carnivores makes them important international flagships, we stress that international conservation funding must be linked to local communities for them to be important also locally. In summary, we suggest that the flagship value of these large carnivores should be used to promote biodiversity conservation in the region, and that the suggested relationship between large carnivore diversity and overall biodiversity is empirically tested. Finally we suggest that direct conservation activities should focus on enhancing the keystone values of large carnivores through complete guild conservation and restoration.

FACTORS CORRELATED WITH FORAGING BEHAVIOR OF WOLVES IN AND NEAR GLACIER NATIONAL PARK, MONTANA

Abstract We examined prey selection, search distance (measured as km traveled/kill), and spatial use of recolonizing wolves (Canis lupus) in a multi-prey system in northwestern Montana, USA, and southeastern British Columbia, Canada, from 1986 to 1996. Our objective was to explore factors affecting these parameters to better understand wolf–prey relationships of recolonizing wolves. Within white-tailed deer (Odocoileus virginianus) winter ranges, wolves selectively killed elk (Cervus elaphus) over deer. Number of wolves (r = 0.67, P = 0.03), year (r = 0.68, P = 0.02), and possibly human hunter-days/elk harvested (r = 0.55, P = 0.08) were positively correlated with variation in proportion of deer killed by wolves annually. Outside of severe winters, white-tailed deer, elk, and moose (Alces alces) appeared to be equally vulnerable to wolf predation. Search distance of wolves varied by up to 12 times annually. Snow depth (r = 0.73, P = 0.03) and proportion of total kills by wolves that were deer (r = 0.66, P = 0.06) were negatively correlated with the annual variation in the total search distance of wolves. Search distance per wolf was correlated negatively with year (r = 0.66, P = 0.06) and exponentially with hunter-days/elk harvested (r = 0.70, P = 0.04). Space use by wolves may have been in response to local changes in deer abundance. Wolves appeared to select the most profitable prey species. Severe winters and wolf selection for deer, coinciding with a decrease in elk numbers, increased wolf hunting efficiency by reducing search distance. Further research is needed to determine whether reduced search distance equates to increased kill rates by wolves in this system. Based on the time, expense, and difficulty of gathering data on wolf search distance in this sytem, however, we recommend against assessing impacts of wolves on prey via measuring kill rate. Rather, we suggest monitoring impacts of recolonizing wolves by directly assessing cause-specific mortality and recruitment rates of prey species.

Diversity and depletions in continental carnivore guilds: implications for prioritizing global carnivore conservation

Large carnivores are important ecosystem components but are extinction prone due to small populations, slow growth rates and large area requirements. Consequently, there has been a surge of carnivore conservation efforts. Such efforts typically target local populations, with limited attention to the effects on the ecosystem function of predator guilds. Also, there is no framework for prioritizing these efforts globally. We compared taxonomic and functional diversity of continental carnivore guilds, compared them with the corresponding guilds during the Late Pleistocene and synthesized our results into suggestions for global prioritizations for carnivore conservation. Recent extinctions have caused taxonomically and functionally depleted carnivore guilds in Europe and North and South America, contrasting with guilds in Africa and Asia, which have retained a larger proportion of their carnivores. However, Asia is at higher risk of suffering further extinctions than other continents. We suggest three priorities of contrasting urgency for global carnivore conservation: (i) to promote recovery of the threatened Asian species, (ii) to prevent species in the depleted guilds in Europe and North and South America from becoming threatened, and (iii) to reconstruct functionally intact sympatric guilds of large carnivores at ecologically effective population sizes.

Interactive effects of species richness and species traits on functional diversity and redundancy

The importance of species diversity for ecosystem function has emerged as a key question for conservation biology. Recently, there has been a shift from examining the role of species richness in isolation towards understanding how species interact to effect ecosystem function. Here, we briefly review theoretical predictions regarding species contributions to functional diversity and redundancy and further use simulated data to test combined effects of species richness, number of functional traits, and species differences within these traits on unique species contributions to functional diversity and redundancy, as well as on the overall functional diversity and redundancy within species assemblages. Our results highlighted that species richness and species functional attributes interact in their effects on functional diversity. Moreover, our simulations suggested that functional differences among species have limited effects on the proportion of redundancy of species contributions as well as on the overall redundancy within species assemblages, but that redundancy rather was determined by number of traits and species richness. Our simulations finally indicated scale dependence in the relative effects of species richness and functional attributes, which suggest that the relative influence of these factors may affect individual contributions differently compared to the overall ecosystem function of species assemblages. We suggest that studies on the relationship between biological diversity and ecosystem function will benefit from focusing on multiple processes and ecological interactions, and that the relative functional attributes of species will have pivotal roles for the ecosystem function of a given species assembly.

Diet of wolverines (Gulo gulo) in the western Brooks Range, Alaska

Migratory caribou herds are an important component of the North American tundra. We investigated the wolverine (Gulo gulo) diet in the migratory range of the Western Arctic Caribou Herd in north-western Alaska. Within this area, caribou are absent or occur at low densities for large parts of the year, and thus show a strong seasonality in abundance. Analyses of stomach and colon contents suggested that wolverines primarily consumed caribou during the winter, and that the dietary dependence was related more to caribou mortality than to caribou abundance in the area. We also found indications that wolverines may switch between moose and caribou during periods of low caribou abundance, but that such a switch did not affect wolverine body condition. Our results thus support previous observations that wolverines primarily consume ungulates. However, a better knowledge of how alternative food sources are utilized will be necessary to predict the dietary and demographic responses of wolverines to variations in caribou abundance. We also suggest that further efforts should be made to investigate the effects of other ungulate-dependent predators on wolverine feeding ecology, because such predators may function both as competitors and as suppliers of carrion for scavenging.

Estimating Sustainable Harvest in Wolverine Populations Using Logistic Regression

Abstract Population viability analysis (PVA) is a common tool to evaluate population vulnerability. However, most techniques require reliable estimates of underlying population parameters, which are often difficult to obtain and PVA are, therefore, best used in a qualitative context. Logistic regression is a powerful alternative to traditional PVA methods but has received surprisingly limited attention. Logistic regression fits regression equations to binary output from PVA models at a specific point in time to predict probability of a binary response over a range of parameter values. We used logistic regression on output from stochastic population models to evaluate the relative importance of demographic parameters for wolverine (Gulo gulo) populations and to estimate sustainable harvest in a wolverine population in Alaska. Our analysis indicated that adult survival is the most important demographic parameter to reliably estimate in wolverine populations because it had a greater effect on population persistence than did both fecundity and subadult survival. In accordance with this, harvest rate had a greater effect on population persistence than did any of the other harvest- and migration-related variables we tested. Furthermore, a high proportion of harvested females strengthened the effect of harvest. Hypothetical wolverine populations suffered high probabilities of both extinction and population decline over a range of realistic population sizes and harvest regimes. We suggest that harvested wolverine populations must be regarded as sink populations and that source populations in combination with sufficient dispersal corridors must be secured for any wolverine harvest to be sustainable.

Bison Versus Cattle: Are They Ecologically Synonymous?

Abstract Historically, the plains bison (Bison bison Linnaeus) was the most numerous and influential grazer on the Great Plains. Today 500 000 bison occupy North America among more than 100 000 000 cattle. In an attempt to restore their historical ecological role, bison are translocated onto landscapes previously manipulated for cattle use through water and fence development. We hypothesized that bison would use these landscapes similarly to cattle, thus maintaining homogenous grazing and reducing the restoration potential of bison at a landscape scale. We quantified differences between bison populations at different locations and spatial scales (American Prairie Reserve, Malta, Montana, USA, and Grasslands National Park, Val Marie, Saskatchewan, Canada, 2010–2011) and bison and cattle at similar locations and spatial scales using behavioral observations, movement analyses, and resource selection functions. Bison and cattle differed in all behaviors (grazing, standing, bedded, moving, other); however, landscape attributes resulted in behavior differences within species. Cattle spent a higher proportion of time grazing (45–49%) than bison (26–28%) and increased time at water. Bison moved at a 50–99% faster rate than cattle, and first passage time movement analyses identified selection of bison foraging patches (11 690 ha) larger than cattle foraging patches (48–615 ha). Similar to cattle, bison avoided most vegetation communities in relation to riparian communities and selected areas closer to water. Cattle selected for high plant biomass, whereas bison selected for intermediate plant biomass. This study has implications when bison and cattle are used to meet prairie restoration objectives. For bison, large landscapes that include variation in topography and vegetation communities are required. Furthermore, limiting manmade water sources may facilitate bison grazing patterns that more closely approximate historical bison use. For livestock, reduced movement and increased time spent grazing encourage grazing practices that increase heterogeneous grazing at a pasture scale.