Impacts of Landscape Change on Wolf Restoration Success: Planning A Reintroduction Program Based on Static and Dynamic Spatial Models
Carroll, C.; Phillips, M.K.; Schumaker, N.H.; Smith, D.W. Conservation Biology 17/2, (April 2003), 536-548
Mammalian carnivores are increasingly the focus of reintroduction attempts in areas from which they have been extirpated by historic persecution. We used static and dynamic spatial models to evaluate whether a proposed wolf reintroduction to the southern Rocky Mountain region (U.S.A) would advance recovery by increasing species distribution beyond what might be expected through natural range expansion. We used multiple logistic regression to develop a resource-selection function relating wolf distribution in the Greater Yellowstone region with regional-scale habitat variables. We also used a spatially explicit population model to predict wolf distribution and viability at several potential reintroduction sites within the region under current conditions and under two contrasting predictions of future landscape change. Areas of the southern Rocky Mountains with resource-selection-function values similar to those of currently inhabited areas in Yellowstone could potentially support >1000 wolves, 40% within protected areas and 47% on unprotected public lands. The dynamic model predicted similar distribution under current conditions but suggested that development trends over 25 years may result in the loss of one of four potential regional subpopulations and increased isolation of the remaining areas. The reduction in carrying capacity due to landscape change ranged from 49% to 66%, depending on assumptions about road development on public lands. Although much of the wolf population occurs outside core protected areas, these areas remain the key to the persistence of subpopulations. Although the dynamic model's sensitivity to dispersal parameters made it difficult to predict the probability of natural recolonization from distant sources, it suggested that an active reintroduction to two sites within the region may be necessary to ensure low extinction probability. Social carnivores such as the wolf, which often require larger territories than solitary species of similar size, may be more vulnerable to environmental stochasticity and landscape fragmentation than their vagility and fecundity would suggest.
The Impacts of Human Residences, Roads, and Cattle on Wolf Recovery in the Ninemile Valley, Montana
Jiminez, M.; Pletscher, D.H.; Ream, R., Beyond 2000: Realities of Global Wolf Restoration (2000)
Gray wolves (Canis lupus) began recolonizing remote areas in northwestern Montana in 1982. Human tolerance towards wolves allowed wolves to expand their range into more populated regions of the Rocky Mountains. As wolves recolonized valley bottoms where humans live and raise livestock, potential conflicts between wolves and humans increase. Wolves recolonized Ninemile Valley in western Montana in 1990. From 1990 to 1999, at least 45 different wolves inhabited Ninemile at various times. Pack size ranged from 1 to 12 wolves, with 9 successful litters totaling at least 40 pups. We monitored wolves in the Ninemile Valley for 8 years to examine how human activities influenced feeding ecology and habitat use of wolves, and how wolves interacted with cattle. Scat analysis indicated that wolves fed extensively on white-tailed deer (Odocoileus virginianus). Five dogs were killed by wolves and 5 dogs were attacked but survived. Wolves frequently fed on cattle carcasses but only rarely killed cattle. Wolves killed 2 steers in 1991, 1 steer in 1992, 1 calf in 1996, and 4 calves in 1998. Four wolves were removed by lethal control in 1998. Wolves used closed roads to access den and rendezvous sites in areas that were relatively undisturbed by humans. We examined wolf/cattle interactions by intensively monitoring radio-collared wolves and domestic cows grazing on U.S. Forest allotments. Based on simultaneous wolf/cattle radio locations, we determined that wolves were routinely within close proximity of livestock but continued preying on white-tailed deer. Wolves persist in Ninemile Valley despite occasional conflicts with humans and contribute to wolf recovery.
Implications of Free-Grazing Cattle on Wolf (Canis lupus) Conservation in Portugal
Alvares, F.; Petrucci-Fonseca, F., Beyond 2000: Realities of Global Wolf Restoration (2000)
Coexistence of wolves and wild or free-grazing cows (Bos taurus) and horses (Equus caballus) is rare through the wolf range, although it occurs in almost all [of the] North Iberian Peninsula. This study presents data collected to assess the ecological relation between wolves and free-grazing cattle in Peneda-Geres National Park (Northwest Portugal), to evaluate the causes and consequences of the high conflict between wolves and shepherds and to propose guidelines to minimize the wolf's predatory impact.
Twelve packs inhabit the study area, with a mean density of 3.7 wolves/100 km2, in autumn. However, in some mountains, with high numbers of free-grazing cattle, wolf density can reach 6.0 wolves/100 km2, one of the highest wolf densities in [the] Iberian Peninsula, and even in Europe. The wolf diet is based on livestock, with almost 50% frequency of cows and horses. Wolves exhibit a strong selection for horses but not for cows, showing a preference for cows and horses less than one year old (90% and 70%, respectively)....
In Portugal, all livestock damages caused by wolves are compensated, and the study area is the region where more livestock damages occur and more indemnities are paid to cattle breeders. These damages maintain the old man and wolf conflict. One of the main threats to the wolf's survival in this area is the illegal persecution by man (mainly through shooting), motivated by these economic and social issues. However, in areas where free-grazing livestock is reared, poison is used to control wolf numbers, leading to the extermination of a high number of wolves in a short period of time.
In order to minimize wolf predatory impact [on] free-grazing livestock, several measures must be implemented, such as the proposal of a fairer compensation programme and the use of autocthonous breeds and the maintenance of traditional ways of grazing and herding....
Improving of Wolf Habitat in SW European Countries
Palacios, F., World Wolf Congress 2003
The present conditions of wolf habitats in western European countries, which have been created by humans bent on uncurtailed development and the use of natural resources to maximize benefits, are a trap for this wild species. The domestication and the development of free-grazing livestock raising practices have created the circumstance in which the wolf has become a livestock predator. This trait serves to justify those who obtain a profit from the wolf conflict (public authorities, hunters, consultants) to authorize or support wolf hunting, thus leading to a chaotic management scheme that sanctions persecution by any method. Those who are satisfied with managing wolves in humanized environments in western European countries and those who benefit economically from the wolf conflict should understand that it is necessary to contribute politically and economically to improving wolf habitats. The necessary improvements in habitat include prohibiting free-grazing practices (extensive grazing) in open areas, promoting semi-extensive grazing practices supervised by professional shepherds and dogs who rotate and watch livestock by day and guard them at night, measures to ensure that livestock carrion remains out of the reach of wolves, promoting wild ungulates and restoring their habitat, prohibiting big game fences, and prohibiting the persecution of wolves that feed on wild prey. The most viable option for the continued existence of the wolf in western European nations, which have wealthy, modern, democratic and civilized citizens who are supposedly concerned about the conservation of biological diversity, is to guarantee that wolves and their natural functions can be integrated into natural settings and that the species can cease to live traumatically.
Integrating Effects of Hunting Policy, Catastrophic Events, and Inbreeding Depression, in PVA Simulation: the Scandinavian Wolf Population as an Example
Nilsson, T., Biological Conservation, 115/2, 227 (13pp)
Focusing on the wolf Canis lupus in Scandinavia as an example, criteria are proposed and an analysis performed to assess the effect on extinction risk of various control policies, while accounting simultaneously for effects of inbreeding depression and potential catastrophic events. Each control policy is characterized by a hunting pressure (the increase caused by hunting of annual mortality rates) combined with a hunting threshold (the population size below which hunting is not permitted). Catastrophes are taken into account by including the persistence of a severe catastrophe in the criterion for population viability. Based on these criteria, the results suggest that only a very limited amount of hunting should be permitted at low population sizes. The results also illustrate the importance of including a long-term perspective in modelling threatened populations.
Integrating Epidemiology into Population Viability Analysis: Managing the Risk Posed by Rabies and Canine Distemper to the Ethiopian Wolf
Haydon, D.T.; Laurenson, M.K.; Sillero-Zubiri, C., Conservation Biology, 16/5 (October 2002), 1372 (14pp)
Infectious disease constitutes a substantial threat to the viability of endangered species. Population viability analysis (PVA) can be a useful tool for directing conservation management when decisions must be made and information is absent or incomplete. Incorporating epidemiological dynamics explicitly into a PVA framework is technically challenging, but here we make a first attempt to integrate formal stochastic models of the combined dynamics of rabies and canine distemper into a PVA of the Ethiopian wolf (Canis simensis), a critically endangered canid. In the absence of disease, populations in habitat patches of every size were remarkably stable and persistent. When rabies virus was introduced, epidemics, assumed to arise from sporadic dog-to-wolf transmission, caused extinction probabilities over 50 years to rise linearly with the force of infection from the dog reservoir and particularly steeply in smaller populations. Sensitivity analysis revealed that although the overall pattern of results was not altered fundamentally by small to moderate changes in disease-transmission rates or the way in which interpack disease transmission was modeled, results were sensitive to the process of female recruitment to male-only packs. Completely protecting wolf populations from rabies through vaccination is likely to be impractical, but the model suggested that direct vaccination of as few as 20–40% of wolves against rabies might be sufficient to eliminate the largest epidemics and therefore protect populations from the very low densities that make recovery unlikely. Additional simulations suggested that the affect of periodic epidemics of canine distemper virus on wolf population persistence was likely to be slight, even when modeled together with rabies....
Interactions Between Wolves and Dogs in Scandinavia
Karlsson, J., World Wolf Congress
Wolf depredation on dogs is one of the most important factors for negative perceptions of wolves in Scandinavia, and thereby also a major issue for wolf management. Dogs are mainly attacked while used for hunting. Compensation is paid for all dogs killed or injured by wolves after field confirmation by trained personnel. This study presents data on wolf attacks on dogs in Scandinavia and the factors influencing the number of dogs attacked inside and outside wolf territories. The results presented are based on five different sub-studies carried out between 1999 and 2002: (1) Telephone interviews of 500 hunters with hunting dogs in 5 different wolf territories for 3 consecutive years, aiming at describing the hunting dog population and intensity of hunting dog use in each territory. (2) Selectiveness of wolf depredation. Sex, age, race etc. on attacked dogs are compared to corresponding data for the total hunting dog population in each territory. (3) Experimental exposure of radio-collared wolves to barking dogs. (4) Test of dogs interest in following wolf tracks. The number of dogs attacked could not be explained by some wolf individuals being more prone to attack dogs than others. Instead the number of attacks was a function of dog use intensity (hunting) and the number of wolves in the territory. The status of the wolves; dispersing, scent marking or having pups was of less importance. No selectivity for dogs of certain breeds was found; all breeds were attacked in proportion to their use.
Interspecific Competition Between Recolonizing Wolves and Coyotes: Implications for Pronghorn Persistence in Grand Teton National Park
Berger, K., Rocky Mountain Wolf Recovery 2003 Annual Report
The purpose of this study is to investigate the effects of recolonizing wolves on pronghorn (Antilocapra americana) population persistence, as mediated by changes in the distribution and abundance of coyotes, a major predator of neonate pronghorn. Specific questions to be addressed are: 1) Are coyotes limited by competition with wolves? 2) If so, by what mechanism(s) do wolves alter coyote densities? And 3) What effects do changes in coyote density have on pronghorn fawn survival? Coyote densities, spatial dynamics, mortality rates, and causes of mortality will be contrasted at sites with high, moderate, and low levels of wolf activity to look for evidence of interference competition and mesopredator release. Pronghorn fawn mortality rates and causes will be compared across sites to determine how differences in coyote density affects neonate survival. Factors that may be influencing fawn recruitment, such as fecundity, birth weight, sex, timing of birth, and habitat availability, will also be explored among sites. The results of this study will be evaluated using sensitivity analysis to address implications for conservation of pronghorn in Grand Teton National Park.
Intra-hair Stable Isotope Analysis Implies Seasonal Shift to Salmon in Gray Wolf Diet
Darimont, C. & T. Reimchen, Canadian Journal of Zoology, 80 (September 2002): 1638-1642 (5 pp)
Seasonal shifts in diet are widespread, but our ability to detect them can be limited. Comparisons of stable isotope signatures in metabolically inert tissue portions grown at different times are inadequately exploited in dietary reconstructions. We propose that segments of guard hair can index diet to periods of growth (i.e., seasons differing in resource availability). We examined inter-hair d13C and d15N signatures from gray wolves (Canis lupus) of British Columbia to test whether the bulk of enriched (marine-derived) nutrients was assimilated during fall, the peak of salmon (Onchorynchus spp.) migration. In five animals, we detected a seasonal dietary shift: relatively more 13C and 15N was assimilated during fall than during summer, suggesting use of salmon during fall. Twelve wolves and both controls showed no seasonal shift in diet. Using salmon when available may be adaptive, given its predictability, spatial constraint, caloric content, and lower potential to inflict injury relative to that imposed by large mammals. Our study complements others that also used novel and fine-scale isotope approaches and may permit the identification of otherwise undetectable niche differentiation among conspecifics or heterospecifics.