Completed Projects
Effects of Trophy Hunting on Grizzly Bear Habitat Use, Population Growth, and Persistence
R.B. Wielgus & others
This project tested and rejected the “increased reproduction hypothesis” whereby mortality of adult males was believed to result in increased production and survival of young due to compensatory, density dependent effects. The research supported the “decreased reproduction hypothesis” whereby mortality of resident adult males resulted in increased immigration by potentially infanticidal males, increased sexual segregation, and reduced reproduction, population growth, and persistence. This work has had a major impact on grizzly bear/brown bear management and conservation in North America and Europe. Trophy hunting of threatened grizzly bear populations has been discontinued and several grizzly bear reserves have been established in BC, Canada as a result of this work.
Wielgus, R.B. 2002. Minimum viable population and reserve sizes for naturally regulated grizzly bears in British Columbia. Biological Conservation. 106 (3): 381-388. PDF
Wielgus, R.B., F. Sarrazin, R. Ferierre, and J. Clobert. 2001. Estimating effects of adult male mortality on grizzly bear population growth and persistence using matrix models. Biological Conservation. 98:293-303. PDF
Wielgus, R.B., and F.L. Bunnell. 2000. Possible negative effects of adult male mortality on female grizzly bear reproduction. Biological Conservation 93:145-154. PDF
Wielgus, R.B., and F.L. Bunnell. 1995. Tests of hypotheses for sexual segregation in grizzly bears. Journal of Wildlife Management. 59(3):552-560.
Wielgus, R.B., and F.L. Bunnell. 1994. Dynamics of a small, hunted brown bear population Ursus arctos in southwestern Alberta, Canada. Biological Conservation. 67:161-166.
Wielgus, R.B., and F.L. Bunnell. 1994. Sexual segregation and female grizzly bear avoidance of males. Journal of Wildlife Management. 58(3): 405-413.
Wielgus, R.B., F.L. Bunnell, W.L. Wakkinen, and P.E. Zager. 1994. Population dynamics of Selkirk Mountain grizzly bears. Journal of Wildlife Management. 58(2):266-272.
Effects of Forestry on Grizzly Bear Habitat Use
R.B. Wielgus & others
This research program tested the widely accepted, but untested, hypotheses that grizzly bears avoid managed forests and forestry roads. Grizzly bears did not avoid managed forests and forestry-only roads, but they did avoid open roads and adjacent forest types. Forestry activities by themselves (clearcuts, young second growth forests, restricted forestry-only roads) had little or no impact on grizzly bear habitat use. Human recreational use of open forestry roads had the only observed negative effect on grizzly bear habitat use and population growth. Forest road management in the US and Canada has been modified as a result of this work.
Wielgus, R.B., and P.R. Vernier. 2003. Grizzly bear selection of managed and unmanaged forests in the Selkirk Mountains. Canadian Journal of Forest Research. 33:822-829. PDF
Wielgus, R.B., PR. Vernier, and T. Schivacheva. 2002. Grizzly bear use of open, closed, and restricted forestry roads. Canadian Journal of Forest Research. 32 (9): 1597-1606. PDF
Effects of Sex and Age on Black Bear Conifer Damage and Control
Gail Collins, G.M. Koehler & R.B. Wielgus
This project was part of Gail Collins’s M.S. program. We examined the commonly held belief that all sexes and ages of black bears cause conifer damage and that hunting is an effective control measure. Female black bears caused 89% of total conifer damage but comprised only 31% of kills. Males caused only 11% of conifer damage but comprised 69% of kills. We suggested that current lethal control measures were relatively ineffective for reducing conifer damage and that supplemental feeding may be a much more effective method for reducing damage. Methods of damage control in some parts of the Pacific North West have modified as a result.
Collins, G.H., R.B. Wielgus, and G.M. Koehler. 2002. Effects of sex and age on American black bear conifer damage and control. Ursus 13: 231-236. PDF
Cougar Predation and Population Growth of Sympatric Mule Deer and White-Tailed Deer
Hugh Robinson, J. Gwilliam, & R.B. Wielgus
This project was part of Hugh Robinson’s M.S. program. We tested if patterns of total mortality (predation rate) for white-tailed deer and mule deer were consistent with the apparent competition hypothesis. Results indicated that white-tailed deer were 3 times as numerous as mule deer. Mule deer were declining and white-tailed deer were increasing. Predation by cougars accounts for most of the difference in growth rates. Predation was inversely density dependent on mule deer but density dependent on white-tailed deer. These findings support the Apparent Competition hypothesis. Forest fragmentation and agriculture may have resulted in increased numbers of white-tailed deer. This appears to have resulted in increased numbers of cougars and increased predation on mule deer. White-tailed deer were reduced in parts of BC as a result of this work.
Robinson, H.S., R.B. Wielgus, and J. Gwilliam. 2002. Cougar predation and population growth of sympatric mule deer and white-tailed deer. Canadian Journal of Zoology. 80: 556-568. PDF
Effects Of Forest Fragmentation on Cougar Predation of Endangered Mountain Caribou
Don Katnik & R.B. Wielgus
This project was part of Don Katnik’s Ph.D. program. We tested the hypothesis that forest fragmentation results in increased predation by cougars on the last remaining endangered mountain caribou population in the lower US. Results suggest that forest fragmentation of old-growth forest results in increased expansion by primary prey (white-tailed deer) and subsequent increased predation on secondary prey (mountain caribou) by cougars.
Katnik, D.D., and R.B. Wielgus. 2005. Landscape proportions versus Monte Carlo simulated home ranges for estimating habitat availability. Journal of Wildlife Management. 69 (1): 20-32. PDF
Minimum Population Size for Grizzly Bears in the North Cascades of WA and BC
Kimberley Romain, R.B. Wielgus & others
This project was part of Kim Romain’s M.S. program. We estimated minimum population size of the North Cascades grizzly bear population in NW WA and southern BC by using DNA hair snags. We compared numbers of hair captures in the North Cascades to numbers of hair captures for known density bear populations in the adjacent Selkirk Mountains (ID) and Cabinet Yaak (MT) Grizzly Bear Recovery Areas. Results suggest that grizzly bears are demographically extirpated (<30 animals) in the North Cascades and require augmentation for recovery.
Romain-Bondi, K.A., R.B. Wielgus, L. Waits, W.F. Kasworm, M. Austin, and W. Wakkinen. 2004. Density and population size estimates for North Cascades grizzly bears using DNA hair sampling techniques. Biological Conservation. 117: 417-428. PDF
Cougar Population Dynamics in the Northwest
Catherine Lambert, H.S. Robinson, H.S. Cooley (Cruickshank), D.D. Katnik, R.B. Wielgus & others
This project was part of Catherine Lambert’s M.S. program. We determined cougar reproduction, survival, and population growth rates in the Selkirk Mountains of northern Washington, northern Idaho, and southern B.C. . We also tested the commonly accepted hypotheses that cougar populations are rapidly increasing in the area (as suggested by increased complaints of human-cougar conflicts). Contrary to popular belief – cougar populations were not increasing but were rapidly declining (-20%/year). Increased cougar-human conflicts appear could be due to the very young age structure (no dominant adult males left) caused by excessive hunting.
Lambert, C, R.B. Wielgus, H.S. Robinson, H. Cruickshank, D.D. Katnik, R. Clarke, and J. Almack. 2006. Dynamics and viability of a cougar population in the Pacific Northwest. Journal of Wildlife Management.70(1): 246-254. PDF
Cougar Prey Selection in a Mule Deer & White-tailed Deer Community
Hilary Cooley (Cruikshank), H.S. Robinson, C. Lambert, & R.B. Wielgus
This project was part of Hillary Cooley’s M.S. program. We determined cougar prey selection (use vs. availability) and species-specific kill rates (kills/unit time, cougar) in two mule deer/white-tailed deer communities. We also tested the prey-switching hypothesis (stabilizing) and the apparent competition hypothesis (destabilizing). White-tailed deer were the primary prey of cougars throughout the year, but cougars selected for mule deer during the summer when white-tails moved into mule deer range. We rejected the prey-switching hypothesis but accepted the apparent competition hypothesis. Cougar predation is destabilizing and may cause mule deer populations to decline in a depenstaory manner when white-tailed deer are sympatric. White-tailed deer expansion appears responsible for mule deer population declines in our study areas.
Cooley, H.S., H.S. Robinson, R.B. Wielgus, and C. Lambert. 2008. Cougar prey selection in a mule deer and white-tailed deer community. Journal of Wildlife Management 72 (1): 99-106. PDF
Lynx Habitat Selection in North Washington
Ben Maletzke, G.M. Koehler, R.B. Wielgus & others
This project was part of Ben Maletzski’s M.S. program. We examined the relationships between forest composition, anthropogenic disturbance, and lynx habitat selection during winter in order to identify important habitats for lynx recovery in northern WA. Lynx selected for relatively dense, higher elevation, Englemann Spruce – subalpine Fir forests (ESSF) and selected against lower elevation, open, pine forests, cutblocks, and burns. Lynx trail sinuosity (hunting behavior) was much higher in spruce-fir forests with high densities of hares than in the other forest types. Older spruce-fir forests appear to be very important for lynx recovery in northern WA.
Maletzke, B.T., G.M. Koehler, R.B. Wielgus, and K.B. Aubry. 2008. Habitat characteristics associated with Canada lynx hunting behavior in Washington. Journal of Wildlife Management (In Press).
Koehler, G.M., B.T. Maletzke, J.A. von Kienast, K.B. Aubry, R.B. Wielgus, and R.H. Naney. 2008. Habitat fragmentation and its potential influence on the persistence of lynx populations in Washington State. Journal of Wildlife Management (In Press).
Quantitative Population Ecology of Pyrenees Brown Bears in France and Spain
G. Chapron, R.B. Wielgus & others
This project was part of R. Wielgus’ sabbatical with the Museum National de Histoire Naturelle (MNHN) Dept Ecologie et Gestation de la Biodiversite and the Centre National Recherche de Scientifique (CNRS) Lab d’Ecologie in Paris France. We analyzed a long-term time series of brown bear monitoring data to estimate demographic parameters such as age-specific survival and reproduction. Contrary to popular, previous belief, we found that Pyrenean brown bears were not declining because of high human-caused mortality, but were declining because of low cub production and survival. Reasons for the low reproductive success were either the male-biased sex ratio resulting in sexually selected infanticide and habitat segregation and/or inbreeding depression. PVA indicated that the addition of a few transplanted females should result in population recovery. The French government began a transplant augmentation program of females in Spring 2006.
Chapron, G., R.B. Wielgus, P. Qinette, and J. Camarra. 2007. Population demography, augmentation, and viability for endangered Pyrenean brown bears. Biological Conservation (Submitted).
Chapron, G., R.B. Wielgus, A. Lambert, and J. Clobert. 2007. Overestimates of maternity and population growth rates for grizzly bears and other animals with extended parental care. Journal of Applied Ecology (Submitted).
Effects of White-Tailed Deer on Cougar Predation of Mule Deer: A Test of the Apparent Competition Hypothesis
Hugh Robinson, H.S. Cooley, B.T. Maletzke, R.B. Wielgus & others
This project was part of Hugh Robinson’s Ph.D. program. Mule deer are declining throughout much of the western US at the same time as white-tailed deer and cougars appear to be increasing. We hypothesized that apparent competition (expansion by white-tails and corresponding increased predation by cougars on sympatric mule deer ) is responsible for these declines. We tested the apparent competition hypothesis by radio monitoring cougars and deer for aggregative (#cougars/unit area), functional (#kills/cougar), numerical (#offspring/cougar), and total (mule deer mortality rate) responses in Kettle Falls, Republic, and Selkirk Mountains WA. The apparent competition hypothesis predicted that all 4 responses will increase with increasing white-tailed deer density and vice-versa. Results support the apparent competition hypothesis. Expanding white-tailed deer appear to be causing mule deer population declines in our 3 study areas.
Robinson, H.S., R.B. Wielgus, H.S. Cooley, Maletzke, B.T., and Cooley S.W. 2008. Cougar aggregative response in a white-tailed deer and mule deer community. Journal of Applied Ecology. (In Prep).
Wielgus R.B., H.S., Robinson, J.C. Gwilliam, and J. Clobert. 2007. Resource competition, predator limitation, and apparent competition in a white-tailed deer, mule deer, and cougar community. Journal of Wildlife Management. (Submitted).
Current Projects
Effects of Hunting on Cougar Population Ecology
Effects of Hunting on Cougar/Human Conflicts
Effects of Hunting on Cougar Prey Selection and Sexual Habitat Segregation
Effects of Sex and Age on Cougar Prey Selection in a Mule Deer and Elk Community
Population Growth and Persistence of Endangered Mountain Caribou in the Selkirk Mountains