Black-tailed Jackrabbits Lepus Californicus Research Articles

A Review of the Ongoing Decline of the White-Tailed Jackrabbit

The distribution and abundance of the white-tailed jackrabbit Lepus townsendii have declined significantly since 1950, continuing a trend that began in some regions of its range in the late 1800s. We reviewed museum records and the literature to evaluate the status of the white-tailed jackrabbit in each state and province in its historical range and evaluated possible reasons for its decline. Our evaluation revealed its extirpation or decline throughout much of its range, but its legal or conservation status does generally not reflect this precarious status. We note its extirpation in Missouri, Kansas and Oklahoma, and potential extirpation in British Columbia, Oregon, Illinois, and Wisconsin. We classified the white-tailed jackrabbit to be broadly extirpated in Iowa, Minnesota, Washington, Nebraska and California, and declining with local extirpations in Wyoming, Nevada, Utah, Colorado, New Mexico, and South Dakota. We consider it to be a relict in Ontario, and possibly declining in Alberta, Saskatchewan, North Dakota, Idaho, and Montana. We consider only Manitoba to have a possibly stable population. Determining the reasons for the species' reduced distribution is difficult, as the decline appears to be due to multiple factors, none of which provide a universal explanation. We dismissed road kills, recreational hunting, disease and parasites, and competition with black-tailed jackrabbits Lepus californicus as causes of the widespread population declines and extirpations. We concluded that habitat alterations and climate change are overriding factors, and that past depredation measures and increased predator populations have likely contributed to the decline. These hypotheses require further testing. We recommend more research on the distribution, abundance, ecology, and population dynamics of white-tailed jackrabbits, and management that includes a frank appraisal of the species' status, the potential for grassland restoration, and programs to reintroduce populations into prairie preserves and restored grasslands.

A Review of the Ongoing Decline of the White-Tailed Jackrabbit

Abstract The distribution and abundance of the white-tailed jackrabbit Lepus townsendii have declined significantly since 1950, continuing a trend that began in some regions of its range in the late 1800s. We reviewed museum records and the literature to evaluate the status of the white-tailed jackrabbit in each state and province in its historical range and evaluated possible reasons for its decline. Our evaluation revealed its extirpation or decline throughout much of its range, but its legal or conservation status does generally not reflect this precarious status. We note its extirpation in Missouri, Kansas and Oklahoma, and potential extirpation in British Columbia, Oregon, Illinois, and Wisconsin. We classified the white-tailed jackrabbit to be broadly extirpated in Iowa, Minnesota, Washington, Nebraska and California, and declining with local extirpations in Wyoming, Nevada, Utah, Colorado, New Mexico, and South Dakota. We consider it to be a relict in Ontario, and possibly declining in Alberta, Saskatchewan, North Dakota, Idaho, and Montana. We consider only Manitoba to have a possibly stable population. Determining the reasons for the species' reduced distribution is difficult, as the decline appears to be due to multiple factors, none of which provide a universal explanation. We dismissed road kills, recreational hunting, disease and parasites, and competition with black-tailed jackrabbits Lepus californicus as causes of the widespread population declines and extirpations. We concluded that habitat alterations and climate change are overriding factors, and that past depredation measures and increased predator populations have likely contributed to the decline. These hypotheses require further testing. We recommend more research on the distribution, abundance, ecology, and population dynamics of white-tailed jackrabbits, and management that includes a frank appraisal of the species' status, the potential for grassland restoration, and programs to reintroduce populations into prairie preserves and restored grasslands.

Seasonal Variation in the Diet of Great Horned Owls (Bubo virginianus) on Shortgrass Prairie

-We collected and analyzed pellets from known roosts of great horned owls (Bubo virginianus) on shortgrass prairie in N-central Colorado between 1992 and 1994 to examine seasonal trends in owl diets. We also compared the species composition of small rodents in owl diets to the relative abundances of rodents on the study area. In all seasons, lagomorphs (desert cottontails Sylvilagus audubonii, black-tailed jackrabbits Lepus californicus, white-tailed jackrabbits Lepus townsendii) comprised most of the diet biomass. Northern pocket gophers (Thomomys talpoides) were also preyed upon in all seasons, with the highest percentage consumed in spring. Most of the individual prey items taken were rodents, primarily deer mice (Peromyscus maniculatus). Comparisons of diet composition with measures of rodent abundance suggested that owls foraged over a relatively restricted part of our study area, especially in winter. Most prey apparently were taken from roadsides, buildings and an adjacent four-wing saltbush (Atriplex canescens) floodplain, where rodent densities remained relatively higher in all seasons than in the surrounding vegetation. We speculate that the preferential use of these foraging habitats may reflect the availability of suitable hunting perches on the site.