Snowshoe Hare (Lepus americanus): A Technical Conservation Assessment Prepared for the USDA Forest Service, Rocky Mountain Region, Species Conservation Project July 19, 2006 Ethan Ellsworth1 and Timothy D. Reynolds, Ph.D.2 1Department of Fish and Wildlife Resources, University of Idaho, Moscow, ID 83844 2TREC, Inc., 4276 E 300 North, Rigby, ID 83442 Peer Review Administered by Society for Conservation Biology Ellsworth, E. and T.D. Reynolds. (2006, July 19). Snowshoe Hare (Lepus americanus): a technical conservation assessment. [Online]. USDA Forest Service, Rocky Mountain Region. Available: http://www.fs.fed.us/r2/ projects/scp/assessments/snowshoehare.pdf [date of access]. ACKNOWLEDGMENTS We are indebted to Dennis Murray for providing a wealth of information and to Patricia A. Isaeff for assembling the Envirogram into a crisp display. Gary Patton made a series of important recommendations that significantly improved this manuscript. Oz Garton helped us with our discussion of sensitivity and elasticity, and we are grateful for the encouragement and assistance offered by Steve Abele, Janet Rachlow, Kerry Reese, and Kathy Strickler. AUTHORS’ BIOGRAPHIES Ethan Ellsworth is a PhD. candidate in the Department of Fish and Wildlife Resources at the University of Idaho. For his dissertation research he spent three years in the wilds of northern Idaho near Priest Lake studying snowshoe hare. He has coauthored two hare papers related to using fecal pellets to estimate hare population density, and he has more in the works on hare winter nutrition, food limitation, and energy use. Prior to his study of snowshoe hares, his primary research interests were in avian studies and biogeography. He was part of several bird projects including studies of marbled murrelets, northern goshawks, golden eagles, shrub-steppe birds, and raptors in the Snake River Canyon. He earned his M.S. from Boise State University in the Department of Raptor Biology where he studied juvenile western screech-owl dispersal. Timothy D. Reynolds is President and owner of TREC, Inc., a consulting firm specializing in environmental services and ecological research in Rigby, Idaho. He received a Ph.D. from Idaho State University in 1978 and a M.S. from Illinois State University in 1974. During his career, he has been a Visiting Professor of Biology at Boise State University, Radioecologist for the U.S. Department of Energy, and a Research Ecologist and Director of Operations for the Environmental Science and Research Foundation. He has conducted and coordinated ecological research on birds, mammals, reptiles and ecological aspects of hazardous waste management, and has nearly 50 publications in the technical literature. COVER PHOTO CREDIT Snowshoe hare (Lepus americanus). South Central Service Cooperative: http://www.SCSC.k12.ak.us. LIST OF ERRATA 2 3 SUMMARY OF KEY COMPONENTS FOR CONSERVATION OF SNOWSHOE HARE The population ecology and biology of snowshoe hares (Lepus americanus) are well-studied topics in boreal forests of Canada and Alaska, yet relatively little research has been conducted on hares in the Rocky Mountains. For some wildlife species the lack of regionally specific information might not be particularly important, but in this case it is apparent that critical regional differences exist in ecological conditions and population dynamics between boreal and Rocky Mountain hare populations. The Rocky Mountains are much more heterogeneous in terms of climate, topography, and habitat types when compared to boreal forests, and this has a major impact on hare ecology. Hares in the Rocky Mountains use a broad range of forest types, consume a variety of winter browse species, are preyed upon by a large suite of predators, and likely have a different role in community-level dynamics. Their populations also are smaller and patchier, but apparently more stable. The importance of focused hare research in the Rocky Mountains is further underscored by the recent listing of Canada lynx (Lynx canadensis) as threatened in the contiguous United States under the Endangered Species Act (U.S. Fish and Wildlife Service 2000), and by lynx recovery efforts in Colorado. Canada lynx are specialist hare predators in northern regions, and their livelihood in boreal forests is dependent on a minimum threshold density that is estimated to be > 0.5 hares per ha, or that ranges from 1.1 to 1.8 hares per ha. In the western United States, hare population densities that reach these levels tend to be found in comparatively small and medium-size patches of suitable habitat; expansive areas that support abundant hare populations are relatively uncommon. It is not clear whether the size of western hare populations have changed during historic times because there are no long-term data sets of hare populations in southern areas. However, reduced populations of lynx in the West could indicate that their main prey base, snowshoe hares, has declined as well. Furthermore, fire suppression has contributed to a decline in the abundance of young lodgepole pine (Pinus contorta) stands, a particularly important habitat for snowshoe hares in at least some western mountains. In this paper, we emphasize the importance of snowshoe hare conservation in light of Canada lynx requirements and provide management recommendations that could enhance hare habitat quality. In particular, we provide specific management recommendations for two of the most important habitat types for hares in the Rocky Mountains, lodgepole pine and Engelmann spruce - subalpine fir forests Picea( engelmannii - Abies concolor). Although these species are common associates in subalpine environments, a distinction is made between them because some important differences exist in the dynamics of the ecological relationship with hares. Most importantly, patterns of hare abundance fluctuate in distinctly different ways in spruce-fir and lodgepole pine forests. Overall, hares probably reach a higher density in young lodgepole pine forests, but they are probably more stable over longer time periods in spruce-fir forests. Hares are abundant in young lodgepole pine forests with a high stem density because cover conditions are good and lodgepole pine is a highly nutritious conifer. However, optimum structural conditions (i.e., dense understory cover) are typically short-lived. As lodgepole forests mature, they self-prune their lower branches and simply do not contain enough understory cover to provide refuge or forage for a high density of hares. In lodgepole pine forests, our primary management recommendation to maintain dense hare populations is to promote the growth of young regenerating stands (via fire in particular). Conversely, mature spruce and fir tend to retain their crown at low levels, providing food and cover for hares. Consequently, there are fewer apparent benefits to disturbance in spruce-fir forests. In spruce-fir forests, we recommend that managers focus on preserving large blocks of interconnected habitat. 2 3 TABLE OF CONTENTS ACKNOWLEDGMENTS ..............................................................................................................................................2 AUTHORS’ BIOGRAPHIES .........................................................................................................................................2 COVER PHOTO CREDIT .............................................................................................................................................2 SUMMARY OF KEY COMPONENTS FOR CONSERVATION OF SNOWSHOE HARE ........................................3 LIST OF TABLES AND FIGURES ...............................................................................................................................6 INTRODUCTION ..........................................................................................................................................................7 Goal............................................................................................................................................................................7 Scope..........................................................................................................................................................................8 Treatment of Uncertainty ...........................................................................................................................................8 Publication of Assessment on the World Wide Web ..................................................................................................8 Peer Review ...............................................................................................................................................................8 MANAGEMENT STATUS AND NATURAL HISTORY .............................................................................................8 Management Status ....................................................................................................................................................8 Existing Regulatory Mechanisms, Management Plans, Conservation Strategies......................................................9 Biology and Ecology..................................................................................................................................................9 Classification .........................................................................................................................................................9 General species description.................................................................................................................................10