Ecology of the Western Gray Squirrel in South-Central Washington: Progress Report PDF Format - [3.48MB] ACKNOWLEDGEMENTS Funding for this research was provided by grants from the U.S. Fish and Wildlife Service through the State Wildlife Grants and Partnerships for Wildlife Programs, the National Fish and Wildlife Foundation, and contributions from Champion Pacific Corp. (now the Campbell Group) and Boise Cascade Corp. The U.S. Forest Service Pacific Northwest Research Station and the Washington Department of Natural Resources provided in-kind support. We thank the numerous squirrel researchers who provided advice and encouragement at various points of the study, including Andy Cary, Norris Dodd, John Koprowski, Mary Linders, and Todd Wilson. Mary Linders also provided productivity data and animal histories for 1999. Gary Roloff, wildlife biologist with Boise Cascade, and Angela Stringer, wildlife biologist with the Campbell Group, provided key support with the timber industry. We appreciate the collaboration of Ken Warheit for work in the genetics arena and Keith Hobson for work on isotope analysis. This research would not have been possible without the efforts of a dedicated field staff that included Shelly Adams, Catherine Brown, Anna Carlisle, Greg Falxa, Kim Jones, Sara Hansen, Melissa Hill, Cody Massing, Cheri McNeely, Judy Morgan, Lauren Pasniewski, Darina Roediger, Sue Van Leuven, and Joshua Young. Thanks also to the many volunteers who assisted with long days of trapping, and to District Biologist David Anderson for his support of the project from its inception. The able assistance and support from WDFW Regional and Wildlife Area staff was greatly appreciated. Finally, we thank the many private and corporate landowners in Klickitat County including Boise Cascade, the Campbell Group, and SDS Lumber Co., who allowed access to their lands during various stages of this and related research. See also: Surveys for Western Gray Squirrel Nests On Sites Harvested Under Approved Forest Practice Guidelines: Analysis of Nest Use and Operator Compliance

Ecology of the Western Gray Squirrel in South-Central Washington: Progress Report W. Matthew Vander Haegen, Gene R. Orth and Liana M. Aker January 2005 Abstract We studied the ecology of the western gray squirrel (Sciurus griseus) in south-central Washington from 2000-2004, focusing on the parameters necessary to examine population growth and how they may be influenced by natural and human-caused events. We captured 149 individual squirrels during 17 semi-annual trapping session (651 total captures) and marked most with ear tags and radio-collars. Annual survival of adults ranged from 51 to 65% and was similar for males and for females. Mortality for males tended to occur more frequently during late winter and early spring, coinciding with the mating season. Survival of juvenile squirrels from first capture in fall through 1 March ranged from 60 to 86%. Predation was the major cause of mortality for western gray squirrels most years. Notoedric mange was present in the population all years and was most prevalent, and most severe, in winter and early spring. Mortality due to mange ranged from 10 to 40% annually and was the dominant cause of death one year. Most females attempted breeding each year, including yearlings. Litter size averaged 3.3 and ranged from 2-5 (n = 19). The number of young raised to emergence from the natal den (approx. 8 weeks of age) averaged 2.5 (n = 45). Density of squirrels on 3 study sites, as determined from mark-recapture estimates, ranged from 0.1 to 0.26/ha in spring and from 0.17 to 0.43/ha in fall. Home range (95% fixed-kernel) estimates for female western gray squirrels averaged 18.7 ha (9.9 sd, n = 49); 50% core use areas averaged 4.29 ha (2.25 sd, n = 49). Examination of core use area plots revealed little overlap among females within the same year, suggesting exclusive use of these core areas. Females demonstrated strong fidelity to core use areas from year to year although the size of these areas varied among years. Twenty percent of juvenile squirrels dispersed from the study area where they were captured. Dispersal rates for males (3 of 13) and for females (3 of 17) were similar. Mean dispersal distance was 2862 m (213 sd). Mast surveys of Oregon white oak and ponderosa pine revealed wide variation in availability of these foods from year to year, but similar trends between the 2 study sites surveyed. Plans for 2005 include continued demographic monitoring with an emphasis on survival and movements of young after leaving the natal den. Potential timber harvests on 2 of the 3 study sites also may provide an opportunity to examine how females respond to changes in the stand structure of their core areas and home range. Related links: Surveys for Western Gray Squirrel Nests On Sites Harvested Under Approved Forest Practice Guidelines: Analysis of Nest Use and Operator Compliance Gray Squirrel Identification