Publication Date

5-2009

Date of Final Oral Examination (Defense)

4-7-2009

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Biology

Department

Biology

Supervisory Committee Chair

James C. Munger, Ph.D.

Supervisory Committee Member

Eric Yensen, Ph.D.

Supervisory Committee Member

Alfred M. Dufty, Jr., Ph.D.

Abstract

Populations of the southern Idaho ground squirrel (Spermophilus endemicus; SIDGS), a federally listed candidate species, have declined in the last 30 years mainly because of habitat degredation, loss, and fragmentation. As a management tool, translocation is commonly used to augment, establish, or re-establish wildlife populations, although translocation has historically not been the most successful conservation strategy for species that are threatened or endangered animals as a result of habitat loss. I employed various techniques to improve translocation success of southern Idaho ground squirrels. To establish new populations, I relocated SIDGS to areas within their native range not already occupied by other individuals of that species. In 2006, I trapped 104 squirrels from the Van Deussen Ranch near Emmett, ID and 212 from the Scotch Pines Golf Course in Payette, ID and translocated them to Little Willow Flat on the Soulen Ranch, approximately 40 km north of Emmett, ID. In 2007, I trapped 170 squirrels from the Van Deussen Ranch and translocated those individuals to another area on the Soulen Ranch, approximately eight km southeast of Midvale, ID. I examined the influence of age, sex, release type, and habitat quality on translocation success. Of the 486 southern Idaho ground squirrels that I trapped and translocated, 112 were fitted with radio collars and monitored for post-release movement and survival. Adult survival to estivation was 45% in 2006 and 55% in 2007. Only 12% of juveniles (4 of 34) survived to estivation (2007 only). An exact logistic regression model showed that age and the interaction of age by release type were significantly associated with survival (p < 0.05) in 2007, because more adults survived than juveniles and more hard-released adults survived than soft-released adults. All squirrels, regardless of where they were released, settled in high-quality habitat. Although some factors and interactions correlated with an increase in survival until estivation, over-winter survival was low, at best, so these translocations failed to establish new populations at or near the release site.

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