Clark's Nutcrackers (Nucifraga columbiana) are important seed dispersers for at least 10 species of conifer in western North America and are obligate mutualists for the subalpine tree, whitebark pine ( Pinus albicaulis). Despite the important role they play in forest regeneration, space use by nutcrackers has not been formally studied. Several hypotheses exist to explain their year-round space use patterns. I tested one hypothesis that Clark's Nutcrackers migrate altitudinally between summer and autumn in one population in the Cascade Range, Washington. In 2006 and 2007, I compared seasonal differences in summer and autumn space use by 26 radio tagged nutcrackers. Five nutcrackers remained as year-round residents on their home ranges and 21 emigrated from the study area in summer. Among residents I found summer and autumn ranges overlapped and summer ranges were contained within autumn ranges. Residents increased their use of low elevation habitats as autumn progressed but rather than migrating from summer ranges, they used low elevation forests only for seed harvesting. High elevation portions of the summer range were used for all other activities including seed storage even though this required residents to transport seeds from harvest trees up to 29 km in distance and 1007 m in elevation. I was unable to test hypotheses regarding space use by emigrants. However, my results suggest that emigrants in this study did not migrate altitudinally because they did not show a seasonal trend in movements either upslope or downslope.
|Advisor:||Sullivan, Kimberly A.|
|Commitee:||Gese, Eric M., Haefner, James W.|
|School:||Utah State University|
|School Location:||United States -- Utah|
|Source:||MAI 47/06M, Masters Abstracts International|
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