Meeting Abstract

P3-93    Using GPS PinPoint Backpacks to Document Facultative Altitudinal Migration Malisch, J*; Hawkins, C; Iverson, A; Hahn, TP; St Mary's County Health Department; University of California, Davis; University of California, Davis; University of California, Davis jlmalisch@smcm.edu

Facultative Altitudinal Migration (FAM), a temporary relocation down an elevation gradient to avoid adverse climatic conditions, allows mountain-breeding birds to cope effectively with extreme environmental challenges. This behavior is difficult to predict and therefore a challenge to study. While previous FAM events were captured within a population of mountain white-crowned sparrows at Tioga Pass Meadow, Mono County, CA (~3000 m elev.), data collection pertaining to these events has been constrained by available technology, limited to documenting presence/absence from the meadow and manually tracking a subset of individual sparrows. Previous research has indicated that some WCSP migrate down to the Mono Basin, a change in elevation of about 1000m. With new lightweight GPS PinPoint Backpacks from Lotek, we were able to detail FAM behavior during a late-spring snowstorm (May 21, 2021), including tracking moving individuals to refuge sites not accessible for hand-held radio telemetry at this time of year. During the storm, 4 of 6 WCSPs exhibited FAM behavior and left their Tioga Pass Meadow territories and 2 remained in the vicinity of the meadow. Surprisingly, during this FAM event, none of the WCSPs sought refuge in the Mono Basin, but instead flew west into Yosemite National Park, the first documentation of such behavior in this well-studied population of sparrows. We also quantified body condition and plasma levels of testosterone, corticosterone and corticosteroid binding globulin. Future analyses will determine whether hormone levels predict FAM duration as seen in previous studies.