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An analysis of monthly home range size in the critically endangered California Condor Gymnogyps californianus

March 10, 2014

Condors and vultures comprise the only group of terrestrial vertebrates in the world that are obligate scavengers, and these species move widely to locate ephemeral, unpredictable, and patchily-distributed food resources. In this study, we used high-resolution GPS location data to quantify monthly home range size of the critically endangered California Condor Gymnogyps californianus throughout the annual cycle in California. We assessed whether individual-level characteristics (age, sex and breeding status) and factors related to endangered species recovery program efforts (rearing method, release site) were linked to variation in monthly home range size. We found that monthly home range size varied across the annual cycle, with the largest monthly home ranges observed during late summer and early fall (July–October), a pattern that may be linked to seasonal changes in thermals that facilitate movement. Monthly home ranges of adults were significantly larger than those of immatures, but males and females used monthly home ranges of similar size throughout the year and breeding adults did not differ from non-breeding adults in their average monthly home range size. Individuals from each of three release sites differed significantly in the size of their monthly home ranges, and no differences in monthly home range size were detected between condors reared under captive conditions relative to those reared in the wild. Our study provides an important foundation for understanding the movement ecology of the California Condor and it highlights the importance of seasonal variation in space use for effective conservation planning for this critically endangered species.

Publication Year 2014
Title An analysis of monthly home range size in the critically endangered California Condor Gymnogyps californianus
DOI 10.1017/S0959270913000592
Authors James W. Rivers, Matthew J. Johnson, Susan M. Haig, Carl J. Schwarz, Joseph Burnett, Joseph Brandt, Daniel George, Jesse Grantham
Publication Type Article
Publication Subtype Journal Article
Series Title Bird Conservation International
Index ID 70134834
Record Source USGS Publications Warehouse
USGS Organization Forest and Rangeland Ecosystem Science Center