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Interannual consistency of migration phenology is season- and breeding region-specific in North American Golden Eagles

July 20, 2022

Interannual consistency (an indicator of the strength of adjustments) in migration phenology of Golden Eagles (Aquila chrysaetos) in North America is most strongly associated with the breeding region, the season, and with late-season temperature on breeding and wintering grounds. Consistency was greatest in boreal spring migration and the breeding regions of eastern Canada. Using multi-year GPS tracks of 83 adults breeding in 3 spatially distant regions (Alaska, northeast Canada, and southeast Canada), we quantified the interannual consistency of migration phenology and wintering latitude within and among individuals tracked across multiple years and the repeatability (r) by breeding regions and seasons. By comparing regions and seasons, we found that consistency was highest (r > 0.85) for boreal spring migration in eastern Canada while Alaska had the lowest value (r < 0.15). Because seasonal consistency of migration phenology was only detected in eastern Canada, we conclude that seasonal features are not a primary constraint. While regional differences in consistency were not related to differences in migratory distances, they could be the result of genetic or habitat differences. We also found that temperatures warmer than the decadal average at the region of departure delayed the start of boreal spring migration by ~10 days and advanced boreal autumn migration by ~20 days. These results suggest that warmer temperatures would reduce residence time on breeding grounds, contrary to expectations and trends found in other studies. Wide variations in migratory strategies across a species distribution can add to the list of challenges for conservation but may give migrants the capacity to acclimate to environmental changes.

Publication Year 2022
Title Interannual consistency of migration phenology is season- and breeding region-specific in North American Golden Eagles
DOI 10.1093/ornithology/ukac029
Authors Laurie D Maynard, Jean-François Therrien, Jérôme Lemaître, Travis L. Booms, Tricia A. Miller, Todd E. Katzner, Scott Somershoe, Jeff Cooper, Robert Sargent, Nicolas Lecomte
Publication Type Article
Publication Subtype Journal Article
Series Title Ornithology
Index ID 70238636
Record Source USGS Publications Warehouse
USGS Organization Forest and Rangeland Ecosystem Science Center