Sampling
We collected blood (N=178) and tissue (N=160) samples from live hummingbirds and carcasses for a total of 338 unique hummingbirds across the historical Central and Southern California range and the expanded ranges in Northern California, Washington, Arizona, and Nevada (Fig. 1). Hummingbirds were trapped using previously published methods by a federally permitted hummingbird bander (Tell; US Geological Survey Bird Banding Laboratory Permit #23947). When possible, female birds were examined for evidence of an enlarged oviduct or the presence of an egg for inclusion in the study. Blood was collected (20-30µl, less than 1% body weight) via a toenail clip (N=166; ), and placed in Queen’s lysis buffer , or blood was collected on an FTA card (N=12). All collection methods were approved by the University of California, Davis IACUC (F#20355). In addition to samples taken from live birds in the field, we added specimens from the Burke Museum collection at the University of Washington and carcasses from wildlife centers for nestlings or fledglings that did not survive the rehabilitation process (see Supplemental file, ANHU_metadata4ms.xlsx, for sample details). For native range samples, we used females and males collected between February and August when many of the sampled birds showed evidence of breeding, however due to low sample availability we used females and males collected throughout the year in the expanded regions. Sampling outside of the breeding season, however, did not appear to affect our results (see Results).