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).