Monitoring through community science: Anna's hummingbird winter range expansion into Idaho

Abstract

Increased urbanization and supplementary feeding are implicated in driving the expansion of the range of the Anna's Hummingbird (Calypte anna). In many areas this range expansion has been well described, but the recent expansion of the northeastern limit of the nonbreeding distribution, in winter in Idaho, has not yet been summarized. Using data from the Idaho Bird Records Committee database and www.eBird.org from 1976 through 2020, we collated records for Idaho and supplemented them with data from a community-science program of monitoring by homeowners. Our additional effort to solicit records from the community shows that database records and feeder observations alone underestimate the number of individuals present in the state. Through banding and color-marking of 58 individual hummingbirds at private residences, we documented six instances of Anna's Hummingbirds returning to a site in successive winters, found a roughly even sex ratio, and found a ratio ofadults to juveniles of about 3:1. Anna's Hummingbird may now be a sparse year-round resident in parts of Idaho.