This is a very localized resident in the Sonoran Desert region from south-central Arizona to northern Sinaloa, Mexico. It was one of the last United States birds to be described. Bendire collected the first specimens near Tucson in 1872. The species disappeared from the area by 1886 but was eventually rediscovered there in 1936. However, that site was destroyed by a housing development in 1965. It prefers thornbush with mixed bunch-grasses, a habitat threatened by grazing.
This species was formerly merged with Aimophila, but now placed in the genus Peucaea on the basis of genetic as well as morphological and vocal data (51st supplement to the AOU Checklist). In fact this bird was originally named by Coues (1873) as Peucaea carpalis ("Bay-winged Summer Finch").
Geographic variation is slight and no subspecies are currently recognized.
Digiscoped with Panasonic DMC-LZ5 | Nikon FieldScope III | 30XWA | hand-held (no adapter)