Bird of the Month: White-throated Sparrow
Written by Andy McCormick
Andy McCormick, Volunteer and Former Board President of Eastside Audubon
The White-throated Sparrow is being seen more often during Washington winters and birders have two color morphs to appreciate.
The White-throated Sparrow has no subspecies but has two distinct color morphs with each half of the sparrows white-striped (WS) or tan-striped (TS) on the head. The morphs provide a challenge for birders and a focus for researchers. The WS morph is similar to the White-crowned Sparrow with sharply defined black and white head stripes, but in addition the White-throated Sparrow has a bright yellow spot in front of the eye. The White-throated has a dark bill and is browner than the yellow-billed and mostly gray, White-crowned Sparrow. In both WS and TS morphs the White-throated Sparrow’s white throat is well-defined and usually marked off by thin black malar stripes. The TS morph is scruffier looking with tan stripes abutting lateral black stripes on the head and the yellow supraloral spot is duller (Alderfer).
OPPOSITES ATTRACT
The two color morphs of the White-throated Sparrow are equally represented between the sexes and in the overall population of this species. This balance is maintained by “negative assortive (disassortative) mating – each morph mates with its opposite” (Fall and Kopachena). That is, WS sparrows seek to mate with their opposite color morph TS birds, and TS birds do the same.
What has fascinated researchers is that the morphs are also characterized by behavior differences which seem to balance the mating pairs. The WS males are more aggressive, sing more often, and are more likely to engage in extra-pair copulations. “TS birds of both sexes provide more parental care then WS birds” (Fall and Kopachena). These morph-related behaviors have made the White-throated Sparrow an attractive subject for studies of genetic and endocrine functions and sex chromosome evolution.
White-throated Sparrow
Scientific Name: Zonotrichia albicollis
Length: 6.75”
Wingspan: 9”
Weight: 0.91 oz (26g)
AOU Alpha Code: WTSP
DISTRIBUTION AND MIGRATION
The White-throated Sparrow breeds throughout the boreal and mixed woodland forests across Canada and the north central and eastern United States but does not breed in Washington. Since the 1940s it has expanded both its breeding range and winter range in central and southwest British Columbia (Wahl, et al).
Typically fall migration begins in late September and peaks about mid-October with most White-throated Sparrows moving to the southeastern United States. Wintering populations in small numbers are found from southwest British Columbia south through Oregon and western California. Fall migrating birds from this population are likely to be the source of increased sightings of White-throated Sparrows in Western Washington in winter (Fall and Kopachena). During the winter of 2020-2021 two White-throated Sparrows spent about five months in Marymoor Park in Redmond, WA, and 2019 one was found at Newcastle Beach Park in Bellevue.
ONE OF THE ZONOS
The White-throated Sparrow shares the genus Zonotrichia, Greek for banded thrush from zone, a belt, and trichas, a song-thrush. The reference is to the bands on the head of birds in this genus, which include White-crowned Sparrow (Z. leucophrys), Golden-crowned Sparrow (Z. atricapilla), and Harris Sparrow (Z. querula). The species epithet albicollis, is from the Latin albus, white, and collum, neck, in reference to the bird’s white throat. Interestingly “sparrow” once referred to any small bird and is derived from the Anglo-Saxon spearwa, to flutter (Holloway). In winter the White-throated Sparrows will often join flocks of White-crowned and Golden-crowned Sparrows.
BREEDING AND CONSERVATION
The males arrive on the breeding grounds before the females, but it is the female that builds an open cup nest on the ground or in a low shrub. The nest of grass, twigs, and weeds is lined with small roots and animal hair. Usually, four or five eggs are deposited and are incubated by the female only (Kaufman). Both parents feed the nestlings and young leave the nest in eight or nine days, but continue to be tended to by the parents for about two more weeks.
The White-throated Sparrow is a common bird over North America and its population is stable at between 10-20 million pairs for the total North American population (Fall and Kopachena). There are no management programs in place for this species. Photos, recordings, and video of White-throated Sparrows can be found at the Macaulay Library.
Photo credit Nicole Beaulac and Andy McCormick. References available upon request from amccormick@eastsideaudubon.org.