Birds
White-Throated Sparrow
Zonotrichia albicollis · also called white-throated sparrows
Two white-throated sparrows, one boldly white-striped and one more subtly tan-striped, forage together as a mated pair, an outcome so consistent across the species that researchers have traced the entire pattern back to a single chromosomal difference between the two permanent colour forms.
Overview
The white-throated sparrow, Zonotrichia albicollis, is a forest songbird that breeds across Canada and the northeastern United States before wintering across much of the eastern and southern United States. Its two permanent colour morphs and unusual opposite-morph mating system make it one of the more genetically and behaviourally fascinating sparrows studied by ornithologists.
A mating system written into the chromosomes
Rather than choosing a mate based on typical courtship preferences alone, the white-throated sparrow’s pairing pattern traces back to genetics itself, with a chromosomal difference between its two colour forms driving one of the more unusual mating systems documented in any songbird.
Status
Least Concern — widespread and stable across suitable forest breeding habitat and its broad wintering range across North America.
White-Throated Sparrow: common questions
Why does the white-throated sparrow almost always pair with the opposite colour morph?
A white-throated sparrow's two permanent colour morphs, white-striped and tan-striped, are tied to a chromosomal difference between the forms, and pairing overwhelmingly occurs between opposite morphs, creating a genuinely unusual four-way mating system in which nearly every successful pair combines one white-striped and one tan-striped bird regardless of sex.
What does the white-throated sparrow's song sound like?
A white-throated sparrow produces a clear, whistled song often rendered in English as "oh sweet Canada, Canada, Canada," a phrase memorable and recognisable enough to make the species' song one of the more frequently described bird calls in eastern North America.
How can you identify a white-throated sparrow?
The white-throated sparrow displays a bright white throat patch along with a small yellow spot just above the eye, distinctive features that, combined with either the white-striped or tan-striped head pattern, help separate it from several similar-looking sparrow species.
Where does the white-throated sparrow live?
The white-throated sparrow breeds in coniferous and mixed forest habitat across Canada and the northeastern United States, then migrates to winter across much of the eastern and southern United States.