As the winter feeding season approaches, a perennial identification challenge looms: Purple Finch versus House Finch.
The two species are close relatives. Both are sparrow-sized and have stout bills. Adult males show lots of reddish color, while females and immatures are brown and streaky. Field guides tend to stress details of color for identification, but color is notoriously variable.
For example, most males can be distinguished by the overall shade of red — House Finch tends to be more orange, while Purple Finch appears more pink-purple (wine-red) — but it’s not unusual to see a finch with an ambiguous reddish color. Male House Finches can occasionally be wine-red, and, rarely, male Purple Finches can be orange-red.
Females can almost always be distinguished by the contrasting dark and light markings on Purple Finch and the muted gray brown coloration on House Finch. Even in females, though, the least boldly marked Purple Finch can look similar to the most contrasting House Finch.
A more reliable way to distinguish the species, regardless of color or sex, is by shape and proportion. The best details to focus on are at opposite ends of the bird: head shape and tail shape. Look for a slight peak or triangular crest on the head of Purple Finch and a smoothly rounded head on House Finch. Purple Finch also has a shorter tail with a distinct notch at the tip, while House Finch has a longer tail whose feathers are all about the same length.
These details and others add up to an overall “broad-shouldered” impression for Purple Finch. It has a short neck, a large head, a short tail, and short legs, and appears stockier than House Finch, which has a relatively small head and long tail and looks more slender. These impressions can be helpful, but it’s always best to focus on the head and tail.
Color remains a valuable clue, easy to see and assess in an instant, and fairly reliable, but you should be cautious of using color alone. If you make a habit of checking the shape of the head and tail each time you see a finch, you will soon develop an intuitive sense of the unique shape of each species.
This article from David Sibley’s “ID Toolkit” column appeared in the November/December 2016 issue of BirdWatching.
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