Flight Lines: Purple finch, the one 'supposed' to be here
February, 1980, marked a moment of some significance among the state's birders. This was a milestone. In Bismarck, North Dakota, the first official sighting of a house finch was recorded. Two months later Cass County got one too; on April 6, to be exact.
The occasion was not unexpected, however. House finches, you see, were steadily and inexorably marching across the continent from both coasts. Originally a western species, house finches had been introduced to the east during the 1970s. So from both directions, the heartland filled in. It was only a matter of time.
However, there is a distinct possibility the bird was here even before the date above. Why? Because house finches closely resemble another reddish finch which had historically been the only one to ply the skies and feeders of North Dakota, the purple finch (Carpodacus purpureus).
Indeed, of the three red-colored Carpodacus finches native to the U. S., the purple finch was the only one "supposed" to occur here. At least that's what all the range maps in the field guides showed at the time. So it's not out of the question the first instances of house finch appearances were dismissed as merely purple finches.
The differences between these two species can be subtle. But once a person has seen a few, they're not difficult to differentiate.
By now we are all familiar with house finches. They are permanent residents in and around town, and often nest in decorative wreaths for whatever reason. Even in winter, dusty-brown streaked females and equally brown-streaked males (but with bright red highlights about the head and upper breast) are common.
Come fall though, purple finches usually arrive to confuse us. Male purple finches are distinct from their house finch counterparts by being unstreaked and having a deep cabernet-red appearance on its upper parts, even onto its back and wings. Roger Tory Peterson once described the purple finch as, "a sparrow dipped in raspberry juice."
The females of the two species might be even easier to discern. While an even dinginess permeates house finch females, a female purple finch is strongly brown-streaked on a white breast, with a bold whitish "eyebrow." Once a person studies the face of a female purple finch, he will not confuse it with a house finch again.
Purple finches nest in a broad swath of southern Canada, the far northern U.S., and along the spine of the Sierras in the west. Breeding grounds are abandoned in fall when purple finches usually invade the entire eastern U.S. down to the Gulf Coast. In other words, look for them now.
Being seed specialists, these birds can be quite common at feeding stations in winter, especially those offering black oil sunflowers. But for whatever reason, purple finches can be iffy in our area. Four times in the last 20 years the Fargo-Moorhead Christmas Bird Count has failed to find purple finches. Plus nine individuals were the most counted during any one count day.
I would guess the reason for low purple finch numbers in Cass County has more to do with habitat than anything. Since the birds are mainly conifer specialists, I can see where they'd mostly pass us up. There might also be a competitive element to this. In one study, house finches essentially evicted purple finches in 95 percent of encounters.
Away from feeders, purple finches can be tough to see as often they are feeding high up in trees. The good news is the birds are rather noisy, which usually gives their presence away even in winter. Pete Dunne describes the purple finch song as a "hurried, mumbled, run-on warble that is sweeter and less histrionic than the house finch." Even in flight a distinctive flat "pik" can usually be heard.
One of my source books said house finches are "hard to miss." I agree. But when the same book said "easy to see" of the purple finch, I winced. In Cass County at least, this is not always the case.