A bit larger and chunkier than its here-all-year cousin, the House Finch, a male Cassin’s Finch in the winter sun can really catch your eye. His brilliant rose-red cap, often raised in a small crest like a red-headed Bart Simpson (left), shines unmistakably. His back, breast, flanks, and rump patch show a much paler, pinkish blush set off on a white background. Females and immature males, seriously drab by comparison, sport brown streaks on clean white backgrounds. Many songbirds molt into their adult plumage by their first fall. But male Cassin’s Finches still wear the drab brown-streaked female plumage well into their 2nd year. Yet these 2nd-year males sing much like the older males do, leading to the false impression that both sexes sing with gusto during breeding season. On occasion, yellow- or orange-colored males occur in the wild, perhaps due to diets deficient in carotenoids—the pigments responsible for the reds of both Cassin’s and House Finches.
Cassin’s Finches in Colorado occur throughout the mountains and in much of the southern Colorado pinyon-juniper woodlands. Most birds move to lower elevations such as our area in the fall and head back to higher breeding grounds from mid-March to late May. In the winter, they may visit bird feeders regularly although their occurrence at any given spot varies dramatically from year to year.
Cassin’s Finches feed mostly on seeds, but they also eat evergreen buds, aspen and willow catkins, berries, and insects in warmer months. While they forage primarily on the ground, we watch them in large numbers jockeying for position on nearly all of our feeders as well.
Cassin’s Finches generally do not breed in our area, preferring habitats at altitudes of 8,000 – 11,000 feet. Cassin’s abound in the high country during breeding season, yet very little is known about their breeding activities. A clutch generally contains 4–5, probably hatching in 13–14 days. Both parents feed young in the nest by regurgitating a slurry of the adult’s diet. Presumably both adults also feed fledglings as well. The youngsters apparently remain with parents for some time as family groups and the family departs the breeding site while the fledglings still depend on the adults.
The binomial scientific name of the Cassin’s Finch is Haemorhous cassinii. The genus name (Haemorhous) refers to the red rump patch in Greek—“haem” for “blood” and “orrhos” for “rump”—although this characteristic is much more obvious in their close relative, the House Finch. The common name “finch” derives from the Anglo-Saxon word finc, their name for this bird and an imitation of their call. John Cassin looms large in both the species name (cassinii) and the common name (Cassin’s Finch). A 19th-century Philadelphia ornithologist with a broad knowledge of the birds of the world, Cassin considered this species to be the “greatest bird in the lot” among a collection made by the Pacific Railroad Survey in the southwest mountains in the early 1850s. (Really? They’re pretty birds, to be sure. But the greatest might be more of a reflection on the collection than on the bird itself.) Typically, it was considered bad form for a taxonomist to name a species after himself. But you could cajole any fellow taxonomists who were naming species. At Cassin’s request, Spencer Baird named this striking new finch for his colleague. Cassin’s name graces a number of species in North America—Cassin’s Kingbird, Cassin’s Auklet, Cassin’s Sparrow, Cassin’s Vireo—and even a 17-year cicada. Whether these names reflect his great reputation or his powers of persuasion may ever remain a secret of history.
You can learn more about Cassin’s Finches, including comparisons with the very similar House Finch and Purple Finch, here.