Bird of the Month: Cassin’s Finch
Written by Andy McCormick
Andy McCormick, Volunteer and Former Board President of Eastside Audubon
One of three North American rose finches, Cassin’s Finch abides in high elevation coniferous forests in the western mountains.
The distinction among North America’s three rose finches can be subtle. Cassin’s Finch is colored with a pink wash on the face, chest, and streaked back. The fore-crown is a contrasting brighter red. Among the males of the three North American rose finches, Cassin’s Finch has the least amount of streaking on the belly, and it is the only one with fine streaking on the undertail coverts. Its bill is slightly longer than that of the Purple Finch and House Finch.
The upper parts of female and immature male Cassin’s Finches are heavily streaked in brown. The chest and belly are white with fine, crisp streaking. The young males retain this streaked appearance for a year but will sing as adult males. The song is a bubbly warble similar to Purple Finch, however, its flight call is the best way to distinguish Cassin’s Finch. It is described as kee-up or tee-dee-yip (Alderfer), or widee-ooli (Sibley). Photos, videos, and vocalizations of Cassin’s Finch can be viewed at The Macaulay Library.
North America’s rose finches are grouped in the genus Haemorhous, from the Greek haema, blood and orrhos, rump, referring to the red color of these birds (Helm). Cassin’s Finch is named for John Cassin (1813-1869), a Philadelphia ornithologist. Of the three species, Cassin’s Finch is evolutionary closest to Purple Finch (H. purpureus), and both species are more distant from House Finch (H. mexicanus) than they are from each other. Finch as a bird name is derived from the Anglo-Saxon finc, their name for this bird (Holloway).
Cassin’s Finch
Scientific Name: Haemorhous cassinii
Length: 6”
Wingspan: 11.5”
Weight: 0.91 oz (26 g)
AOU Alpha Code: CAFI
HIGH ELEVATION BREEDER
Cassin’s Finches breed almost exclusively in conifers. In Washington this would include Douglas fir, Engleman spruce, Ponderosa pine among other cone-bearing trees. Both the male and female build a cup nest of twigs and grass stems at a height between 15 and 60 feet above the ground and well out on a horizontal branch. The birds may line the nest with fine plant fibers, animal hair, and feathers. There is little systematic research about the nesting cycle of Cassin’s Finch, but incubation is estimated to take about 12 days. There is also no data on the time to fledging, but the young remain as part of a family group, which leaves the breeding area as soon as the young fledge (Hahn).
DISTRIBUTION AND MANAGEMENT
The breeding range of Cassin’s Finch can be thought of as encompassing the mountains of western North America including the Rockies and several coast ranges. They are known to nest from south-central British Columbia along the eastern slope of the Cascade Range through Washington and Oregon and through the Siskiyou and Klamath mountains of Oregon, and in the Sierra Nevada and coastal ranges of California. High elevation areas in Montana, Idaho, Utah, and Colorado also provide breeding habitat for this finch. Cassin’s Finches are common within their range and there is no evidence that the population is declining and there are no conservation measures in place.
In winter, Cassin’s Finch is a partial migrant. Some flocks leave the breeding area completely and winter in the southwestern United States and farther south into the mountains of central Mexico. Those that remain behind may move within the wider breeding range or to lower elevation.
EVOLUTION
Graphical abstract of the Finch evolution from Science Direct
House Finch (H. mexicanus) is thought to be a direct descendent of a so-far unidentified ancestor. During a period from 14 million to 9 million years ago, a sister species of House Finch developed from the same ancestor and co-existed with House Finch. This sister species itself evolved between 7 million and 3 million years ago during which time Cassin’s and Purple Finches evolved from it. The sister eventually became extinct leaving behind its descendants Purple Finch (H. purpureus) and Cassin’s Finch (H. cassinii) as separate species. Purple Finch may still be in a period of continued evolution as differences are now recognized between the western and eastern subspecies of Purple Finch.
Photo credit: Robin Agarwal / Flickr (CC BY-NC 2.0)
References available upon request from amccormick@eastsideaudubon.org.