European Goldfinch, fall 2010
This European Goldfinch (Carduelis carduelis) was captured and, with the permission of the U.S.G.S. Bird Banding Lab, banded, by the Rouge River Bird Observatory on 14 September 2010.
This species is not native to North America, and is a popular cage bird. Sightings across the eastern U.S. in particular are common, and this is the second we have had in Dearborn. The first, found on 11 January 2003, spawned a project documenting sightings in the western Great Lakes region. While this bird, like most in southeast Michigan, is most likely escaped or released from captivity (read on for evidence), European Goldfinches have become established as a breeding species in northern Illinois and southern Wisconsin, and perhaps elsewhere. This was apparently the result of repeated releases by an importer near Chicago. You can read more about this in a paper I published in 2008.
The bird was an adult, based on a fully-ossified skull 1. If the bird were a juvenile, the skull would not be completely ossified in this species until at least November.
It was a male, based on several plumage characteristics. First was the uniform deep black color of the wing feathers (click for wing photo), including the wing coverts. In females, the coverts would be duller black, and/or have brown edges. The wing and tail feathers were all fresh, with no indication of cage-wear. European Goldfinches molt earlier in the season than American Goldfinches, and adults would be nearing completion of their fall (or prebasic) molt at this time. This bird was still molting many body feathers, but had nearly completed replacement of the wing feathers (only the last two secondaries, also known as tertials, were incoming).
A second characteristic was the black coloration of the feathers bordering the upper bill and nasal area (click for close up of this feature), which in females is brownish. This last feature in particular is very well illustrated on this web site.
A final clue was the extent of the red mask, which in males covers the upper rear border of the eye. The head feathers were molting, with many feathers just coming in — these appear as the whitish “rice grains” interspersed in the feathers in the photo at right. Thus the full extent of the mask may be a bit broader than it appears at this time. This feature is compared side-by-side in this photograph, and also shows the different-colored nasal feathers of each sex.
Generally, males also have deep crimson-colored masks, and females have more orange-red masks. Red, orange, and yellow plumage coloration in birds is dietary in origin. Birds cannot manufacture these colors and must ingest certain carotenoid pigments in order to produce the “right” colors. A diet insufficient in proper carotenoids can result in what is normally red plumage being orange or yellow (some examples of this may be found on our “Odd Plumages” page). The masks of European Goldfinches are comprised of four different carotenoid pigments.
Inexperienced cage bird owners (such as the ones who might intentionally release their birds or are careless enough to allow them to escape!) may feed their birds a monotonous, poor diet which could account for incoming feathers coming in yellow. Once on the loose, a European Goldfinch in this area finds a large variety of appropriate foods — favorite foods of this species in Europe and Asia include knapweeds (Centaurea spp.), burdocks (Arctium spp.), and teasel (Dipsacus spp.), all established non-native species here. This is a very hardy species, able to survive cold winters easily, and one which will visit bird feeders readily.
There are at least twelve recognized subspecies of European Goldfinch in Europe and Asia, which vary in coloration and size. I am not suggesting this bird is a wild vagrant, but do know that more than one subspecies are both wild caught and captive-bred and imported into the U.S. In addition, there are seven or more color forms bred by cage bird fanciers. Thus, the mask coloration may be not be an indication of poor diet (although I think it is the most likely explanation), but merely some variation on the nominate subspecies.
Cramp, S., and C. M. Perrins. 1994. Handbook of the Birds of Europe, the Middle East and North Africa: The Birds of the Western Palearctic. Vol. 8. Crows to Finches. Oxford Univ, Press, Oxford, U.K.
Jenni, L. and R. Winkler. 1994. Moult and Ageing of European Passerines. Academic Press, London and San Diego.
Lopez, G., J. Figuerola, and R. Soriguer. 2008. Carotenoid-based masks in the European Goldfinch Carduelis carduelis reflect different information in males and females. Ardea 96:233-242.
Please note: Although RRBO is ceasing operations, I am still gathering European Goldfinch data! Please continue to follow instructions below.
- The upper part of the skull of fledgling birds is single-layered. As the bird matures, a second layer develops, and “struts” of supporting bone develop between the two layers. This is known as ossification or pneumatization, and can be viewed through the thin skin of the head if the feathers are wetted and parted. The pattern and rate of ossification varies among species. ↩