Jon Dunn/FIELD NOTES

Female Grosbeaks (Rose-breasted and Black-headed)

The Western Tanager, March 1977

Female-Grosbeaks-illustration-by-mary-ellen-pereyra

Illustration by Mary Ellen Pereyra

Rose-breasted Grosbeaks are rare but regular vagrants to California during late spring and autumn, and usually a few winter at feeders and other thickly-vegetated locations along the coast. Statistically, in fact, the Rose-breast is more likely than the Black-headed in winter, so every female and immature sighted should be examined with care. The mature males of these two species present no problems of identification. The young male Rose-breast basically resembles the female, but it normally has a trace of rosy color in the breast—and in flight the bright pink underwings will immediately separate it from any plumage of the Black-headed.

Telling the females apart, however, is another matter. Not only are the birds very similar, but the problem of identification is compounded by the fact that the plumage is somewhat variable, and the key characters emphasized in the field guides are not entirely reliable. Apart from the call note, no single character is, in itself, diagnostic—so the birder must rely on a combination of characters to identify the bird in question. This is especially the case if the bird shows ambiguous characteristics.

Probably the best field mark on the female Rose-breast is the heavy dark streaking running vertically across the whitish breast. The Black-headed tends to have a more buffy breast, with very fine streaks-restricted only to the sides of the breast. Also, the head stripes of the Rose breast tend to be whiter than the buffy stripes of the Black-headed. In addition, the Rose-breast has slightly more prominent back streaks, and the wing linings are a slightly brighter saffron hue—as opposed to the duller buff wing linings of the Black-headed.

Unfortunately, though, these marks are not always definitive. The female Rose-breast can sometimes have very thin streaks across a breast that has a slightly buffy cast. And conversely, the breast of a Black-headed can become quite worn (in late spring and summer), so that the buffy cast disappears. Logically, then, some birds must remain unidentified. Unless they are heard....

Although both species give a whistled wheet flight-note, the regular call notes of the two birds are diagnostic. The call note of the Rose-breast, a shark eek, is much more high-pitched and squeaky than that of the Black-headed. If one learns the call of the common Black-headed Grosbeak, then the call of the Rose-breast should sound quite distinctive, and provide confirmation of identification.

Originally Published in Western Tanager, Vol. 43 No. 6, March 1977


 

Transcribed for the Los Angeles Audubon Society (LAAS) Western Tanager "Articles from the Archives" www.laaudubon.org. July 2013 by SMC.