Thursday 6 November 2014

Rose-breasted Grosbeak x Black-headed Grosbeak

presumed Rose-breasted Grosbeak x Black-headed Grosbeak hybrid, Bayfield Riverside Park, La Plata County (Colorado, USA), 4th June 2014 - copyright Steve Mlodinow
(photo ID: 1636)

Steve notes that the colour is limited to the chest, with more reddish hues centrally, combined with the largely white underparts.  This would be unusual for Black-headed Grosbeak (even first year male) and common among hybrids.  Furthermore, Steve says, the white striping on the head is a Rose-breasted Grosbeak trait.  Black-headed Grosbeaks usually show buff stripes.

presumed Rose-breasted Grosbeak x Black-headed Grosbeak hybrid (same bird as in photo ID 1636 above), Bayfield Riverside Park, La Plata County (Colorado, USA), 4th June 2014 - copyright Steve Mlodinow
(photo ID: 1637)

Steve says he consulted with several others about the next mystery bird.  Their advice points to it likely being a female, probably an older bird showing male-like traits.  That explains the bright orange-tinted yellow triangle on chest which would point to Rose-breasted Grosbeak, albeit aberrant.  However, the streaking is more like Black-headed Grosbeak as is the buff in the forward portion of the supercilium.

Steve points out that both photos are a bit off colour-wise.  The first was exposed more correctly, but there was some blur due to slow shutter speed, making the streaking appear less prominent (and there's a peculiar green hue which is unexplained).  The second photo was underexposed, but shows basic patterns better.

Rose-breasted Grosbeak x Black-headed Grosbeak hybrid, Apple Valley Road, just west of Lyons, Boulder County (Colorado, USA), 15th June 2012 - copyright Steve Mlodinow
(photo IDs: 1160-1161)

The next one is believed to be most likely an adult female in fresh winter plumage.  Steve notes that the heavy streaking on sides/flanks seems beyond the range of a Black-headed Grosbeak at this season (some juveniles approach this).  Also, the intensity of colour on the chest combined with the rather white belly seems odd for a Black-headed Grosbeak.  On the other hand the orange throat as well as chest seems unlike a Rose-breasted Grosbeak, and if an adult female, one would expect more streaking on centre of chest.

Rose-breasted Grosbeak x Black-headed Grosbeak hybrid, Santiago (Baja California Sur, Mexico), 13th December 2011 - copyright Steve Mlodinow
(photo IDs: 1342-1344)

For the next one Steve writes:
"The fine streaking is like that of BHGR, but the extent is more that of RBGR (streaking on undertail coverts not right for BHGR?). The color beneath is yellow, but forms a triangle. In this apparent female, one would wonder why the color would be in the distribution of a male RBGR, but in the 3 other female-type hybrids that I've found, this has been the case. The bill is diffusely pink with some vague duskiness, in between BHGR and RBGR."

apparent Rose-breasted Grosbeak x Black-headed Grosbeak hybrid, Stulp Farms, Prowers County (Colorado, USA), 20th May 2015 - copyright Steve Mlodinow
(photo IDs: 2257-2260)

Rose-breasted Grosbeak Pheucticus ludovicianus
Black-headed Grosbeak Pheucticus melanocephalus


  1. Saw this female RBGBxBHGB hybrid on May 19, 2017, in Cortez, CO at a bird feeder.

    1. Great... don't suppose you got any photos?

  2. I respectfully disagree with the good doctor (hi, Steve!), as I've found a number of online photos of SY male BHGR that look quite similar to photos 1636/37. Yes, the supercilium is typically more rufousy on SY males than on this individual and others that I found online (although in none of the photos are they entirely white). Similarly, the entire underparts are typically more rufousy, as well, although one can still see dabs of that color on the sides, mid-belly, and vent on this bird. In photos of more clearcut male hybrids I've uncovered, the lower underparts tend to be more starkly white. More significantly, I have yet to see a photographed hybrid with a strip of yellow projecting down the central belly. In those hybrid photos I've seen, that stripe is always the same rufousy color as the breast, which would apparently indicate RBGR influence. Lastly, the bill color looks entirely appropriate for a BHGR. So, I just don't see that necessary degree of intermediacy indicative of a hybrid.

    1. Sorry Jim - I missed this comment when you made it last year. May I just clarify - is it just the bird in photos 1636-37 that you're questioning, or all of them? To be honest as a British birder I've little enough experience of pure normal-looking birds let alone intermediate-looking ones (hybrid or not) so am very much relying on expertise of North American birders.

  3. Not sure why this comment registered as "unknown."

    regards, Jim Pike

  4. I have a photo of a bird from Cheyenne County KS that I wonder if it could be a hybrid. How could I send it to you?

  5. Im seeing what appears to be a hybrid male in rooks County kansas, see him daily, have photos off camera phone, not good pics, how ever, seeing rbgb and bhgb as well this one is different 7 4 21

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