Leucistic Blue Grosbeak?
James Ward
I attached two photos of what looks to me to be a leucistic Blue Grosbeak. Prior to sending this email, I consulted with ChatGPT on what she thinks. Does AI make sense for birding questions?
Thanks!
Jim Ward, darthg...@gmail.com
ChatGPT response:
"This bird does appear to be a Blue Grosbeak (Passerina caerulea), but with highly unusual coloration.
Here’s what stands out:
- The bird has typical Blue Grosbeak structure: large, conical bill; stocky body; and thick dark feathering.
- It shows blue patches on the face and underparts, which is consistent with a male Blue Grosbeak.
- However, the rest of the plumage is much duller or brownish-tan rather than the vibrant deep blue typical of a fully mature male. The wings show strong contrast but not the usual rich rufous wingbars.
- The coloration appears patchy, suggesting an abnormal pigment condition.
Likely Explanation:
This is probably a partially leucistic Blue Grosbeak or a hybrid/variant with an unusual molt or feather pigmentation issue. Leucism can cause irregular patches of normal and pale coloration, and that’s consistent with what’s seen here. It’s not a textbook leucistic example (which usually has much more white or pale), but leucism manifests in a wide range.
Alternatively, this could be:
- A young male molting into adult plumage (but the bill and body size suggest full maturity).
- A diet or health-related pigment disorder during feather development.
Summary:
Yes, this is very likely a Blue Grosbeak with an unusual pigmentation condition—probably a mild or irregular case of leucism. It’s a rare but documented phenomenon in many bird species.
Chris H
Sent: Friday, May 30, 2025 4:30:52 PM
To: cob...@googlegroups.com <cob...@googlegroups.com>
Subject: [cobirds] Leucistic Blue Grosbeak?
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