Re: [cobirds] Leucistic Blue Grosbeak?

It's first year male plumage. They always look messy like your bird to some degree.

Chris Hobbs

chobbs.f1@gmail.com 

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From: cobirds@googlegroups.com <cobirds@googlegroups.com> on behalf of James Ward <darthgeek.jw@gmail.com>
Sent: Friday, May 30, 2025 4:30:52 PM
To: cobirds@googlegroups.com <cobirds@googlegroups.com>
Subject: [cobirds] Leucistic Blue Grosbeak?

 

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, darthgeek.jw@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.

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