Rare Brewster’s Warbler at Pavones, near Turrialba

The big excitement on my trip with Andrey and Steven to Pavones was caused by a hybrid Golden-winged Warbler (Vermivora chrysoptera) that turned out to be a backcross (?) adult male Brewster’s Warbler (Vermivora chrysoptera ?) that associated with other warblers up at the top of the Torre Alta Lodge property. Steven Aguilar managed a couple of rather blurry photos but they nonetheless would seem to confirm the very rare sighting:

We knew it was a Golden-winged Warbler, but an unusual one!

We knew it was a Golden-winged Warbler, but an unusual one!

 

Hello! The Brewster's peers down at us and is recognisable despite the backlighting

Hello! The Brewster’s peers down at us and is recognisable despite the difficult backlighting

Hybrids in themselves confuse me, but a backcross? It turns out that this is the product of a Golden-winged Warbler and a Brewster’s hybrid.  Golden-winged/Blue-winged warbler hybrid forms are termed “Brewster’s” (mostly light-grey) or “Lawrence’s” (mostly golden in colour). If your’re interested, see the following link for a very detailed explanation of the situation with hybrids plus a detailed discussion of the reasons for the recent population crisis with chrysoptera.

https://www.aba.org/birding/v37n3p278.pdf

Here’s a clear view of a Golden-winged male banded down at CATIE some years ago:

Male Golden-winged Warbler showing black throat patch absent on the Brewster's.

Male Golden-winged Warbler showing black throat patch absent on the Brewster’s.

These photographs have been submitted to eBird for confirmation (we hope) and detailed expert comment.

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