Re: SF and SEFI Red-footed Boobies appear different

Peter Pyle

Have confirmed with Jim Tietz that the Farallon Red-footed Booby was present out there yesterday morning at the same time as the one was being seen near the CG Pier.

At 06:16 PM 11/9/2019, Peter Pyle via Groups.Io wrote:
Hi all -

The good open-wing photos of the RFBO by Joe Morlan et al.
show that it is molting p5 whereas the SEFI bird
Does not show molt and also has a pale tips to the central rectrices which the SF bird lacks. This indicates different birds.

I'm not sure about age of the SF bird now. The bill lacks blue at the base, which adults should show, yet the primaries appear to be showing a "Staffelmauser" pattern, with p1-p4 new, p5 growing, p6 or p6-p7 old and worn, and p8-p10 quite a bit newer looking, suggesting a previous molt limit between p7 and p8. If I'm reading this right then the outer primaries are not juvenile and the pattern including the older-looking p6-p7 would indicate a bird in at least its 3rd or 4th cycle. Perhaps bill color becomes pinker in molting adults away from the breeding grounds?

I'll keep working on it...

Cheers, Peter

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