[Tweeters] Unusual Anna's Hummingbird Feeding Behavior

[Mike Wagenbach]

I haven't noticed highly docile/sociable Anna's this year, but I saw one
unusual event last year:  It was during a cold snap when I had to bring the
feeders in at night to prevent freezing.  One morning I put them out at
dawn and almost immediately saw all four perches of the feeder filled with
birds, who drank more or less continuously for what seemed like a long time
(a minute or two) with almost no interaction between them.  This tolerance
didn't last long, and within a few minutes, certainly less than ten,t there
was a lot of chasing and defending the feeder, as usual.  My assumption was
that after an unusually cold night, they were desperate to feed and didn't
have the energy for the typical chases right at first.

This comment thread makes me wonder if there could be some evolution of
behavior occurring as a result of consistent feeder maintenance around our
homes.  While needlessly defending an almost limitless resource
(particularly during the non-breeding season) seems like a waste of energy,
no doubt it promotes differential survival for the bird doing the
defending.  However, if that reduces the survival through the winter of
that bird's sons and daughters, and even siblings, cousins and
nieces/nephews, which seems likely, particularly if they have site-fidelity
to where they spend successive winters, that would set up a potential
kin-selection benefit to not defending the feeder.

Has territoriality in Anna's been studied carefully enough to detect
changes in the behavior?

Mike Wagenbach
Seattle (Ballard)
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman11.u.washington.edu/pipermail/tweeters/attachments/20211126/0a779ef9/attachment.html>