Subject: RE: re quivering swallows
Date: Jun 3 09:45:47 1996
From: Dennis Paulson - dpaulson at mirrors.ups.edu


>Tweeters;
>I'm not sure about the quivering part but the uplifted wings is apparently a
>behaviour to prevent other individuals from landing and copulating while the
>individual is collecting mud. This informational tidbit was obediently
>copied into my notes from a Dr. Dennis P. lecture during a Master Birder
>class.
>Tracee Geernaert

You got it right, Tracee. It's pretty well established that a Cliff
Swallow (both males and females) that holds its wings up is less likely to
get landed on by another Cliff Swallow, in an attempted extrapair
copulation. The original reference is Butler, R. W. 1982. Wing
fluttering by mud-gathering Cliff Swallows: avoidance of "rape" attempts?
Auk 99: 758-761. He merely put out mounted specimens of Cliff Swallows
with wings up and wings down and noted frequency of copulation attempts.
Charles and Mary Brown, Cliff Swallow experts, also have a book in press on
this species that will discuss this further. Apparently much of this quite
adaptive behavior goes on at these mud puddles, quivering wings
notwithstanding. Barn Swallows don't gather in this way so aren't subject
to this behavior.

I love the quote from Bent. Perhaps that "female waiting for the mate at
the nest under construction, ecstatically quivering her wings upon his
approach (with redoubled cries of joy no less)" is actually a female trying
to avoid an extrapair copulation by holding her wings up and squawking!
Not that it doesn't happen anyway; a surprisingly large proportion of young
in nests aren't the offspring of the male parent at the nest. Cliff
Swallow colonies are paradigms of selfish-gene behavior (including a high
intensity of conspecific brood parasitism and egg destruction) in the midst
of what looks like a big, happy, social group. They've got good reasons to
be social, and then, being social, have lots of close neighbors on which to
practice selfish pursuits.

This is of course always the trouble we get into while anthropomorphizing
about other animals; good thing people are out there actually trying to
understand what's going on.

Dennis Paulson, Director phone 206-756-3798
Slater Museum of Natural History fax 206-756-3352
University of Puget Sound e-mail dpaulson at ups.edu
Tacoma, WA 98416