Hi all --
I've noticed several people saying things like "Male mallards do forced
copulations so they can increase the number of young that they
have."

I think it's essential to remember that that may be the reason that the
behavior EVOLVED, but the male mallard is almost certainly NOT consciously
aware of this reason. The more immediate reason that the drake forces a
female to have a copulation is probably an internal motivation that is
something like "I want to copulate with this hen" (speaking
anthropomorphically). Male drakes almost certainly have no idea that
copulation results in baby ducklings!

This is the distinction between "ultimate" causes (why did the behavior
evolve over the long term) and "proximate" causes (how is the behavior
triggered in the short term; what is the animal's immediate motivation).
Every type of behavior has a proximate cause(s) AND often has an ultimate
cause(s) too. Animal behavior literature focuses on ultimate causes.
Human literature focuses on proximate causes. So, when we compare animal
behavior to human behavior we must be clear about what kind of "cause" we
are talking about; otherwise we get garbled comparisons like "those drakes
are trying to increase their offspring, but human rape is due to violent
urges toward women", which is comparing an ultimate cause in one species
to a proximate cause in another, and is pretty much a meaningless
statement.

This may all be obvious, but I thought I'd point it out anyway...

Oh, and someone asked about homosexuality in gulls. Those are the famous
"lesbian Western Gulls". Female-female pairs are relatively common in
some populations of Western Gulls. The females court each other, seem to
have stable pair-bonds, lay eggs, and share incubation, just as
male-female pairs do. Sometimes these "lesbian" females will copulate
with males elsewhere in the colony (males mated to other females), and
then some of the female-female pairs' eggs will hatch, and the two females
can raise the chicks successfully. The colony that this was best studied
in had a very skewed male:female ratio, about 1 male to 3 females if I
remember correctly, and so this "lesbianism" may just be the best
reproductive strategy available to females that couldn't get a male of
their own. (speaking of ultimate causes here, of course.)

In the popular press, the lesbian gull study has, for some reason, gotten
garbled up with a totally separate lab study on DDT's effects on California
gull eggs, resulting in the tasty factoid "DDT causes lesbianism in
gulls!" In fact, I saw this statement again just a couple weeks ago in a
New Yorker article. There's no evidence for it; it's a bogus hybrid
story. But such are the strange and mysterious ways of the U.S.
media....

cheers,

Kathleen Hunt
U.W. Zoology