The only problem arises if the "playboy" and "playgirl" genes are so
successful that neither sex takes care of the kids. The opposed strategy of
loyalty to one's mate and investment in the care of one's offspring
(quite certain for females, less so for males) has clearly provided
superior genetic payoffs on average for many birds (and for humans, for
that matter). So we have individuals investing a
bit in the one and a bit in the other strategy. The problem in using
these rather cute anthropomorphic scenarios is that they tend to be used
by humans to justify whatever course of action they happen to have chosen
themselves without appreciating that there are many ways to play the game
successfully with success depending on a complex of factors one cannot
always control....

Gene Hunn.

On Tue, 23 Jan 1996, Dennis Paulson wrote:

> Mike Smith wrote:
>
> >Since when are blackbirds 'nice'? Male Red-wingeds seem to 'rape'
> >females as well. I saw 2 males chase a female around a marsh until she
> >was too tired to get away, they all disappeared into a bush for awhile.
> >I don't know if she ended up copulating with both males or not. But it
> >seems an amorous-feeling Red-wing will sometimes not take 'no' for an answer.
>
> Nature is a lot more complex than most people realize, and in particular
> social behavior can be surprisingly varied. Monogamy is the rule in birds,
> but it's a rule meant to be broken. Males of a surprisingly large number
> of monogamous species that have been studied well are known to be quite
> alert to the presence of a female unguarded by her mate, and a bit of
> dallying may ensue (pardon my anthropomorphism; I'm going for spicy
> writing). More genes in the next generation is the male's reward.
>
> What makes it less of a one-sided picture is that the females, in some
> cases, are more than willing. In this case, *better* genes in the next
> generation is the female's reward, assuming the intruding male is really
> hot stuff (= more fit in one or more traits). To continue the
> anthropomorphic vein, even if he's not more fit per se, if the female
> accepts his "playboy" genes and has "playboy" young that her unsuspecting
> but dependable mate helps her rear, and if *those* young then go on and
> fertilize more than their share of females, guess what? Both the "playboy"
> genes of the male and the "playboy-susceptible" genes of the female
> increase. See how it works?
>
> In birds that breed in large numbers in a relatively small space, the
> interactions get even more intense. A female Red-winged Blackbird flying
> to and from her nest has to do it as quickly as she can, as any male the
> territory of which she passes through will attempt to copulate with her.
> Check out a red-wing colony and see how many "sexual chases" there are.
> And it's not always in vain. In one study, some of the males in a marsh
> were vasectomized, and a surprisingly large number of their females laid
> fertile eggs. You figure it out.
>
> And that's tame compared with Cliff Swallow society. A Cliff Swallow
> colony has the complexity of social interactions of a Malibu Beach condo.
>
> Dennis Paulson 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
>
>
>