Excerpts from Jim Conrad's
from the September 26, 2004 Newsletter issued from the Sierra Nevada foothills
somewhat east of Placerville, California, USA
Right now all I'm seeing the species do is to wander about in small flocks gathering acorns. When a bird finally chooses one, it flies away to store it, often wedging it in fissures or behind loose bark-plates on tall, dead pine trunks.
Despite their innocent appearance, I can't forget that among all bird species this one practices some of the kinkiest social behavior. Some Acorn Woodpeckers, MELANERPES FORMICIVORUS, carry on monogamous relationships among themselves, but others practice "cooperative polygyny." In these polygynous relationships there may be 1-3 egg-laying females who mate with 1-7 males, who compete with one another for the right to mate with one or more of the females. In groupings with more than one female breeder, the female "cobreeders" lay their eggs in the same nest cavity. Each female lays about 5 eggs, but clutches with more than one laying female can have up to 17 eggs.
All is not peaceful in such relationships. Nesting females compete with one another to the point that they regularly destroy the eggs laid by their cobreeders. Once the females have decided among themselves who has which laying rights, then egg destruction stops. Nor are males at ease with this setup. Sometimes you see a male rush in and try to stop a copulating pair. Once the nest is in place, things calm down and both males and females incubate the eggs. Nonbreeding individuals also may belong to such groupings and help raise the young.
You just have to wonder why the Creator has produced a bird species in which moments of "marital conflict" appear to be inevitable. Of course, a bird's jealousy and anguish wouldn't be anything like that of a human's. Still, the fact that females break one another's eggs and that males may try to break up one another's matings is evidence of serious mental disturbance among them.
In the end, it looks like it's the same old story: The Creator really has a thing for experimentation and diversity, even when it means heartaches and ulcers for us creations.