Dennis Paulson wrote,
> When birds leave the nest hole above me and fly out onto the lawn, they
very
> commonly (not sure if it's invariably) join little flocks of starlings
already feeding.
> There is plenty of open starlingless lawn, yet the starlings choose to
feed rather
> close together. Apparently they are territorial when nesting but social
when
> feeding, not a common combination in passerine birds.

Dennis, interesting observations. You and I have had discussions before
about the adaptationist viewpoint and whether every feature an organism
displays has a function. This social feeding is probably functional, isn't
it. Several birds moving across the grass together probably scare up more
small invertebrate food than a single bird does, and together they may
exploit the resource more completely than a single bird would. Have other
people observed social feeding behavior like this and speculated on its
function? In response to my suggestion, someone is likely to raise the
objection, "Well, if social feeding of this kind is so valuable, why don't
all passerines do it?" The answer, of course, is that a species can't
simply order potentially adaptive features from some Great Warehouse in the
Sky; it must wait to get the proper genes, more or less by accident, and the
genes and the behavior must fit with the rest of the genome and the rest of
its behavioral repertoire.

What do you think.

Burt Guttman
The Evergreen State College 360-867-6755
Olympia, WA 98505 guttmanb at evergreen.edu

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