To respond to Chris Hill's comments about Red-winged and Yellow-shouldered
blackbirds.

There really is a substantial difference between the territoriality of male
redwings and that of females. Females defend their little territories
within that of a male, once they've mated, but it's the polygynous male
that displays and tries to attract as many mates as it can. Real macho
stuff, long-distance display, very different from the females (the red
epaulets of which some have speculated mimic those of the males and do
indeed function in territory defense).

I'll bet that territory defense is much more shared by the sexes in the
monogamous Yellow-shouldered Blackbirds while on the breeding grounds, even
though they flock thereafter.

To me, the really fascinating thing is that so many tropical females are
brightly colored, yet incubate the eggs, while one of the convenional
wisdoms about temperate-zone dimorphic passerines is that females have been
selected for cryptic coloration because they are at the nest. Hmmm, maybe
not.

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