I went to the Project Pigeon Watch page,
http://birdsource.cornell.edu/ppw/watizppw.htm recommended by another
tweetster recently. It says:

"Project PigeonWatch is an international survey of pigeon flock coloration
and behavior. Its primary goal is to learn why pigeons exist in so many
different colors.

Are some colors better for attracting mates?

Are some colors better at hiding from predators?

PigeonWatchers will help us find out!"

In the page called Why Watch Pigeons, Andre Dhondt offers a little more
detail on hypotheses about why pigeons are so colorful. He suggests that
the lack of predation in cities allows odd-colored pigeons to survive
(essentially the removal of the selection pressure followed by genetic drift
theory). He also suggests that pigeons may prefer certain colors in mates
and or that certain colors are associated with dominance and hence those
dominant birds get to eat more.

I thought all this was interesting because I have always assumed, without
giving it much thought, that Rock Doves were so variable in color because
people have a tendency to notice the odd-colored bird in a flock and are
more likely to toss the food in that direction. Hence, the bird that is
most different from the crowd will, on average, get more food. The low
level of predation on pigeons in cities is presumably not high enough to
offset the value of more food.

But then, if the preferential-feeding-by-people hypothesis is correct,
then one wonders why House Sparrows have not gotten more colorful. Maybe
they aren't as dependent on hand-feeding? Or they have so many more
predators that more food doesn't offset higher predation?

Kelly Cassidy
Seattle