Night Pigeons Evolving in Pittsburgh

I observed something a bit unusual last night. I have noticed that some pigeons have taken to nighttime flying and roaming about on city streets. Last night I paid a bit more attention. What I noticed was the bird's coloring. Not the usual light grey with darker patches. This one was nearly all black - with some gray on its tail feathers and on the undersides of its wings while flying. This is probably to protect it from night predators like birds of prey and bats - though I don't think the local bats get big enough to kill a pigeon. A lighter colored pigeon would be more noticeable at night and at higher risk. They are not coming out in great numbers - only a daring few - taking advantage of the lighted streets and plenty of food to be found. They're developing their own new niche. It's something interesting to watch develop. I just love evolution in action!