Answer:
In a darker background, natural selection favors the darker birds.
Same goes for a ligter background
Explanation:
There is pressure in a population to look the same, because if you are white in a flock of regular pigeons, you will be targeted by predators, mainly Peregrine Falcons. However, in a city environment, it my benefit you (the pigeon) to be a different color, as more people will feed you. However, due to the release/escape of domestic pigeons, new colors that would not have appeared in the wild population are there.
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