Night animals

At night, after people put they garbage bags in the streets to be collected, from nowhere hundreds of wild cats appear to eat (and they are all quite fit, but maybe only in neighboroods where wealthy people live and, i guess, food is left). Sometimes also some wild dogs appear, but if here there are only few i imagine that in more popular parts of the city there are many; as it was in Burundi, wild dogs are all the same shape and colours: here they are big and grey. I wonder what happens to other types of dogs, or maybe they all are born similar.