Turns out that regardless of evolutionary lineage, the animals react in a similar way to life among humans: they lose their antipredator traits. That pattern is especially pronounced for herbivores and for social species.
We produce it as efficiently as possible and the conditions the animals lived in means drugs are often used, not only to keep them alive, but to make them fat.
But in fact, we're now finding that these early immigrants were just the start of a more general movement of animals into cities, and of adaptation by these animals to city life.