system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do some animal species (e.g. pigeons and squirrels) beg for food from humans in big cities like NYC, while other species (cardinals, blue jays, rats) do not?

It seems like only a select few animals will reliably approach a human who's eating in hopes for a handout, while other animals are never seen exhibiting this behavior. Why is that?
gpt
Quite often it's because those species are used to humans, and often those Humans will be like "aww cute squirrel" and give a handout. So the animals learn that "humans = free food" and will keep coming back. (Imagine a dog learning to sit or give a paw, and when successful they get a treat. So in future they start sitting/giving a paw in the hopes of further treats)

Compare this to say, a rat, which is more frequently met with borderline hostility. So they learn to stay away from humans and either scavenge/sneak around for scraps.