Fat pigeons are not uncommon, particularly in cities where plenty of
food is easily accessible. Pigeons are scavengers so if food is readily
available they will eat it…and get fat!

Not all pigeons who look fat are fat though, all birds have the ability
to puff up their feathers if they feel cold or unwell. A fat looking
pigeon may simply be doing this.

Reasons Pigeons Get Fat:

Many city pigeons are fat because they are scavengers. Food in cities is
abundant and pigeons often don’t have to work very hard to get it. This
naturally leads to pigeon obesity.

Pigeons (and all birds) have the ability to puff up their feathers so if
a pigeon looks fat that does not necessarily mean it is overweight. They
may just be feeling ill or cold, to counter this they puff up their
feathers to trap air against their skin and keep them warmer.

https://pigeonpedia.com/fat-pigeons/

Many people are fat because food is abundant and they don’t have to work very hard to get it. This
naturally leads to obesity. But food is not so readily available to all people. Some people starve. Even fat people can starve to death. Can't help it Jill. I saw your post on fat pigeons and everything that applies to them seems to apply as well to most earth creatures. Many will eat themselves to death. When I was a kid I had a dog who was still a puppy, a few months old. I was going out for only half an hour or so, so I put a steak on the counter to partly thaw out during my absence. When I got back the puppy was lying in the middle of the floor flat on its back and the steak was gone. I have no idea how he got up there. But he did. Good thing the steak wasn't bigger, he might have burst like a balloon - or a pigeon in central park.