Why does my bird have bald spots?

One question we hear a lot regarding health is “what is this bald spot on my bird? Is it plucking or sick?” While plucking can be a common cause of bald spots, some spots on birds are naturally unfeathered. These spots are a result of “pterylae” or predictable tracts where feathers grow. ​​While each species has some variation in these tracts, they remain fairly predictable across a species. This becomes very easy to see in babies when they are just starting to grow feathers in. This baby cockatiel here gives a good visual example of the bald spot found naturally found on the back of cockatiel heads, and a common bald spot to birds on the chest and belly. We don’t normally see these spots because the feathers around them are wide enough to cover them up. The spot on the belly serves a functional purpose of allowing better heat transfer during egg incubation, and can sometimes get wider during breeding season.