How can birds still fly if they have to constantly eat to have enough energy to fly? Doesn’t eating make them so heavy that they need even more energy to keep flying?

Question

When I watch the birds at the feeding station in my garden, I notice that individual birds often eat a lot at once. Doesn’t all that food make them so heavy that they need more energy/food to fly than they can carry in flight?

In: Biology

Answer 1

They also poop a lot. Bird digestive system works fast and they don’t store their poop like we do, they get rid of it quickly.  

I have a pet bird (Wood Pigeon) and when he eats he poops, a lot.  

Still, he’s quite a chunky bird and can fly despite that. They just evolved this way. Their feathers often weigh more than their skeleton, they have very strong muscles for the wings, and it’s more beneficial for them to load up in a single sitting than to be vulnerable more often by eating less but more frequently.  

They also only need energy for flying when they’re taking off, accelerating or changing direction. Once they get to a decent altitude they can glide on open wings for long distances without using much if any energy.