Re: How long can birds fly before they must stop to rest?

That depends on the bird!

Different birds have different flight styles, and all use different amounts of energy. Turkey vultures and red-tailed hawks are soaring birds; when they fly, they use very little energy, since they are mostly just floating on the winds. They can fly for hours at a time. On the other hand, some of the smaller birds that flap wildly need to rest more often.