How long does it take baby birds to leave the nest?

Depends on the species. Do you know what kind of bird it is?

Most fledglings near your house will be part of the family of American songbirds. My experience has been that they leave the nest when they are wobbly fliers and fair game. It takes several days for their wings to get strong enough for them to flee a cat. I found a dead (and still warm) fledgling sparrow in my bedroom the other day, having had this loaner cat for 72 hours.

don’t know what kind of birds, but they will have zero chance of survival with my cats on the prowl. My cats are avid hunters. They’re already hoovering on the birdhouse and hanging on the lattice to get close to them. Literally!

I believe we have a pheobe (febbie) bird. The nest was built on 4/5/09. Now and then the bird flys in and out. What would be the duration of this nesting? We want to be sure not to disturb. Also when to we know to remove the nest?
Thank you

Do not remove a phoebe nest. If they feel secure, they will return year after year. I have one that is very easy to peek into and it is built high enough so that my cat couldn’t get to it unless he grew spurs.

Check to see whether there are eggs. Once the eggs hatch, phoebe fledglings flee the coop in 7–10 days on average. They are most vulnerable when they first try to fly. Some of them fall to the ground. It really is nature red in tooth and claw.