No. Some birds nest on the ground (curlews), some (woodpeckers) make holes in trees and some lay their eggs in other birds nests (cuckoos).
OWLS
Nothing really. A tree is a plant, and an owl is a bird. Owls often nest in trees is one possibility.
Mother Bird and Father bird,they help eachother to get stuff done faster
Owls have a nest.
Owls are the only birds that can see the color blue.
in a owls nest
Burrowing owls' nest can be found exactly where their name suggests - in burrows.
Yes, some owls will eat other birds. Only some owls do this though.
yes
twigs
which bird makes a nest in the hollow of a tree
there aren't many trees where they live so they nest on the ground.