All depends on the bird. A lot of birds build their nests with branches, leaves, feathers, and occasionally pieces of trash lying around. Most use sticks for the structure and the use feathers and leaves for bedding. When I said trash, I meant pieces of strong yarn, anything soft.
Some birds do not build nest's .why?
Birds typically build their own nests for shelter, but some species may use abandoned nests from other birds.
Well birds build nests in them.
the birds know it by heart
Birds
in trees
No birds build nests but goats may scrape out an area in the soil to get to the cooler ground.
Their usually sticks.
Because you are stupid
Birds build nests to protect their eggs.
No, weaver birds typically build individual nests for mating purposes and do not allow other birds to join their nests. Each pair of weaver birds will construct their own nest as part of their elaborate courtship display.
eagles or valtures