Some animals don't have nests because they have adapted to their environment in other ways like a pack of wolves live in a cave, can you imagine a pack of wolves in a nest? No because that would mean different adaptations to build a nest with such as some thing to carry matterials back with or something to build it with, Wolves do not have these adaptations they are adapted to caves instead.
Some birds do not build nest's .why?
So their nest doesnt get attacked
Other Birds
why do all birds build nest
Sometimes they can make out where a nest came from or if it is man-made or not. They will probably live there if they don't have a choice, but some birds would rather build their own nest.
prior to
A kind of bird that lives in the Amazon decorates its nest with small blue pebbles and some birds build their nests on top of rocks as support.
The time it takes to build a nest can vary depending on the species of bird. Some birds can build a nest in just a few days, while others may take several weeks. Generally, most birds complete their nest within 5-10 days.
Many birds make their nest on a tree such as a Woodpecker, Nuthatch and a Tree Creeper.
The weaver birds build their nests in large colonies, and are ball shaped, with the opening to the nest at the bottom.
Themselves - it's a natural thing all birds do
cause they are really high