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Some birds that build their nests on the ground are flightless birds, such as emus and ostriches, but other birds which can fly are also ground-nesting. These birds include chickens, penguins, killdeer (a kind of plover), and water birds such as ducks, geese, swans etc.
no not all birds
No birds build nests but goats may scrape out an area in the soil to get to the cooler ground.
So their nest doesnt get attacked
Probably none. Birds generally build their own nests. It makes them feel safe.
Some birds do not build nest's .why?
why do all birds build nest
Birds build their nests in different places depending on their habitat. Most build them up in the air, in trees, sides of cliffs and buildings. This allows them to be protected from most of the predators that can't fly or climb. There are flightless birds and many water fowl that build their nests on the ground.
Other Birds
Well birds build nests in them.
the birds know it by heart
building not the structure that is already built but what is happening to the current structure that has not been finished before.