The often occur singly, but Hoary-headed Grebes are sometimes also seen in flocks which may comprise hundreds or even thousands of birds. When confronted by a raptor, grebes in a flock may all dive under the water together in a highly synchronised manoeuvre, though at other times they may fly away from danger, staying just above the water. Hoary-headed Grebes often nest in simple pairs, but sometimes they form colonies of hundreds of floating nests, which may be joined together to form a large raft.
