These birds are compulsive nest builders, constructing three to five nests per year whether they are breeding or not. Barn owls and eagle owls may force them out and take over the nests, but when the owls leave, the hamerkops may reuse the nests.[2] Snakes, small mammals such as genets, and various birds live in abandoned nests, and weaver birds, starlings, and pigeons may attach their nests to the outside.[4]