Behavior And Reproduction

Most of the Ciconiiformes birds gather in big groups called colonies when they roost at night and when they breed. If they migrate, they usually fly in huge flocks—when birds gather in colonies, they are usually safer from predators that might harm them. Colonies may include many different kinds of herons, storks, and ibises, for example, or they may be made up of all the same species. A few kinds of wading bird pairs stay by themselves when they breed.

For the most part, these birds are not noisy. The vultures do not have a voice box, so the only sounds they can make are soft wheezes and whistles. Storks, shoebills, ibises, and spoonbills also have very little to say most of the year, but some of them squeal, croak, and clap their bills when greeting a mate. The herons are noisier year round, and the loudest birds in the group are the bitterns. They make booming calls to attract mates or proclaim their territories.

Depending on where wading birds live, they nest at different times of the year. The best time to nest is when the most food is available so there is plenty to feed the young. Spring and summer is nesting time in the cool weather of the temperate areas. In the warmer subtropical areas, the birds tend to nest during the dry season to avoid the threat of flooding. The birds that live in the tropics near the equator usually nest in the wet season when food is most plentiful.

When wading birds are ready to nest, the males arrive at the nest site first. They defend their territories by stretching and flapping their wings. When the females arrive, the birds often greet each other with a courtship display. This may include bill snapping and tapping, and smoothing each other's feathers. The females usually build the nests with sticks brought by the males. After the eggs are laid, the parents take turns sitting on the eggs and feeding the young. The chicks are blind and almost naked when they hatch. The parents feed them by regurgitating (spitting up) food on the nest floor or by letting the chicks eat it from their open bills.

The New World vultures do not build nests. They lay their eggs on the ground in caves, under bushes, in large tree holes, or even in abandoned buildings. Vulture chicks depend on their parents for a long time. Young condors do not learn to fly until they are six months old.

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