Field guide training: Birds – Part 3

Most birds breed in nests. Depending on the bird species, these vary greatly in shape, colour and material of which they are made. The "classic" round nest, made of grass, leaves and feathers, is only one of many types. There are also cave nests, hanging nests, clay nests, brood caves or simple brood hollows at the ground or on rocks.

Some types don't even build own nests at all but use the nests of other types in order to lay its eggs. The cuckoo is a good example for such kind of brood parasitism. This cuckoo also leaves its offspring with the host bird, until this becomes fledged. Sometimes the cuckoo nestling even pushes the “original” offspring out of its own nest in order to provide itself an advantage with feeding.

In general, all bird chicks can be divided into two groups: So-called altricials are naked and blind after hatching and thus completely defenseless. They stay in their nest for a few weeks until they learn how to fly. Most birds whose offspring is altricial build their nests in higher altitudes (trees, bushes, rocks). The chicks of most ground breeding types are precocials.

Shortly after hatching, they are already able to leave the nest and to follow the mother. Accordingly, the feathers are already formed and the eyes opened. This group includes, for example, ducks and most other water birds.

An interesting phenomenon is the socialisation of some bird species in relation to nesting. These are so-called colony breeders. A well-known example are the African Ploceidae which build huge structures on trees consisting of many individual nests.