Reproductive biology

Most sturnids are secondary cavity nesters, often somewhat reliant on woodpeckers and barbets for their nest sites. They compensate for an inability to make their own nest cavities with an aggressiveness that often allows them to appropriate newly excavated ones. Other sturnids such as Tristram's red-winged starling (Onychognathus tristramii) make use of niches among rocks, and many have expanded their nest-site preferences to include nest boxes and recesses associated with buildings and other man-made structures.

Once in possession of a cavity, sturnids typically construct a bulky nest of grasses, leaves, fine twigs, and other materials. Sometimes these include man-made objects, and there have been cases of European starlings adding discarded, but lighted, cigarettes to a nest with disastrous results. The amount of material added tends to be whatever it takes to fill the cavity. Red-

billed oxpeckers (Buphagus erythrorhynchus) add the dung of ungulates to their nests. Several species add flowers or green leaves to the nest, and it has been suggested that they may select plants laden with chemicals having insecticidal properties. Both sexes are usually involved in nest construction, and nests may be refurbished and cavities used again and again.

Starling eggs are often pale blue, but sometimes white to cream-colored. They may be solid in color (Acridotheres, Leu-copsar, Gracupica, Sturnia, Temenuchus, Pastor, Creatophora, Sturnus) or have dark spots on them (most species in other genera). The occurrence of colored eggs and eggs with spots has been evidence that sturnid ancestors were open-nesting birds and that cavity nesting is a relatively recent secondary development.

In some cases, only the female incubates; in others, both sexes incubate. Incubation periods are sometimes less than two weeks. Sturnid young at hatching are generally pink, at most with sparse patches of down on top of the head and back, and have their eyes closed for the first few days of life. Both parents contribute to feeding the young and, in some species (e.g., the red-billed oxpecker and possibly the babbling starling, Neocichla gutteralis), there are helpers at the

A common (or European) starling (Sturnus vulgaris) feeding chicks at its nest hole. (Photo by B & C Calhoun. Bruce Coleman Inc. Reproduced by permission.)

nest who feed the young as well. In such cooperative breeding, the helpers are usually offspring of the same pair from earlier efforts. Nestlings often fledge within three weeks, but young oxpeckers may remain in the nest for nearly a month. Many species can produce two, sometimes three, broods in a year.

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