Reproductive biology

Males of most species call frequently to advertise and defend their territory. Aerial pursuit, exposure of plumage patterns in special joint displays, and courtship feeding of the female by the male are all reported prior to copulation and nesting. Food is always held head-out in the bill during breeding to allow its passage to the female or chicks. Both sexes take some part in nest excavation and cavity choice, usually in an earth bank, less often in rotten wood or in a terrestrial or arboreal termite's nest, and occasionally in a natural tree hole. Excavation is started by flying bill-first into the surface, continued later by pecking and scraping out debris with the bill or feet. The entrance tunnel, 3-26 ft (1-8 m) long depending on site and species, usually leads into a larger nest cavity, but no special lining is added. In most species, each pair nests alone, but a few species breed cooperatively, whether they are attended by helpers or nest together in a colony. Kingfisher eggs are white, round, and shiny. An egg is normally laid daily, but the size of an average clutch, ranging from two to seven, depends on the species. Both sexes usually take part in incubation and care of the young, although the female usually remains at the nest overnight. Incubation takes two to four weeks, and the nestling period three to eight weeks, related to the size of the species. Chicks hatch naked and blind, with the upper mandible of the bill notably shorter than the lower. Later, when the feathers emerge, they are retained in their quills initially, giving the chicks a prickly porcupine-like appearance. There is no nest sanitation, other than that chicks may loosen soil from the chamber walls to partly cover their droppings. Nests, especially those in earthen tunnels, often become smelly and full of maggots as feces and food remains accumulate. The chicks continue to be fed by the parents after fledging. They become independent within a few days or weeks and are sexually mature within a year.

Belted kingfisher (Megaceryle alcyon) chick swallowing fish in nest. (Photo by Anthony Mercieca. Photo Researchers, Inc. Reproduced by permission.)

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