Reproductive biology

A summer breeding season has been recorded for ground-rollers, with egg-laying occurring mostly in December. Pairs defend nesting territories, and courtship feeding of females by males has been observed. Little is known of nesting behavior, and the nest of the short-legged ground-roller—the only species known to nest in tree hollows—was not discovered until 1996. Other species nest in a chamber at the end of a burrow excavated by the birds in the ground, and usually two, but up to four, white eggs are laid. Incubation seems to be undertaken only by the female, and nestlings are fed by both parents.

Loud vocalization during flight features prominently in courtship displays of true rollers, but spectacular aerobatics are performed only by Coracias species. Bowing displays are performed by paired birds while perched facing each other. Copulation may occur after display flights, or more frequently after the bowing display. For long-distance migrants, courtship begins during spring migration, and nesting gets underway soon after pairs arrive in breeding territories. Nests mostly are in holes in trees, but sometimes in crevices in cliff faces or building walls. Clutches are 3-5 white eggs, and for 18-20 days incubation is undertaken by both sexes, though mostly by the

Newly hatched European rollers (Coracias garrulus). (Photo by IFA. Bruce Coleman Inc. Reproduced by permission.)

female. Newly hatched chicks are naked, with pin feathers first appearing at about seven days and full feathering being acquired between 17 and 22 days. Both parents feed nestlings for some 30 days and for up to 20 days after fledging.

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