Behavior

Little is known of the life and habits of shy, secretive ground-rollers, but available information indicates they are essentially terrestrial, especially when feeding, and usually encountered singly or in pairs. Instead of flying, they prefer to escape danger by running or standing motionless in a well-concealed position. The brief, guttural call notes are heard mainly during breeding season.

While on migration, some true rollers gather into loose flocks that may come together in large aggregations. However, for most of the year they are strongly territorial, normally encountered in pairs or post-breeding family parties. In the breeding territories, they are noisy and conspicuous, with loud cackling call notes that constantly accompany spectacular aerobatics. This contrasts with quiet, often lethargic behavior in wintering areas. Eurystomus species advertise territorial occupation by flying high above treetops and calling loudly, but the spectacular rolling flights undertaken by Coracias species give the birds their collective name. The flights feature prominently in territorial and courtship displays. They are made with powerful wingbeats as the bird flies

A dollarbird (Eurystomus orientalis) emerges from its nest in a tree hollow in Australia. (Photo by J. Warham/VIREO. Reproduced by permission.)

up at a steep angle, then suddenly tips forward and plunges down with rapid wingbeats while rolling the body from side to side before leveling out and moving away to repeat the sequence. In fine warm weather, true rollers are active throughout the day, spending much time sitting on vantage perches awaiting the appearance of prey. Activity levels decline, often significantly, during rain. Movements undertaken by true rollers vary from regular, seasonal migration, sometimes over vast distances, to local, irregular wanderings. Toward the tropics, seasonal migration tends to be replaced by irregular local movements or post-breeding dispersals.

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