|Kingdom: Animalia Phylum: Chordata Class: Aves (Birds) Order: Coraciiformes Family: Coraciidae|
The following three species are found in India:
Physical characteristics Rollers are medium-sized, heavy-bodied birds with relatively large head, short neck and stout bill. Their Syndactyl feet are proportionately small but strong. They have broad, long wings and a rather broad tail. Size of various species varies from from 26 cm for the Blue-throated Roller (Eurystomus gularis), to 37 cm for the Blue-bellied Roller (Coracias cyanogaster). All species have smartly colored plumage in tones of blue or lilac, with olive, chestnut, or pink markings. The juvenile birds resemble adults. In genus Coracias, the shrike-like hook tipped bill is suited to grasping prey captured on the ground. Birds of genus Eurystomus catch flying insects, and their short, wide bill is well adapted to aerial feeding.
World distribution Africa is the real home of Rollers, where eight of the 12 species are breeding residents. Outside Africa, they are distributed from west Europe through India and rest of Asia to east Australia. Nowhere do more than two species occur together. Western regions of the world range are occupied European Roller (Coracias garrulus) and the eastern regions by Dollarbird (Eurystomus orientalis). Isolated regions in Indonesia are occupied by Temminck’s Roller (Coracias temminckii) and the Azure Roller (Eurystomus azureus).
Habitat Although occurring at high altitudes when crossing mountain ranges during migration, Rollers are lowland birds, frequenting habitats that vary from tropical or subtropical woodland to most types of open country, including grassy hillsides with scattered trees, scrublands, cultivated fields, and urban parks or gardens.
Habits Eurystomus species mark their territory by flying high above treetops and calling loudly. The spectacular rolling flight displays of Coracias species give the birds their collective name; Rollers. The flights feature prominently in marking territory and courtship. They are made with powerful wingbeats as the bird flies 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 warm weather, Rollers are active throughout the day, spending much time sitting on vantage perches looking for prey. Activity levels decline during bad weather. Movements undertaken by Coraciidae vary from seasonal migration, sometimes over vast distances, to irregular wanderings. Near the tropics, the movement is limited to local migration and post-breeding dispersals.
Feeding and diet Vantage perches are of the utmost importance to Rollers, for it is from these that birds pounce to capture prey on the ground or sally forth to catch flying insects. Coracias take mainly large arthropods, almost always from the ground; Eurystomus are exclusively aerial feeders, taking flying insects after sallying forth from a high, exposed perch. Small prey are swallowed whole; larger prey are brought back and struck repeatedly against the perch before being swallowed.
Reproduction Loud calls during flight features prominently in courtship displays of Rollers. The spectacular rolling aerobatics are performed by birds of genus Coracias. Bowing displays are performed by paired birds while perched facing each other. Copulation occurs after flight display, 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. 3–5 white eggs are laid, incubation (18–20 days) is undertaken by both sexes, though mostly by the female. Newly hatched chicks are naked, with pin feathers first appearing at about seven days and full feathering appearing between 17 and 22 days. Both parents feed nestlings for 30 days and for up to 20 days after fledging.
Status Rollers are fairly common throughout all or part of their ranges. The appearance of Indian Roller (Coracias benghalensis) is considered to be a good omen, and it is widespread in India and the rest of South Asia. European rollers passing through the Mediterranean region are hunted for sport and food. The species is widely admired because of its colorful plumage. In last three decades significant decline in population of European Roller (Coracias garrulus) has occurred in central and eastern Europe, but the species remains numerous elsewhere. Only one species, the Azure Roller (Eurystomus azureus) is considered Vulnerable because of loss of forest habitat.