The origin of the dollbird's name stems from the silvery, circular patches on the underside of the wings. thought to resemble the American silver collard coin. In flight, the pale blue coin-shaped patches towards the tips of its wings are clearly visible. Both sexes are similar, although the female is slightly duller. Young dollarbirds are duller then the adults and lack the bright blue gloss on the throat. The bill and feet are brownish in colour instead of red.
The dollarbird arrives in northern and eastern Australia in September each year to breed. In March and April the birds return to New Guinea and adjacent islands to spend the winter. In Australia the dollarbird inhabits open wooded areas, normally with mature, hollow-bearing trees suitable for nesting.
This bird feeds almost exclusively insects, and appear particularly fond of hard=skinned flying insects like beetles but they will take any large insect or even feed on swarming insects. They search for food from a conspicuous perch and then capture it in skilful aerial pursuits, before returning to the same perch. Occasionally, they have been seen feeding on grasshoppers on the ground, although this practice is uncommon, and also catch other small animals.
Dollarbirds are aerial feeders and like other rollers are flying acrobats, wheeling and swooping about. They catch insects on the wing with their short flat bills that are broad at the base. They may also take insects and lizards from on the ground. Large insects are brought back to the perch, to be beaten to death and to knock of less edible bits like hard wing cases. They feed in the cooler afternoon and evening, During the hottest part of the day they may hide away or simply remain motionless on their favourite perch.
During breeding season, dollarbirds are seen flying in characteristic rolling flights. These flights are more common in the evening, and are accompanied by cackling calls. The white eggs are laid in an unlined tree hollow and are incubated by both adults. The young birds are also cared for by both parents and the same nesting site may be used for several years. The youngsters don't have the colouring of their parents.
The Anula tribe of Northern Australia associate the dollarbird with rain, and call it the rain-bird. A man who has the bird for his totem can make rain at a certain pool. He catches a snake, puts it alive into the pool, and after holding it under water for a time takes it out, kills it, and lays it down by the side of the creek. Then he makes an arched bundle of grass stalks in imitation of a rainbow, and sets it up over the snake. After that all he does is to sing over the snake and the mimic rainbow; sooner or later the rain will fall. They explain this procedure by saying that long ago the dollarbird had as a mate at this spot, a snake, who lived in the pool and used to make rain by spitting up into the sky till a rainbow and clouds appeared and rain fall (From Sir James George Frazer (1854-1941) The Gold Bough. 1922. Ch. 2. The Magical Control of Rain).
There are of course other 'rollers' and dollarbirds in other part of the world. I have just included here the particular dollarbird that visits our shores.
Goodnight, sleep well little dollarbird.