The dollar bird (Eurystomus orientalis) is a species of roller from the genus Eurystomus and is common in Thailand. It is a bird with a wide range that reaches from India to Australia. The name refers to the round white spots, one on each wing, these spots look like silver dollar coins (see photo).
The dollar bird is 28,0 to 30,5 cm long. It is a stocky, dark, greenish bird, with a short red beak. The head is colored dark brown. The bird has long wings, like the other species of roller, it is a pronounced aerial acrobat. On each wing is a light, translucent-looking white spot the size of two silver dollar coins used in the United States until 1935.
This insectivorous bird is found as a breeding bird in the north of the Indian subcontinent, throughout Southeast Asia (including New Guinea), eastern China and southern Japan and eastern Australia. In the north of its range and in Australia, the bird behaves as a migratory bird, migrating to the tropical part of Southeast Asia in winter (or in the southern winter). There are 10 subspecies.
The Dollar bird is a typical forest bird that breeds in tree cavities of large tall trees.
Another great article with beautiful pictures of the bird.
That way I learn something new.