Indo-Chinese Roller: Tale of a 'new bird'
Bangladesh now boasts a new bird and even more fortunately, it is often seen in Dhaka city. The bird is not a new arrival but has recently been recognised as a new bird by scientists. The name of the new bird is Indo-Chinese Roller. It was inaccurately called Indian Roller before. We always knew that the Indian Roller, available in the west of Bangladesh up to Afghanistan, looked considerably different from those seen in the east of Bangladesh down to Vietnam.
The dissimilarity between the two groups was considered a natural variation of a single species. Recent studies, however, suggest that the two groups should be considered two separate species and be named differently. Consequently, the eastern group has been given the new name, Indo-Chinese Roller while the western group will still be known as the Indian Roller. Fortunately for us, both the species are found in Bangladesh, unlike most other countries. For this country, therefore, the Indo-Chinese Roller is indeed a new bird out of an old stock.
The list of the country's fauna is now enriched by an additional bird. However pleasing that may be, it has not made the lives of bird-watchers any easier. In the good old days, they could call anything that looked like a roller an Indian Roller without paying too much attention to its plumage's colours. Now they must note the colours and the hues of every roller carefully to tell if it is an Indian Roller or an Indo-Chinese Roller. All the differences between the two species are there in the plumage pigmentations only; not in size or shape.
The photographs provided here should help readers to distinguish between the two species of rollers. The Indo-Chinese Roller was photographed at Purbachal and the Indian Roller was photographed at southern Faridpur. The former generally appears darker than the latter. The Indo-Chinese roller has markedly brighter blue feathers above its bill and on the forehead; and with a long dark line above the eye it appears to be ceaselessly frowning at on-lookers. It is easier to tell the two species apart by noting the colour patterns of their tails. The Indo-Chinese Roller has a turquoise band at the base of the tail as well as turquoise coloured outer tail-feathers. While flying, it appears to have two turquoise-blue inward-looking right-angle triangles at the tail-end. The tail of the Indian Roller, on the other hand, has a deep-blue terminal band instead.
This colour-guide to the two species of rollers cannot be complete without a disclaimer: The two species being very closely related, they sometimes interbreed birthing chicks of a confusing mixture of colours. The birds with mixed features, however, need not annoy anyone except the people estimating the population of the two species of rollers in Bangladesh.
Carl Linnaeus, the great inventor of binomial nomenclature, named the Indian Roller Coracias benghalensis, presumably because he received the first specimen of the bird from Bengal. Not surprisingly, therefore, the species has been named 'Bangla Neelkanto' in the Bengali version of the Encyclopedia of Flora and Fauna of Bangladesh published in 2009. Now the Indian Roller is split into two species; and the new species, the Indo-Chinese Roller, has been named Coracias affinis. What the next edition of Bengali Encyclopedia would name this bird is anyone's guess. Could it be 'Chinvaroti Neelkanto'?