A sedentary acrobat! Really?

Indian roller bird in Pench National Park

Several times in my forays into Pench National Park, I noticed a bright blue flash of wings at the edge of dusty meadows full of dried grass. If I’d seen this colour near a pond or soak, I would have thought of a kingfisher. But in this habitat it was the Indian roller bird, Coracias benghalensis. True to its name it twisted and rolled in soaring flight each time I saw one. The spectacular flight is a mating display; something that is visible during its breeding season, between March and July. Unfortunately, the camera I had with me compensates for its enormous zoom by an equally enormous shutter lag. This rules out taking photos of such displays.

In any case, I was at first very surprised to find a paper which reported that roller birds were observed to spend 90% of their time sitting, at all hours of the day. It seems that foraging and feeding took substantially less than 10% of its waking hours. Such a lucky bird!

The time spent foraging may depend on the kind of terrain the bird is seen in. In the agricultural land where the study was performed, rollers were found to eat insects almost exclusively. However, in the wild it is known to prefer lizards and frogs, and sometimes is even seen eating small snakes. The larger prey may keep the bird full for a longer time, but it may also change the amount of time spent foraging before it feeds.

On second thought, I should not have been very surprised when I found that the roller is a sedentary bird. After all, I have so many photos of a roller perched somewhere (the photos here are examples). Indian roller bird in Pench National ParkOnce you get one in your viewfinder, you can go on taking photos to your heart’s content. With its wings closed it will seem to be largely reddish brown, with the blue colouring appearing only on the head, tail and part of the chest. In the 1930s, the Indian physicist C.V. Raman studied the blue colour of the roller’s wings and found that the colour was due to double scattering of light from the feathers of the bird, and not from a pigment. He moved on to study the blue colour of the sea, and won a Nobel prize for that work. Today, the nano-structures on the feathers of the roller that produce the colour are very well understood.

The Indian roller is not a threatened species. It is seen over all of India and south-east Asia, and westwards along the Arabian sea and the Gulf of Iran. Dedicated bird-watchers ignore sightings of the roller, and would roll their eyes if they saw me taking photos of one. But recent fossil finds suggest that about 30 million years ago its ancestors were spread even more widely across the world. Ancient climate changes then seem to have restricted the populations of roller birds to (roughly) their present geographical range. There are such wonderful histories behind every bird!

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Author: I. J. Khanewala

I travel on work. When that gets too tiring then I relax by travelling for holidays. The holidays are pretty hectic, so I need to unwind by getting back home. But that means work.

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