Don’t judge a bird by its cover

A small, nondescript bird. Easily spotted sitting on exposed high ground. Unremarkable call. What’s the fuss about spotted flycatchers (Musciapa striata), you may ask. I didn’t see it in the field either, when I took several photos of this bird. But consider this. The bird is less than 20 grams in weight, smaller than 15 cms in length. Despite that, the individuals that I saw were on an annual journey from Mongolia to Tanzania. I couldn’t think of walking that distance! It isn’t an easy life, not many birds live longer than a couple of years, although they are known to be able to live as long as eight years. And if that wasn’t enough, they raise two broods a year, all within the space of three months.

M. striata breed in Europe as far north as Sweden and Finland, and even across Gibraltar in Morocco and Tunisia, and in an arc north of the Caspian, eastward into Kyrgyzstan and Mongolia. The western population spends most of the year in sub-Saharan west Africa; the eastern population in east and south Africa. In September you can see it pass over a swathe of land that includes Turkey, Georgia, and western India. This little bird had drawn us for a couple of days to the Rann of Kutch.

I was very happy to be able to photograph it when some of the other birds gave me a hard time. Once you found its perch, you could be sure that it would return there after a sally. I didn’t get to see its prey. The air was full of large dragonflies. They couldn’t possibly be swallowing them on the fly. So maybe they were picking out something smaller, or maybe I just happened to miss them feeding. If the latter, then they seem to miss an insect on most of their hunting sallies.

A study showed that they are able to tell the difference between their own eggs and eggs of other species introduced into their nests. This marks it out as fairly special, since most birds are unable to do this. This ability has been interpreted as the result of a past evolutionary arms race where the ability to distinguish eggs evolved in response to nest parasitism by cuckoos. Support to this idea is given by the fact that currently parasitized species are able to distinguish eggs with some, but lesser success. The group also tested whether such an ability to distinguish eggs is related to special discernible patterns on the eggs. The lack of visual patterns shows that it is cognitive abilities which have evolved, and not egg shape, size, or colour. It is interesting, though, that the birds are not able to distinguish between their own chicks and chicks of other species placed in their nests. As Mullah Nasruddin pointed out, it doesn’t do to judge a person by their coat.