Masks and foreheads. Nape and wings. Over a couple of days I learnt to tell shrikes by these characteristics, instead of going by the tails and backs by which they are named. Darwin taught us that the gradations of Galapagos finches are evidence of evolution. I realized the central Asian shrikes are no less. The fine gradations between their plumage, and the minor differences in the feeding and nesting habits, are all evidence of evolution in the same way. The four species that I learnt to distinguish are the bay backed shrike (Lanius vittatus, an endemic native of India), the Isabelline shrike (Lanius isabellinus, whose range extends well beyond India, as I now learnt), the red backed shrike (Lanius collurio), and the red tailed shrike (Lanius phoenicurides). The last three share part of their ranges, and are called sympatric species because of that.
We’d arrived in Kutch to watch the migrations of the red backed and red tailed shrikes, little knowing that backs and tails do not really distinguish them. Out first lesson: the males of the red backed shrike (L. collurio) is very similar to the native bay backed shrike (L. vittatus). There are two things you have to look out for. The first is that L. collurio‘s eye mask narrows over the forehead but that of L. vittatus does not. The second is even more subtle: a white patch on the wings tells you that you are looking at L. vittatus. Look at the first two photos in the gallery above to see the differences (as always, clicking on a panel will take you to a full sized photo).
The featured photo shows a red tailed shrike (L. phoenicurides), but it took me some time to recognize it for what it is. Individuals can differ in the amount of red in the back and tail, and when you see lots of them together, it may get hard to tell them apart. I learnt to look at the head and nape. These are completely blue-gray in L. collurio, but have more of a red tinge in L. phoenicurides. In other words, to tell the red tailed shrike, look for a red head!
The red tailed shrike (L. phoenicurides) breeds in central Asia, through an arc from Afghanistan to Mongolia. The Isabelline shrike (L. isabellinus) has a wider range, breeding as far west as Ireland, and southwards in Asia into India. Russian ornithologists apparently distinguished between the two for quite a while, but it was only about a decade ago that West European scientists agreed to split the species. The crucial observations were the rarity of cross breeds, or, in the language of modern biology, the absence of gene flow between the two populations (note however, that there are photos of courtship between the two species). Although the two have very similar colours, the mask over the eyes of the male L. phoenicurides is definitely more pronounced. The females of both species lack the distinct mask. But both sexes have a red head in L. phoenicurides. Again, click the photos in the gallery to see the differences.
What about their behaviour? Shrikes are called butcher birds for a reason, and I saw that behaviour clearly in my first sighting of the red tailed shrike. It had just caught an insect, and was busy impaling it on a thorn. Like a butcher, it keeps a stock of carcasses. All sought out higher perches, their favourite being two to three meters off the ground. This was perfect for photography. You can see them either sitting on wires, or on thorny bushes. The latter are perfectly suited for their lifestyle. A study made almost exactly two years ago in Oman on migrating individuals of L. collurio and L. phoenicuroides could not find any differences in their foraging habits. I guess one would need a longer and wider survey to find any differences, since they are so subtle.
The immature birds present an equal challenge in identification. I eventually managed to figure out the differences between juvelines the red backed (extreme left) and the red tailed (middle) shrikes. The old rule again: look for a red head to tell the red tailed. But surprisingly we also spotted a long tailed shrike (Lanius schach). This one breeds in India and to the east, and we saw only this one specimen. So the Rann of Kutch may be on the western border of its range. Thinking of immature birds and breeding, also brings to mind the ability of shrikes to distinguish between their eggs and those of others. A recent attempt at constructing the evolutionary tree of the shrikes mentions that this may point to past brood parasitism. Cuckoos have created similar cognitive abilities in some other birds as well.
Kutch was a major learning experience for me. I’d only seen the Isabelline and bay backed shrikes earlier. They are easy to distinguish. Seeing the two passage migrants, the red backed and red tailed shrikes brought home to me how recent the evolution of the shrikes must have been. Of course, all birds that we see today evolved fairly recently. They are the remnants of the dinosaurs after all. But the evolution of some shrikes could be even more recent than of humans. That surprised me no end.