passage migrant – Don't hold your breath

Living in 402

Tomorrow the day dawns on a new year: 403 ME. The last day of the year, today is an appropriate time to look back and rid yourself of ghosts. If 401 ME was the year we spent in fear, then this past year, 402 ME, was the year that the world burnt. Uncontrolled forest fires blazed through the hills and forests of Uttarakhand, and a wave of the delta variant of SARS-CoV-2 burnt through India. But the year brought its good times too: meetings with family, friends, a slow return to more regular social interactions.

It was the end of an interlude between two waves of the pandemic. We’d spent the early part of the year travelling. I have great memories of two walks during that time. One was the steep trail in Mahabaleshwar which leads from the plateau down to a lovely view of Arthur’s Seat (I don’t know who this Arthur was). The other was the a few kilometers along a historic trade route which once crossed the Himalayas and connected Bengal to Sichuan province in China, through Bhutan and Tibet. The mule you see above is one of the broken line which once facilitated this trickle of trade.

Our long-planned series of trips through the Himalayas, watching birds and following in the footsteps of the 19th century botanists was brought to an abrupt halt. Soon after we were vaccinated, the great wave of delta started. Travel was restricted again, and the trip we had planned to watch the blooming of rhododendrons in Sikkim, and the subsequent push to cross the 5000 meter mark of altitude had to be cancelled.

The end of spring and the following hottest months of year could have been the most depressing months of our lives. The sudden pruning of our circle of friends and acquaintances was drastic. It seemed like a diminished world when we could finally venture out to the Western Ghats in the monsoon. We had missed the flowers of spring in the Himalayas, but we were in time to see the great blooming of the Ghats.

European roller (Coracias garrulus) in the Rann of Kutch

Then, before you could say Sharad Ritu, it seemed that the monsoon was over and the season of migratory birds was on us. Mumbai is at the very edge of a migratory highway, and every season there is great excitement about vagrants having stopped in the city. This year we joined a group of other birders to travel into the center of the passageway, a few hundred kilometers to our northwest, to watch passage migrants crossing India. It was interesting to see exhausted European roller bird (Coracias garrulus) take a halt in their three day long flight from north west Asia to Africa. The chestnut colour on their backs and the blue in front in a complete reversal of the coat of the Indian roller bird (Coracias benghalensis).

The end of the year was a good season for travel. We were fully vaccinated, the pandemic was at a low ebb, and the weather was good. Perfect for a series of visits to nature parks (a special mention of a fantastic sighting of a clan of dholes, Cuon alpinus, the Indian wild dogs) and historic towns we had always wanted to see but never made time for. Now, as the omicron spreads, we are wondering about the best way to ride out the next year.

A Kutchi September’s shrikes

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.

Red tailed shrike, Lanius phoenicuroides

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.

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.

Blue cheeked and other bee eaters

Tolstoy may have forgotten to write “Bee eaters are all alike.” But that’s why it was not hard to tell that the birds playing possum in sand banks were bee eaters. Finally, after two days of search we saw the blue-cheeked bee eaters (Merops persicus). On the basis of genetics, it seems that bee eaters can be divided into two main clades. One consists mainly of species which nest in Africa, and the other of species that nest in Europe and Asia. The latter are mostly migratory. Climate change may be affecting these patterns (some European bee eaters, M. apiaster now breed in South Africa), but the patterns hold for most species. M. persicus is a borderline case, what Tolstoy may have called an unhappy bee eater. One subspecies breeds in north Africa (Morocco, Algeria and Tunisia) but migrates to west Africa (Mauritania, Gambia, Guinea, Sierra Leone etc) in winter. Another may be called Central Asian (since it breeds in an arc from Kyrgyztan in the north to Turkey, Greece, and Egypt in the south) and winters in east and south Africa. This was the subspecies that we had gone to Kutch to see.

There is an increasing appreciation of the European bee eater as an ecosystem engineer, since it nests in deep burrows. These serve to change the characteristics of the soil, and provides space for nesting to secondary species. In addition, their foraging provides controls insect population and provides food to other species. But these characteristics are all true of both the blue cheeked bee eater (M. persicus) and the little green bee eater (M. orientalis). A little reading convinces me that there is a case to be made for this whole genus to have similar nesting and feeding habits. So it is possible that all bee eaters could be ecosystem engineers. Certainly, studies should give interesting results. Due to their conflicts with humans in areas where bees are cultivated, this might be quite an important topic.

Having seen migrants arriving and leaving together, often flying in formation, I’d begun to think that migration must involve gregarious birds. But just the day before I’d come across a long-distance migratory bird, the rufous-tailed scrub robin, which was territorial, even for rest breaks during its migration. The bee eaters, however, are communal. A large flock was sitting on electrical wires, acacia trees, and flying down to a nearby sand bank for a sand bath. Do they fly together? I don’t know. Although seeing them taking sand baths cheek by jowl, I would think they might. They are such unlikely travellers. When you see them flying, they are on short flights, usually to catch food before returning to their perch. Here they seemed to be having fun hopping down for a communal sand bath, behaving a bit like a group of children at a swimming pool.

The whole bunch of birds had their beaks open, tongues out. Seeing one such bird supine on the ground, The Family had come to the conclusion that it was dead, and was very surprised when it flew up to a nearby tree. I didn’t notice much sound from the group, so the open mouths and wagging tongues were not producing calls. I suspect that this was their way of cooling off, much as a dog will pant to cool down. I initially thought that the dust bath was also part of their attempt to cool down. It may have been partly that, but it is more likely that this for the usual reasons: getting rid of parasites and cleaning the feathers. I haven’t noticed this behaviour amongst our resident M. orientalis, but I must look more carefully at them. Thinking of all the bee eaters I’ve seen, I think Tolstoy missed a great opportunity by not writing a sentence about the genus Merops to rival the opening of Anna Karenina.

Much confusion

You can tell that I’m not a natural born ornithologist by the fact that my first question after taking the featured photo was “What’s that bush with the white flowers?” Everyone else in the jeep was babbling about greater, lesser, and common whitethroats. The Family gave me a look which would have melted the lens in her binoculars if she’d not had to take it off her eyes in order to look at me. As a peace offering I said “Definitely a common whitethroat. See.” She looked at the photo I’d taken and said “Okay. At least you go it.” It was at extreme range, and any attempt to zoom made it a little fuzzy. October took a look and said excitedly “Clear eye ring. Obviously Curruca communis.” Wisdom looked, but reserved her judgement. I waited until I could search for a good explanation of the difference between the common whitethroat (Curruca communis, also greater whitethroat) and the lesser whitethroat (Curruca curruca). There is one, and it is worth reading.

Why the excitement? Because this is another bird of passage in India. It spends its summers breeding in Europe (every single country, including Iceland), south across Gibralatar to Morocco, and eastward in an arc over central Asia right up to Mongolia. In winter it migrated to Africa. The western population crosses the Mediterranean and the Sahara to winter in a narrow band across sub-Saharan Africa. The eastern population crosses either the Mediterranean or the central desert land (the complex of the Gobi, Thar and Arab deserts) to winter in the great rift valley and the surrounding parts of eastern Africa. For a short while the greatest density of these birds in the east is in the Rann of Kutch. We had timed our trip to catch this unique sight.

A new longevity record has been registered for the Common Whitethroat Curruca communis, with a bird recaptured in Italy 18 years and 11 months from the date of ringing. This exceeds the previous longevity record by almost 10 years.
Roberto Pollo

C. communis is very well-studied bird. Its population crashed during the great Sahel drought of the 1970s and 80s (those with long memories may remember the Live Aid concerts of 1985 in response). But the species is said to be well on the way to recovery now. I always wonder though what this means. The genetic diversity in the current population must be much reduced compared to what it was before. Would this have consequences in the coming years of a warm earth? There is evidence that the evolution and speciation of warblers was strongly influenced by climatic changes. Perhaps we are at the beginning of a burst of such speciation.

Unfortunately I got sidetracked by the interests of people around me and never got back to the question that interested me in the first place.

Long name, small bird

There, under the thorn bush. Someone whispered urgently. Yes, some movement. I looked through the viewfinder of my camera. Was it a robin? It hopped around on the ground, pecking now and then. Yes, it could be a scrub robin. And then it cocked its tail up and began to bob it. Definitely a robin. A scrub robin. A rufous-tailed scrub robin. The Latin binomial is no better. Cercotrichas galactotes. These are inordinately long names for a small and very active bird.

C. galactotes breeds in Morocco, southern Spain and Portugal, and east through an arc passing through Greece, Turkey, all the way to Uzbekistan and Kyrgyzstan. There are southern breeding populations possibly in Iran, Afghanistan and maybe the western parts of Pakistan. Throughout its breeding range the common cuckoo is a nest parasite. In winter it moves to sub-Saharan Africa. The Iberian population detours to the west before crossing the Sahara. The migration of the central Asian population goes over India and the Arab peninsula.

We saw only one individual, and it was very active. It remained in place for a long time, calling. There was an answering call but no other bird came to look for it. The call could be a territory marker; it is not a gregarious bird. Field guides tell you to look for a white edge to the tail and black markings just before it. Since we saw only one bird, I couldn’t figure out whether the absence of strong markings on the tail was an individual quirk or not. The plumage does not change with season. Nor is there sexual dimorphism in this bird. In the next couple of days we didn’t see any bird of this species again. To answer my question I had to search for photos on the web. It seems that the muted pattern that I saw is within the range of variation in the species.

A bird of passage

European rollers (Coracias garrulus) breed in a belt that extends from Spain in the west to central Asia and northern Kashmir in the east. The increasingly popular common name, the Eurasian roller, is therefore more appropriate. All these birds winter in Africa. Around this time of the year, the eastern population passes over India on its way to east and south Africa. The great Rann of Kutch is one of the places where they stop to feed before crossing the Arabian Sea into eastern Africa. These birds were visible in plenty on our visit to the Rann: sitting quietly on electrical transmission lines, poles, and tips of low trees. I could see them from break of dawn until the light faded in the evenings, sitting still.

The routes that each bird chooses are generally not known. A recent study tracked individuals which nest in southern France and found that they follow essentially a straight line over the Mediterranean and the Sahara to their wintering grounds in west Africa, making a couple of stops on the way. Different birds of the same species must have similar endurance, no matter where they nest. So I would guess that birds from the central Asian population would rest two or three times before they reach Kenya or Tanzania. Then maybe most of the birds we saw were resting after a long day’s flight. The individual in the photo above seems to have lost a lot of body mass; its body looks as narrow as its head. This stop may be very necessary for it.

The Eurasian roller is markedly different in appearance from the Indian roller (C. benghalensis). The most noticeable difference is the complete absence of chestnut colour from its breast and neck. The air was full of dragonflies, and I expected to see birds make forays to pluck a few from the air. Oddly, I saw nothing of the sort. Should one again put this down to tiredness? One summer, long ago, I’d seen a few of these birds in the swampy Camargue in the south of France. They were quite active. During breeding season they develop a prominent indigo streak below the wings, which I remember well. The winter plumage is more dull. Does that have survival value during migration? I wish I knew the answer to such questions.