Birds in Their Habitats Read online

  Of course, such a bonanza of protein attracts hunters in vast numbers too. The locust cloud carried within it hundreds, probably thousands, of White-browed and Masked Woodswallows, gorging until they could eat no more. But if you take thousands of locusts away from a swarm of millions, you’re still left with millions … A couple of Brolgas darting to and fro on the plain were similarly overwhelmed. Above them a flock of some two dozen Brown Falcons circled and snatched. I think of these birds as being typically in pairs, and this was something I’d never seen before.

  Woodswallows and nomadism

  These two woodswallow species are as much children of El Niño as are the budgies and zebbies. There are six Australian species – one of these extends into the Pacific and South-East Asia. Despite the name, they have no relationship with swallows, but do share with them the characteristic of catching insects in the air; their closest relatives are the Australian magpies, butcherbirds and currawongs. This has only recently been accepted though: in 1973, JD McDonald, who had headed up the Bird Department of the British Natural History Museum, wrote in his Birds of Australia that ‘their connections are obscure’ (McDonald 1973). One source of confusion is their honeyeater-like brushy-tipped tongue used for extracting nectar from flowers. Back in 1907, however, a connection between woodswallows and Australian magpies had been suggested by William Pycraft of the British Museum; this was largely ignored, but eventually confirmed and extended to currawongs and butcherbirds by Allan McEvey, from the Museum of Victoria, in 1976. McEvey based his conclusions on skeletal studies (as had Pycraft 69 years previously). In particular, he noted, uniquely among Australian passerines, a shared strange extension of a cheek bone – a ‘bifurcated zygomatic process’ if you please (McEvey 1976).

  All but one of the six Australian woodswallows are found in the desert lands, but only White-browed and Masked are inveterate nomads, following the rains, the grasshoppers or other resources wherever they may lead them.

  Migration and nomadism

  True migration – the predictable annual movement of all or most of a population from a breeding ground to a warmer wintering ground – is not nearly as significant in Australia as elsewhere in the world. Yet again, the reason is El Niño: there is not much point flying 10 000 km from the far Northern Hemisphere for a warm relaxing break from breeding and finding yourself in a drought. So, although hundreds of millions of birds yearly fly between northern Europe/ west Asia and Africa, and between North and South America, the birds that breed in the endless northern forests and tundra of eastern Asia (due north of Australia) also fly south, but stop short of coming to Australia. The exceptions prove the rule – waders and seabirds whose habitats are effectively drought-proofed. (In the winter-cold south-east of the country, many species are true migrants but, having bred in the south, they only go as far as Queensland, or in a few cases to New Guinea and adjacent Indonesia.)

  A few other species undertake annual migrations that, quite frankly, seem to make no sense at all (though of course they must). A small number of tropical species – Red-bellied Pittas, Torresian Imperial Pigeons and Buff-breasted Paradise-Kingfishers, for instance – breed in northern Australia in the wet, and pop across Torres Strait to New Guinea for the dry season. Why? Conditions are near-identical. Similarly, Double-banded Plovers breed on the south island of New Zealand in summer, then make the relatively short flight across the Tasman Sea to spend the rest of the year at similar latitudes in south-eastern Australia. Again the advantages of the strategy are not obvious.

  Nomadism on the other hand – incessant wandering following rains, seeding or flowering, or just seeking them out – is a very significant part of the lifestyle of many desert species. For inland waterbirds, there is no other way they could survive.

  White-browed and Masked Woodswallows may turn up after rain in their thousands in an area they have not been seen in for years, then disappear again. Curiously, they are nearly always together, but they’re an odd couple. They have very different plumages, but to our ears their calls are indistinguishable: you might reasonably think this is just us, but more startlingly their mitochondrial DNA seems identical too. This is not supposed to happen – much more often the secrets of the cell reveal two separate species where our eyes had only recognised one. They not only look very different to us but, more relevantly, to each other as, while they regularly breed in mixed colonies, hybridisation is very rare (Joseph et al. 2006; Joseph 2009). What does this tell us? No-one seems to be sure actually (other than that they separated from a common ancestor in recent times), which I often find quietly satisfying; a bit of a reminder never goes astray about our need for more humility than we are wont to display.

  By now the great black bruised storm clouds to the north, glowing inside with near-constant lightning, suddenly burst upon us, nearly clearing the windscreen of locust detritus with hammering rain: time to drive on.

  Flock Bronzewings and Fairy Martins

  The previous day, we had been delighted to encounter another nomad a little to the east, quite unexpectedly, with half a dozen somewhat theatrical black and white faces emerging from the saltbush around a little slot dam almost on the outskirts of Windorah on Coopers Creek. ‘Theatrical’ is actually not such a bad descriptor: the Flock Bronzewing’s species name is Phaps histrionica, with histrionica being from the Latin for a pantomime performer, from its apparently made-up face. I’d never seen Flock Bronzewings so far east, but wasn’t especially surprised to do so now. These too are true children of El Niño, appearing in vast numbers in good years and spreading far across the land, studding the ground with their eggs (tales abound of sheep being stained yellow by them, after a night’s rest on the plains) then disappearing into some secret fastness. Flocks of up to a million were reported from the 19th century, but by the end of that century it was feared that they may have succumbed entirely under relentless habitat alteration, especially over-grazing by sheep and rabbits, shooting and cat and fox predation on nesting birds and eggs. By mid-20th century, they were making a recovery – perhaps related to rabbit control by the myxoma virus (i.e. myxomatosis)? – and I’ve driven through big scattered flocks in South Australia, but flocks of hundreds of thousands seem but a wistful dream now.

  Another bird found throughout the channel country seems to have done much better from human intervention. The roads of the channel country can only exist because of numerous bridges and even more numerous culverts, which might pass beneath the tyres without being noticed were it not for the whirling clouds of birds above each one. Stop and open the windows and the air is filled with the musical buzzing as even more Fairy Martins arise from beneath us. Their ancestors relied on cliffs, overhanging banks and big tree hollows to anchor their jumbled apartment cities of funnel-mouthed, enclosed mud nests. Today’s rusty-headed ‘fairies’ have a near limitless range of choices: under these bridges and culverts, and under the eaves of a million bush dwellings and sheds. The Fairy Martin is a relative newcomer to Australia – its closest relatives are found in Africa, Asia and the Americas – and it seems likely that only human assistance has enabled it to penetrate the desert lands. A relative, however, the beautiful White-backed Swallow, has its closest relatives in Africa, but has been here long enough to have truly adapted to desert living and to have evolved in different directions so that it is now recognised as comprising its own genus. It has no need of human constructions to nest, but digs its own burrows (or uses those of bilbies or rat-kangaroos) and makes a nest chamber at the end.

  The Sahel: arid woodland

  The Sahel is a vast swathe of arid woodland separating the Saharan sands from the grassy savannahs further south. Up to 1000 km wide, it crosses Africa from the Atlantic to the Indian Ocean, forming part of a dozen countries. I encountered it on a dedicated bird trip with expert guides in far northern Cameroon, from the northern regional capital of Maroua to Waza National Park. This is a distance of just 120 km, but on crumbling roads (a legacy of long-gone French and British colonial
governments and now best thought of as craters connected by remnants of bitumen), and of course bird stops, that can take hours. The few motorbikes carry up to four people – and not a helmet to be seen. Other road users include bicycles carrying almost anything imaginable, including live goats, vast loads of firewood and long bundles of reeds carried crossways, which present serious hazards. Women walk, carrying equally huge loads of wood or big earthenware pots on their heads. The level of firewood extraction is alarming, made more so by the piles by the road in villages, tied with grass for collection by semitrailers for use in towns. In such a dry climate it can’t be sustainable, spelling a grim future alike for wildlife and the people relying on the wood for cooking. It is already noticeable how much denser the thorny acacia scrubland is away from villages.

  Cameroon itself is on the cusp between west and central Africa, perched on the ‘armpit’ of Africa where the west coast suddenly stops heading north from South Africa and swings due west. Vibrant, struggling with official corruption and a president determined to hold onto power (33 years and counting as I write, but at least he was elected), crumbling infrastructure, pretty basic lifestyles, especially in the north, and environmental damage, but a country of great natural richness where people are welcoming of outsiders and Christians and Muslims seem to rub along pretty comfortably.

  When we stopped outside a village to search a big volcanic outcrop for birds, we attracted an audience – people watching the watchers. Cyclists stopped to exchange comments on us, and a gaggle of children appeared, along with a patriarchal chap in robes and spectacles, on a very little motorbike. Among the rocks, a handsome stolid Greyish Eagle-Owl, an arid land specialist, glowered at us from within a rock shelter. Further up the road, we stopped to search for a real ‘special’ though – a Quail-plover – in an unpromising-looking dry sparse shrubby landscape with a permanent haze of dust or smoke, which belied the already fierce heat of the day.

  The Quail-plover: of birding and twitching

  The Quail-plover is neither quail nor plover (Australia has a particularly bad habit of using such misleadingly chimeric names, but we’re not alone in it!). The buttonquails are a Family of birds not at all related to quails (yes, I know, but life is easier if you just accept such things), being more closely related to shorebirds, though they are certainly superficially quail-like, being small and dumpy and prone to exploding out from under your feet and disappearing again. The Family comprises 16 species of the genus Turnix, spread across much of Africa, southern Spain, south-eastern Asia and Australia, plus the Quail-plover: a single-species genus pretty much limited to the hot dry Sahel grasslands.

  The search was an interesting lesson in different approaches to birding; about half of my companions on this trip, none of whom I knew, were hard-core twitchers, men (all nine of us carried a Y-chromosome) with an already impressive list of birds from around the world and whose primary purpose in life was to add to it. Their competitiveness was mostly subtle, though not always so, and pressure on our excellent guides was always simmering. The Quail-plover was one reason for them to have come to somewhere as remote, and frankly often difficult, as Cameroon, and without seeing the bird we weren’t going to leave this harsh plain until dark if necessary – in which case we would have been back the next morning.

  I don’t regard myself as primarily a twitcher, though I make efforts to see and enjoy new birds, and keep careful lists from my travels, which I enter on databases. However, I never tire of the familiar birds either: the day I get bored with Galahs (an abundant but gorgeous Australian cockatoo) it will be time to hang up my binoculars. I couldn’t conceive of blinkering myself to the rest of nature, let alone only to birds I hadn’t previously seen. At one stage on the trip, our guide was showing me some lovely epiphytic orchids, and I heard one of our party mutter in his broad northern English accent ‘bad as effin’ Nature Trek’; it was only partly light-hearted. Were I involved with that tour company I’d have taken it as a compliment, but he didn’t intend it as such.

  For me, everything about Cameroon was new and interesting. I was revelling in that and, although I wanted to see the Quail-plover too, and joined the line sweeping the plain systematically, I made sure I was on the end. From here I could discreetly skive off from time to time to pursue such Sahel delights as Rufous-tailed and Black Scrub Robins, Chestnut-bellied Starlings, Chestnut-backed Sparrow-larks and smartly coiffured Black-headed Lapwings. Ponderously graceful White-bellied Bustards flapped off and gloriously elegant African Swallow-tailed Kites drifted weightlessly overhead.

  In the event, we did find our bird when it flushed from the ground, flying a short distance with its strange bouncy flight totally unlike the rocketing whirr of its relations. We watched it for some 45 minutes while it stayed quietly and sensibly in the shade – in direct contrast to us. When it moved on, I was glad that our guide declined to let us follow it again, so that it could get on with its life.

  At another stop, even sparser and hotter than the Quail-plover’s, we tried, this time in vain, for another Sahel special: the apparently rare and certainly little-known Golden Nightjar. Later, some of the party would make a long return drive in the evening to try again at the end of a protracted and exhausting day. I couldn’t have done it by then, and thought they deserved better success than they had.

  Waza National Park and its panting birds

  The drive up that crumbling highway was a bit of a trial (the French were building a lovely new one alongside it, which I assume is now open), but my sadness at remembering that trip now has nothing to do with the minor discomfort of the time, which has been entirely overshadowed by subsequent events. At the time, Boko Haram existed in north-eastern Nigeria, but had been quiet for a while and not generally regarded as a threat elsewhere. Then, in February 2013, a group of these insurgents crossed the nearby Cameroonian border by Waza, our destination that day, and kidnapped a French family, releasing them 2 months later amid strongly denied claims that money had been paid to the Boko Haram cause. At that moment, the trickle of visitors to the north, and especially to Waza National Park, stopped dead, and with it the small but valuable income that we were bringing the local economy. Most chillingly, in January 2015, a local bus was stopped on the stretch of highway we drove that day, and at least 11 people were murdered. It seems that their crime was to live in peace with their neighbours. I wonder what has happened to the people we passed on the roadside, the people we waved to, smiled at, bought supplies from. It will be a long time before birders pass that way again.

  Waza National Park comprises 170 000 ha of the Sahel: dry and dusty when we were there, with viciously spiny deciduous acacias above sparse dry grasses. And it was hot. Our accommodation comprised a group of basic, but comfortable, round stone cottages clustered on a stony hill at the edge of the park. We got there in the afternoon, and the heat lay on the land like a blanket. The only animals that seemed happy with the conditions were the agamid lizards that scurried about in the open-sided restaurant.

  Ethiopian Swallows sat on twigs in the full sun, under which their wing and back feathers glinted blue-black, beaks open, panting (see Photo 3). Above them a glorious White-throated Bee-eater sat doing the same. I love bee-eaters, and this one is typically splendid, with its white face between black cap and bib divided by a broad black stripe back through its eye, ochre back grading to green-blue wings, and an unusual pale aqua breast. The elegantly long tail streamers told us it was breeding. Indeed, this species flies from the great tropical rainforests south of here to breed in the Sahel, relying on the ephemeral winter rains. This seems a risky strategy but, although it is equally arid, this country has a more predictable climate than El Niño-taunted Australia. Why these birds should choose to sit out in the blazing sun is a bit of a mystery, but perhaps there was a subtle breeze – if so, it was certainly too subtle for me to detect! The clustering little tawny African Silverbills (grass-finches, or waxbills, like the finches at Warrigal Waterhole) were sensibly in the shade o
n branches of a big tree, alternately preening each other and just sitting – and panting.

  All this panting was a direct response to the heat. The original purpose of feathers, in non-flying dinosaurs, was insulation. (Later they adapted them to flight, but that is a story for another day.) Preventing loss of heat is still one of their major purposes, and by trapping a layer of insulating air they do the job very efficiently indeed. Birds don’t have sweat glands (which we use to enable evaporative cooling) – there would be little point having them under the feathers. Ours work because we have dispensed with insulating body hair. A little water can escape through the bird’s skin, but this isn’t very efficient. Perhaps the major way that birds prevent themselves from overheating at temperatures much over 30°C is by evaporative water loss through exposing the moist mouth and throat tissues to the air and breathing rapidly to create an air flow over them. Some birds step up the process by ‘gular fluttering’, rapidly vibrating the lower mouth and throat surface, including that of the upper digestive tract: pelicans and cormorants demonstrate this well. The fluttering is pushed by the bony hyoid, which supports both the tongue and the upper respiratory and digestive tubes. Because this process affects the digestive tract, rather than the respiratory one, the dangers of hyperventilation are reduced. Gular fluttering seems to be especially efficient in bigger birds. What is odd is that it doesn’t occur in passerines, which are the largest and most recently evolved Order of birds. It is unlikely that they had the ability and later lost it, so presumably the ancestral passerine hadn’t learnt the trick and it didn’t ever evolve in this Order.