by Scott Leslie
First discovered in the early 1860s, the crested tern was once widely distributed along China’s coast, as far north as Shandong Province. Until just recently, its last reliable confirmed record anywhere was from 1937, and it was presumed extinct by the late 20th century. Then, in 2000, four chicks and four adults were found amid a colony of greater crested terns, a more numerous but similar species, on an island in the Matsu Archipelago off the coast of mainland China’s Fujian Province—an area administered by Taiwan. In 2004, a few more birds turned up farther south in the Jiushan Islands of Zhejiang Province. Today, these two areas account for the sum total of Chinese crested terns in existence.
According to the IUCN Red List, the count is fewer than 50 surviving birds, though in fact, no more than about 20 birds, including chicks, have actually been counted at any one time since their rediscovery. In winter, Chinese crested terns migrate to warmer climes, where they used to be seen feeding at tidal mudflats in several Southeast Asian countries such as Thailand and the Philippines. In late 2010 on a wetland in Indonesia, a single Chinese crested tern was observed during the non-breeding season, the first record of a wintering bird in more than 70 years.
The main threat to the species now and in the past is the collection of eggs for food by fishers. This, along with hunting, is thought to have all but wiped out a once relatively common species. Ironically, the bird owes its survival at least in part to international political tensions between China and Taiwan. Fishers may have been discouraged from stealing eggs from the Matsu Archipelago tern colony because of the constant military presence in the waters between the two quarrelling jurisdictions.5 This is one case where human discord could end up helping to save a very rare living thing from extinction.
By 2000, the nesting islets in the Matsu Islands became a fully protected national nature reserve, where the Taiwan coast guard seizes the nets of any fishers caught raiding seabird colonies for eggs. The other colony in the Jiushan Islands wasn’t so lucky, however. Four of the imperilled terns bred there in 2007 and successfully laid eggs in their nests, but fishers took them all before any hatched. The Jiushan terns soon abandoned the islands (who could blame them?) and moved to a nearby nature reserve to breed, where they triumphantly fledged two young in 2009.
Egg collecting remains the most immediate threat to the Chinese crested tern’s survival—it still happens occasionally, despite the bird’s protected status. But at least it’s a problem that can be controlled through the enforcement of laws coupled with increasing local people’s awareness of the bird’s plight. What is impossible to control, however, is the widespread destruction of wetland habitat along China’s coast due to rapid economic development and the effect widespread industrial and domestic pollution has on the fish eaten by the terns.
Nevertheless, China has had some success saving endangered bird species. In 1981, only seven Asian crested ibis—a large stork-like bird—were known to exist in the wild. Today, after decades of captive breeding, reintroductions, and strict government protection of habitat, the once critically endangered bird’s population in the wild has climbed well into the hundreds. The crested tern might also someday find itself receding from the brink of extinction, the beneficiary of the same committed involvement of the Chinese government that helped the ibis. In contrast, another species in desperate need of help half a world away on politically unstable, poverty-stricken Anjouan Island is getting little support from government.
ANJOUAN SCOPS OWL
On Anjouan Island in the Indian Ocean and on neighbouring Madagascar there live two populations of identical-looking little owls—really just bundles of feathers not much bigger than a fist. One, the Anjouan scops owl, was only rediscovered by science in 1992 after an absence of over 100 years (apparently nobody had consulted the locals, who claim to have known about the bird all along). Although it had been considered one and the same as the Madagascar scops owl, the Anjouan birds are separated from the larger island by hundreds of kilometres of ocean, so biologists have suspected for some time that they might be a separate species.
So, since it is exceedingly rare, with as few as 50 pairs clinging to survival, it was important to establish the specieshood of the Anjouan bird. If it is simply a separate population of the more numerous Madagascar scops owl, its disappearance—as terrible as it would be—would result in the loss of a population rather than an entire species. If, on the other hand, it is a distinct species, it goes extinct. A big difference.
Fortunately, taxonomists are able to use DNA analysis to distinguish separate species among similar organisms. In a nutshell it works like this: A DNA molecule is shaped like a twisted ladder, a shape known as a double helix. The “rungs” of the ladder are made of paired combinations of four different chemical compounds called bases. The sequence of these base pairs along the length of the double helix will determine all the characteristics of an animal (or plant). If the base pairs of the DNA in two similar organisms don’t match closely enough, they are considered separate species. Recent DNA tests confirm that the Anjouan scops owl is indeed a separate species from the Madagascar scops owl. This puts the little bird in the unenviable position as the rarest, most endangered owl on earth.
Known to local people as the badanga, the tiny owl occurs in two colour schemes, one greyish brown, the other rufous, both of which have prominent yellow eyes surrounded by a corona of cream-coloured feathers and topped by the two small ear tufts typical of scops owls and their close relatives, the screech owls. The species’ only habitat is in fragments of undisturbed old-growth forest on steep slopes in the island’s mountainous interior. But there isn’t much of it left—only about 10 to 20 square kilometres’ worth.
Knowledge of the bird’s natural history is scant. Before its rediscovery in 1992, biologists probably missed it because of its nocturnal habits, densely forested habitat, extreme rarity, and decidedly un-owl-like repetitive pee-oo, pee-oo call, which sounds more like a shorebird’s plaintive cry. What is known is that it apparently hunts insects at night, nests in tree cavities, and roosts in dense vegetation during the day. That’s just about all that’s known of the Anjouan scops owl’s biology. It isn’t much, and with its precarious grasp on existence, there might not be much of an opportunity to learn more.
An extremely high population density of nearly 700 people per square kilometre live on the small island. The result is abject poverty and an enormous pressure on limited natural resources. The biggest threat to the owl’s survival is the ongoing loss of its remaining forest habitat for lumber, charcoal production, and agriculture. Moreover, despite its critically endangered status, it appears the species is still hunted for food. Introduced common myna birds may also be having a negative effect on the owl’s breeding success by competing for limited nesting cavity sites. Besides all that, the political stability of Anjouan is tenuous at best. After eight years of rule, a regime claiming independence for the island was ousted with bloodshed in 2008 by troops of the Comoros government and the African Union. Although elections for a new president were held in June of 2008, the political tension still runs high—not a conducive atmosphere for conservation.
There were plans to try to capture, then move, the owls to the nearby island of Moheli, but the subsequent discovery on that island of a separate, previously unknown scops owl species, itself critically endangered, scuttled the idea. The United Nations Development Programme and the Comoros government have plans to establish a protective reserve on the mountain in the centre of Anjouan, where the bird survives. Although this is a tall order when the human population itself appears to be rapidly running out of room, it at least provides a flicker of hope. Other steps such as captive breeding, the placement of nest boxes in the remaining habitat to improve the success of breeding, and working with locals on sustainable forestry plans are also being considered. But, realistically and tragically, the long-term survival of the species is a long shot.
SULU HORNBILL
Like the Anjouan scops owl, the S
ulu hornbill has the odds stacked high against it, not only because of the destruction of its habitat but also because of similar political, social, and economic conditions on its home island, thousands of kilometres distant, in the Celebes Sea.
There are 54 species of hornbills. Found exclusively in Africa and Asia, these large birds all possess one feature that sets them apart from other birds: a truly enormous bill shaped, not surprisingly, like a cow’s horn.6 As if an oversized beak weren’t enough, hornbills sport long eyelashes—actually made from modified feathers—which only adds to their whimsical appearance. From just 30 centimetres in length for the smallest forest species to over a metre for the giant ground-dwelling birds of the African savannas, hornbills span one of the broadest size ranges for any family of birds.
Most hornbills live in tropical forests, spending much of their time in the canopy exploring for fruits, large insects, small lizards, and other small animals. Despite their large, apparently awkward bills, eating small berries and insects is a breeze: grabbing an item gingerly by the tip of their huge bills, they deftly flick the morsel into the back of their throats with an upward toss of the head.
Hornbills mate for life, prompting several local cultures to consider them symbols of fidelity. Their nesting strategy is one of the strangest in the avian world. Once a pair chooses a nest site, typically a cavity in a large tree, the female enters. Using mud, fruit pulp, and their own droppings, the mated pair builds a wall over the entrance to the nest, imprisoning the female inside, where she is separated her from her mate and the outside world save for a small slit just big enough for the male to pass food through. She lays her clutch of eggs in the darkness and incubates them, all the while being fed by her mate. He also brings food to the young once they’ve hatched. When they’re ready to leave the nest, the female chisels an opening in the plaster wall, freeing herself and her offspring. Depending on the species, she may have been sequestered in the nest cavity for up to four months. Exactly why the hornbills employ such a bizarre nesting strategy is unknown, although protection from predators may be one reason.
The Sulu hornbill, the rarest of its family, lives in the Sulu Archipelago off the southern Philippines. This critically endangered bird is found nowhere else. Because it’s so scarce, little is known about its ecology, and much of its life history must be deduced from the lives of more abundant relatives. What is known is that it is a 70-centimetre-long, overall blackish bird with a dark green sheen on its upperparts and a long white tail. Sitting atop its enormous black bill is a heavy ridge known as a casque. A raucous bird whose cackling and shrieks penetrate its equatorial moist tropical forest habitat, the Sulu hornbill, like other hornbills, eats fruits, lizards and other small animals, and insects.
Fewer than 40 Sulu hornbills survive. Although it was common in the 19th century, today the species lives only on the island of Tawitawi, having already been driven to extinction in most of its former range by rampant habitat destruction on Jolo and Sanga Sanga Islands—both of which have been cleared of natural forest. And things aren’t much better on Tawitawi. Only a few hundred square kilometres of natural forest remain on the island, all of it in rugged, mountainous areas. Because such places are so hard to reach, they are usually the last to be destroyed by humans. These remnant forests are the final refuge for the Sulu hornbill. The bird needs old, large trees to survive, both for the fruit they produce and the nesting holes they provide. Unfortunately, big trees are also valuable to humans, and therein lies the crux of the problem: such value does not go unexploited for long. To make matters worse, these scraps of remaining old-growth forest are completely unprotected, and it’s only a matter of time before they are chopped down—putting the Sulu hornbill out of business for good. But that’s not all the beleaguered bird must contend with.
Armed militias on Tawitawi, warring for the island’s independence from the Philippines, thoughtlessly use wildlife, including hornbills, for target practice. If that weren’t enough, local people also invade the sanctity of the nesting birds and take the baby hornbills to eat as a delicacy; adults are actively hunted. Furthermore, Tawitawi is a very dangerous place for people. Eight villagers, including women and children, were gunned down in a local village in 2008, so it’s not surprising that conservation takes a back seat. Little has been done to save the species. The island also has a very high human population density, especially after the Philippines government forcibly resettled a quarter of a million illegal immigrants there in 2001.
What’s left of the forests must first be protected, then surveyed to establish the population and distribution of the remaining hornbills. The local public needs to be made aware that one of the world’s rarest living things lives in their midst. It’s a real uphill battle for this species, and although a difficult pill to swallow, the Sulu hornbill may be extinct very soon.
WHITE-COLLARED KITE
Every ecosystem that is under threat should have its own flagship species, a charismatic animal that can be used in the public relations battle to save it—think of the giant pandas in Chinese bamboo forests, grizzlies in the American Rockies, or the tigers in the jungles of India. It’s a way to put a “face” to a place, an important step to garnering the support needed to save habitat from destruction. The white-collared kite could play such a role for the Murici forest reserve in Brazil. One of the five critically endangered birds found there, the kite is a spectacular 50-centimetre-long forest-dwelling raptor, black and white with a white band around its neck. It is the most endangered bird of prey in South America. Possibly fewer than 50 breeding pairs survive on earth.
Given distinct species status only in 2005—before that it was considered a subspecies of the more populous grey-headed kite—the white-collared kite has been recorded just a few times at a handful of sites in the Brazilian states of Pernambuco and Alagoas, and recently in the adjoining state of Sergipe. It’s estimated that less than 1 percent of the kite’s original forest habitat remains, supporting probably no more than 1 percent of its original population.
Very little is known about this rarely seen bird. Typical of many hawk species, the white-collared kite’s call is a rapid series of harsh notes. They are also known to perform courtship flights where one bird will hold its wings above horizontal and rapidly flutter them to impress its mate. Based on the natural history of the very similar, better-known grey-headed kite, it’s also likely that the white-collared kite feeds on a wide variety of prey, including lizards, and smaller birds and their eggs. It may rear two or three young in a nest located high in the forest canopy.
The epicentre of the white-collared kite’s existence is the Murici forest reserve, which lies in Alagoas near the easternmost reach of South America, a point just below the equator where the continent bulges toward Africa. (If you look closely, you can see where this coastline would have fit jigsaw-like with the coast of Cameroon before the two continents were split apart by continental drift over 200 million years ago.)
Murici, a small patch of Atlantic coastal forest no larger than Manhattan, could well be the most important piece of real estate for its size on the planet for birds. It is the last, biggest, and withal best fragment of highly endangered, virgin northeastern Atlantic coastal forest ecosystem anywhere in South America. Though today it’s only a 6,000-hectare sliver of an ecosystem that once stretched for 1,000 kilometres, this “island” of biodiversity in a sea of sugar cane and cow pastures is nevertheless home to nearly 300 species of birds. Five of them are critically endangered, two of which, the Alagoas foliage-gleaner and the Alagoas antwren, are found nowhere else on earth. What’s more, countless plant species, including rare orchids and palms, as well as rare reptiles, amphibians, and insects, make Murici their home.
Whittled down to a nub by centuries of human activity, Murici is a calm eye of nature amid a cyclone of agriculture, logging, and development that has decimated virtually all of Brazil’s Atlantic forest ecoregion. Only 2 percent of this original ecosystem type remains. But althou
gh Murici was designated in 2001 an Ecological Station, Brazil’s highest official level of land protection, it is effectively a “paper park,” a euphemism for a place that is a park in name only; a place, owing to a lack of money or political will, no real effort is made to protect.
The case of the Alagoas curassow is a lesson of what could happen to other species if more isn’t done to protect this endangered ecosystem. The last vestige of this large ground-dwelling bird’s habitat near Murici was decimated, causing the curassow to become extinct in the wild. So, for the white-collared kite and the other critically endangered Murici birds, the only hope for survival is to stop further destruction of the forest. However, even if it was left alone and fully protected, it is so small that it might not be able to support the full spectrum of biological diversity for long. The process of exponential decay may have already begun. This occurs when small “islands” of habitat are left in the midst of a human-altered landscape. Every species has a definite minimum habitat size, beyond which it will eventually go extinct, no matter if the land is protected or not. The frequency of extinctions accelerates as the habitat patch shrinks. What the future ultimately holds for the white-collared kite will depend on how it fares in such patchy habitats, and whether more members of the species will be discovered in Atlantic coastal forest areas outside Alagoas and Pernambuco, such as those birds observed in Sergipe.