by Scott Leslie
Once the rats, cats, goats, and other introduced animals that wiped out the mockingbird on Floreana in the first place have all been removed, the reintroduction of the species will proceed, helping the Floreana mockingbird’s chances at surviving well into the future.
MANGROVE FINCH
Though we now understand that the mockingbirds of the Galapagos were the more important inspiration for the theory of natural selection, “Darwin’s finches” did nevertheless play a role in the refinement of his ideas. They’ve also inspired scientists after Darwin, such as biologist David Lack, who used his studies of the finches in the mid-20th century to fill in some of the technical details of evolution that Darwin missed.
Splitting into new species as they adapted to new ecological niches throughout the archipelago over generations, 13 finches would ultimately evolve from one common ancestor.
All quite similar in that they are “LBJs” or little brown jobs, the Galapagos finches are pretty plain birds. Plain, that is, except for the beak, which needs to be well adapted to the surrounding environment for a bird to efficiently feed itself. Some of the finches’ beaks are short and thick for cracking hard seeds, some are long and thin for reaching into flowers to sip nectar, others are pointed and of medium girth for grasping cactus spines as tools to dig beetle larvae out of rotten wood. None of the finches is abundant, living as they do in specialized habitats on relatively small islands, but by and large they’ve fared quite well. Except for one. The mangrove finch, one of the two tool-using birds on the islands (the other is the very similar woodpecker finch), has become very rare.
Found nowhere else in the world, this 14-centimetre-long brown and beige songbird once lived throughout the coastal areas of Isabela Island and neighbouring Fernandina Island. Inhabiting dense, drier stands of mangrove trees, the mangrove finch feeds on insects, worms, spiders, and grubs it gleans from shoreline leaf litter that has yet to be washed out to sea by the tide. By the 1970s, the bird was gone from Fernandina. Now teetering on the brink of extinction with fewer than 100 left, it is found only in three small patches of mangroves on Isabela, its known habitat totalling just one square kilometre.
While loss of habitat isn’t a pressing issue, since all of it is protected as part of Galapagos National Park, rising sea levels caused by climate change could affect the suitability of the dense groves of mangrove currently inhabited by the finch. As the sea creeps inexorably higher up the shore, there’s a risk that the leaf-litter environment favoured by the birds will become too wet for feeding (no longer drying out at low tide). Of more immediate concern, however, is the black rat, the enemy of island birds everywhere. These rodents—and to a lesser extent introduced feral cats and introduced smooth-billed anis, a blackbird-like species with a grotesque beak—have decimated the finch’s population by preying on eggs and nestlings.
What’s more, a tiny invader from the South American mainland has emerged as a major new threat to the mangrove finch. The larvae of a species of fruit fly known as Philornis downsi—which probably got to the Galapagos in a shipment of fruit—now infests all of the mangrove finch nests (as well as many nests of the other finch species on the archipelago). These unsavoury parasites, which suck the blood of nestlings, killed their first mangrove finch in 2007. Finding out how to stop them is a conservation priority. One idea is to breed a genetically altered sterile version of the fly that would then be released to mate with and sterilize the rest of the population. Whether this will work is anybody’s guess. And as if all that weren’t enough, the first case of avian pox, a disease that could potentially cause big problems for the vulnerable species, was recently recorded.
Despite all of this, the recovery of the species has enjoyed modest success. A program to control rats has worked quite well: fledgling survival went from just 6 in 2006, when the rat program started, to 17 a year later. It’s hoped that as more young are successfully fledged they will naturally begin to move to new habitat. This might already be occurring, as yearling finches have been observed moving about in mangrove trees outside their traditional home range. Moreover, as the population of young birds continues to expand, it is hoped some of them can be captured and relocated to suitable habitats that have been identified on the other side of Isabela. In 2010, nine birds were part of a trial relocation to new habitat on Isabela.
Remember that closely related tool-using species the woodpecker finch? Not wanting to risk experimenting with the highly endangered mangrove finch, scientists are using some of these other birds in captive breeding trials in order to develop techniques and experience that could be applied to a future mangrove finch breeding program. The ultimate goal is to increase the population enough to one day reintroduce the mangrove finch throughout most of its former range. Fortunately, DNA tests show the species still has enough genetic variation to grow and survive, so a captive breeding program should have a fair chance of succeeding.
NICEFORO’S WREN
As fascinating as the avian life is on oceanic islands like those of the Galapagos or Tahiti, these generally aren’t the best places to see a big variety of birds. If you want that, go to Colombia. With nearly 1,900 species, it has more of them than anywhere else, about one-fifth of all the birds on earth (by contrast, Canada, with a geographical area about 10 times the size, hosts only about 500 species). There’s just something special about the combination of diverse forest habitats found in the deep Andes mountain valleys and the equatorial climate that drives avian variety. What’s more, Colombia boasts 74 bird species found nowhere else in the world, the rarest of which is the Niceforo’s wren.
This small, rufous and white songbird with a thin, slightly down-curved bill and nearly vertical, skyward-pointing tail lives in an Andean valley of dry tropical forest in north-central Colombia. It was discovered by Brother Niceforo Maria, a Frenchman formerly called Antoine Rouhaire, who travelled to the country as a Catholic missionary in 1908. He went on to become one of the leading naturalists in his adopted homeland, founding the natural history museum in Medellin in 1911 and helping to discover many animals new to science. Based on specimens he collected and provided to museums around the world, scientists were able to describe over 150 new species, including 13 mammals, 14 amphibians, and 8 birds. In recognition of his contribution to science, 4 of these species have been named in his honour: Niceforo’s big-eared bat, Niceforo’s marsupial frog, Niceforo’s pintail duck, and the wren.
In the 1940s, Niceforo discovered his wren in dry tropical forest in a valley on the west slope of the Andes, not far from the Venezuela border. It then disappeared for a half century before turning up again in 1989. That it took so long for another to be recorded isn’t surprising, considering just how tiny its range and population was. It lived in just one valley, the Chichamocha. Niceforo’s wren had become legendary as South America’s rarest, most endangered bird. Today, around 20 birds are found at the original site, along with very small populations at two other nearby sites. Only about 77 birds are thought to exist.
Niceforo’s wren was probably never common. This is not particularly unusual for organisms living in tropical regions with high biodiversity where the cost of great variety is a relatively small population for any given species. That’s the polar opposite (pardon the pun) of high-latitude ecosystems that host only a few species but at very large abundances—think caribou in the Arctic or penguins in Antarctica. However small the wren’s population might have naturally been, its current numbers are far below that which are sustainable over the long term.
Once again, it appears habitat loss is playing the major role in propelling a species toward non-existence. Niceforo’s wren depends on a dense undergrowth of perennial vegetation on the forest floor. This rich understorey has been largely destroyed by centuries of grazing by goats and cattle. Much of the forest has also been cut down to make way for coffee, plantain, and sugar cane plantations.
There was very good news for the endangered bird in 2009, though. With support from the America
n Bird Conservancy, the World Land Trust-US, and the local government, Fundación ProAves, a Colombian bird conservation group, purchased 1,400 hectares of the prime wren habitat and established the Niceforo’s Wren Natural Bird Reserve. Not only did this create a safe, protected home for one of the world’s rarest birds, it preserves a slice of dry tropical forest, one of the world’s rarest ecosystems. Two other highly endangered birds, the chestnut-bellied hummingbird and the Apical flycatcher, also found in the reserve, will benefit as well. No doubt, Brother Niceforo Maria would have been pleased.
As rare as Brother Niceforo’s lovely wren is, it has nevertheless been well studied in recent years, something that can’t be said for the rather mysterious Carrizal seedeater, one of the world’s least-known birds, living just across the border in neighbouring Venezuela.
CARRIZAL SEEDEATER
Can a species go extinct before it even becomes a species? This is precisely what nearly happened to one South American bird. In 2001, Edelca, the state-owned electric company in northeastern Venezuela, commissioned a survey of wildlife in areas that would be affected by the construction of a new hydroelectric dam on the Caroni River. While surveying Isla Carrizal, an uninhabited, spiny bamboo–covered island located in the middle of the massive river, biologists discovered a songbird that had never been seen in this part of South America before. They didn’t know if it was new to science or one of several seedeater species that also lived in other parts of Latin America.
By the time it was announced in 2003 that the bird was, in fact, a unique species never seen before, it looked like it was already too late: Isla Carrizal, the only known home of the newly named Carrizal seedeater, had been destroyed, its vegetation completely razed during the development of the hydro dam. The little bird had apparently become extinct even before it officially existed; it was a birth announcement and obituary all rolled into one. Alas, and happily, reports of its demise were premature.
Small even for a songbird, the Carrizal seedeater reaches a length of only 12 centimetres, about the size of an American goldfinch. The males are a glossy blue-black with bright blue shoulders and black wings, and sport a relatively large, cone-shaped bill, typical of a seedeater. Females are light brown.
Even though the ecosystems along the Caroni River had been fairly well explored over the years, the Carrizal seedeater might have remained unknown as long as it had because it spent most of its time in groves of spiny bamboo. Growing in dense stands and wielding long, razor-sharp thorns, spiny bamboo can be a nasty weapon against large, soft-skinned mammals like humans. Living in such a fortress of inaccessibility, it isn’t surprising nobody had become acquainted with the Carrizal seedeater earlier. Because of this, of course, very little is known about its ecology, although we do know that its bill is adapted to feeding in a bamboo habitat and it may eat weevils that are associated with the giant grass.
Surveys of the Caroni River Basin in the vicinity of Isla Carrizal in 2007 and 2008 found the birds in several locations. This is obviously good news; however, it appears the surviving population is still very, very small, estimated at fewer than 50 in total. To make matters worse, none of the species’ known range is protected, a crucial step that’s needed to ensure its survival. Although it will be a challenge to save the Carrizal seedeater, searches for more of its potential habitat along the Caroni and nearby Orinoco River are planned. But even this won’t be easy, since the bird’s preferred habitat of spiny bamboo grows beneath the dense forest canopy, so it can’t be seen during aerial surveys. The challenge to save the Carrizal seedeater is made much more difficult because it’s so hard to find. Bali mynas, on the other hand, another of the rarest songbirds on earth, are threatened with extinction in part for the opposite reason: they are simply too easy for the wrong people to find.
BALI MYNA
There are few birds on earth more distinctive than the Bali myna (also known as the Bali starling). It is snow white—a rare colour for a songbird. Black wing tips and tail contrast with the pure brilliance of its body. A bright blue mask, the shape of a falcon’s wing, wraps around the eyes, and its head is topped by a drooping crest of long, delicate feathers. About the size of a northern cardinal, its natural habitat is the lowland rainforest along the northwest coast of the island of Bali, in Indonesia. In fact, the Bali myna is the only endemic species that still survives on the island (unique to Bali and found nowhere else). The only other species known to be endemic to the island was the Bali tiger, which went extinct in 1937. Destruction of the forest for agriculture and wood decreased the myna’s total habitat from about 30,000 hectares in the 1920s to about one-tenth that today, all of it inside Bali Barat National Park. But habitat destruction is only a part of the troubles faced by this species.
Like so many desired objects, the Bali myna has a beauty that is uniquely its own—a beauty that unfortunately also excites the greed of collectors of rare wild birds. As the official bird of Bali, for some Indonesians it is an “object” of status, a symbol of power and wealth. The demand for it has boosted the amount it fetches on the black market for caged wild birds, contributing greatly to its decline. Although trade in the species became illegal when it was listed under the Convention on International Trade in Endangered Species in 1970 (an international agreement regulating trade in threatened animals and plants), collectors in Bali and Java still pay poachers thousands of dollars to own one. Extreme rarity (that is, proximity to extinction) only adds to the cache of owning one. The illegal bird trade, and to a lesser extent the destruction of the bird’s natural habitat, has made the Bali myna one of most endangered songbirds. Nobody knows for sure how many there are, but it is thought anywhere between zero and about 24 birds survive in original, natural habitat.
Like other members of the starling family, the Bali myna has a rich and varied vocal repertoire and can mimic human speech.4 The myna’s best-known call is a chatter song, but it also whistles, squawks, chortles, and warbles its way though life, either in small flocks in the non-breeding season or with its mate while nesting.
To attract a mate, a male Bali myna will approach a female with his crest raised as he bobs his head up and down and makes clucking sounds. If all goes to plan, the female will requite his love by perching beside him while they perform a duet of bobbing and singing. Like other members of the starling family, abandoned tree holes that have been excavated by other birds are used for nests. The female will lay two or three eggs twice a year. Although two sets of chicks are produced annually, the species was probably never abundant.
With so few birds remaining in the wild, captive breeding and release has become the only alternative for the self-sustaining survival of the species in natural conditions (hundreds of birds live in captivity throughout Indonesia and the rest of the world, many of them poached wild birds). Although the Bali myna has proved to be relatively easy to rear in captivity, it has been much more difficult to control the dark side of human greed.
Because the bird is worth so much money on the black market, theft by poachers is a huge problem that has largely stymied efforts to ensure its survival. Case in point: in 1999, 39 birds were stolen from the breeding facility in Bali Barat National Park just before they were to be released into the wild. A well-organized armed gang tied up the guards who were supposed to be protecting the birds and stole their guns. The poachers apparently had inside information, since they knew the specific cages of the birds that were awaiting release. The bandits escaped in a boat across the narrow Strait of Bali to the neighbouring island of Java. In a suspicious twist (another hint of an inside job), the stolen guns of the guards were mysteriously returned to the breeding facility in a cardboard box a month later.
Poachers also routinely enter Bali Barat National Park at night and capture birds that have already been released. Over the years, several separate attempts at preventing the disappearance of the Bali myna have been foiled by such criminal activities.
Clearly, a different approach to saving the bird was needed
. So, in 2004, the Begawan Giri Foundation (now the Begawan Foundation) for the conservation of the Bali myna and the Friends of the National Parks Foundation began to release captive-reared birds into the wild on the small island of Nusa Penida, located off Bali’s coast. Nusa Penida was chosen because many of its communities still followed traditional laws against killing birds, and these are taken very seriously on the island. If the mynas could successfully breed in the wild on the island, then perhaps there would be a chance that the local inhabitants would protect them against poaching. The program was spearheaded by Bayu Wirayudha, a Bali native, avian veterinarian, and myna breeder. His experience told him that the species was relatively easy to breed and adaptable in the wild.
Although the release of birds into the wild on Nusa Penida was criticized by some because it is not the traditional habitat of the Bali myna, the proponents of the program argue that it may be the last hope for the bird to survive anywhere in the wild. So far it appears to be working. At last report, of the 65 birds released onto Nusa Penida by Wirayudha and his collaborators, 45 have bred and hatched offspring, helping pull the wild population of the species back from the brink of extinction.
Perhaps the Bali myna will survive somewhere in the wild after all. Unfortunately, for a delightful yellow songbird half a world away in the United States, such hope is very slim.
BACHMAN’S WARBLER
Warblers are most aptly named. In wooded habitat across North America, from great forests to small thickets, untold millions of them tirelessly warble, whistle, lisp, and chirp their way through spring and summer. And if their melodious songs weren’t enough, their brilliant, often beautifully patterned plumage offer a palette’s worth of colour: reds, yellows, oranges, greens, blues, black, and everything in between, there for the enjoyment of anyone willing to look. As Thoreau put it: “They are of every hue. Nature made them to show her colors with. There are as many as there are colors and shades.”