100 Under 100

by Scott Leslie

  Spix’s macaws live in open, dry woodland near rivers and streams dominated by caraiba trees, whose cavities they use for nesting. The female lays two to three eggs and incubates them for about four weeks, all the while taking food brought to her by her mate. Males continue to feed the mother and chicks once the eggs have hatched. Most of their diet consists of the fruit of just two local plant species. This pretty much sums up what has been learned about the lives of Spix’s macaws in the wild. However, careful observation of the trio of macaws couldn’t save them: they disappeared a few years after their discovery, possibly victims of poachers.

  Another Spix’s macaw wasn’t seen in the wild until 1990, when a lone male turned up. He was dubbed by the media as “the loneliest bird in the world.” Oddly enough, he was paired with a female blue-winged macaw, a closely related species, so amorous urges apparently hadn’t diminished. Of course, it was an unproductive pairing: the two separate species couldn’t successfully breed. Five years later, a captive female Spix’s macaw was released in the male’s territory as a potential mate. The two birds took a liking to one another and apparently paired up. It was to be a short romance: the female disappeared several weeks later, the victim of a suspected power-line collision. Alone again, the male then rekindled his Platonic relationship with the female blue-winged macaw. He was last seen in late 2000. He was the last of his kind ever seen in the wild. You can blame habitat destruction and the illegal bird trade. Africanized bees may have also played a small role, since the aggressive insects compete for the tree cavities that macaws nest in and will swarm the birds.

  Because not all of its potential habitat has been surveyed, Spix’s macaw is listed as critically endangered on the IUCN Red List, though the odds are strong that it is now extinct in the wild. There have been occasional unconfirmed sightings of the bird, particularly in the Serra da Capivara National Park, not far from where the last male was seen in 2000. This national park has a considerable area of caatinga dry scrub habitat that Spix’s macaws are known to inhabit. It also happens to be the location of one of the earliest human settlements in South America at 25,000 years old. Despite such reports, doubt nevertheless remains that the bird survives in the wild there.

  The fate of the species comes down to the success or failure of a captive breeding program. In 2010, the official number of birds in captivity stood in the seventies, most of them located in the Middle East at the state-of-the-art Al Wabra Wildlife Preservation in Qatar, while the remaining ones are divided among facilities in Brazil, Canary Islands, and Germany. The 20-year recovery plan for the species—out to 2030—hinges on a continued increase in the number of captive birds and the securing of suitable native habitat in Brazil. The gradual release of birds back into the wild will eventually follow. Gathering more complete scientific knowledge of Spix’s macaw and continuing to educate local communities about the endangered bird are important steps in the recovery. Happily, about 2,800 hectares of habitat have recently been acquired in two parcels in the last known stronghold of the bird, near Curaçá, Bahia State.

  A hemisphere away, the Hawaiian crow also has a tiny population numbering in the seventies that is hanging onto existence by a thread.

  HAWAIIAN CROW (‘ALALA)

  At one point, there was no place quite like Hawaii for crows. Fossil evidence shows that, over time, these large black songbirds evolved into separate habitat niches across the small archipelago, ultimately producing at least five species in a blossoming of adaptation nearly rivalling that of Darwin’s Galapagos finches. Like the finches, each of these crows had a specialized bill adapted for a specialized feeding niche. Given the islands’ small area of only 28,000 square kilometres (nearly identical to Massachusetts), the diversity of crows was remarkable. By comparison, the entire North American continent today has only six species of crows and ravens.

  Unfortunately, the arrival of humans in Hawaii 1,500 years ago marked the beginning of the end of this flourishing diversity. It isn’t known exactly what happened to the archipelago’s crows, but by the time Europeans arrived in the late 1700s, there was only one species left, the ‘alala.

  One of Hawaiian culture’s most sacred animals, the ‘alala is believed to escort the dead to the afterlife. By the mid-20th century, it was well on its way there itself, surviving only in very small numbers in cloud forest on the slopes of the Mauna Loa volcano on the big island of Hawaii. Why the species’ population dwindled so drastically isn’t known, but diseases such as avian malaria and fowlpox are the likely suspects.

  By the mid-1970s, with the ‘alala approaching imminent extinction, biologists captured some of the last wild birds to begin a captive breeding program. Early on, the program had little success, producing few new birds. Also not helping the beleaguered crow’s cause was an ill-conceived project in the late 1970s by biologists to learn more about the breeding and nesting behaviour of the species. Thinking it might help them solve the puzzle of its decline and better manage its recovery, they set up time-lapse movie cameras at several of the remaining ‘alala nests to film them during their breeding season.

  Any long-term intrusion into the private lives of wild species, especially endangered ones, is a risky business that should demand sober second thought before undertaking. Despite strong anecdotal evidence that the birds abandon their nests when closely observed, and an earlier case where a remote camera at a nest resulted in a nesting failure, the project went ahead. As it turns out, those red flags should have been heeded. Eleven pairs of nesting birds were filmed and, sure enough, several of the nests were abandoned. Only about 20 ‘alala were left in the wild by the time the study ended in 1980. Whether the film cameras’ proximity to the nests and their noise were responsible for the nesting failures will never be known, but it seems a safe bet. Ultimately, it may have made no difference to the fate of the crow, but the lesson taken from the failed experiment is: Sometimes the road to oblivion is paved by good intentions. Conservationists are human, and occasionally in their haste to help, they do more harm than good.

  A dozen years passed, and in 1992 there were only 11 ‘alala left in the wild. At this point, biologists wanted to capture some of those last few wild birds and place them in the captive breeding program. Did the birds stand a better chance out in nature, or in captivity? It was both a scientific and a moral dilemma. The scientists already knew that the current captive breeding program, in place since the 1970s, didn’t work very well (by 1992, only six birds born in captivity survived—not much to show for 16 years of work), but on the other hand, how could they stand by and possibly let the bird go extinct in the wild by letting nature took its course? As it turns out, they didn’t have to decide.

  Because the ‘alala is on the endangered species list, and the US Fish and Wildlife Service was desperate to find a way to save the it, the service asked the independent Washington, DC–based National Research Council Board on Biology to make suggestions on what should be done. The board recommended not capturing the wild birds. Instead, they suggested removing their eggs and artificially hatching them in a better-staffed and better-funded breeding program. They would then be released back into the wild when they were old enough. Part of the plan was that once their first clutch of eggs were removed and artificially reared in captivity, the wild birds would lay a second clutch, thus doubling their reproductive output. (This approach was nothing new; it is similar to the technique used in the recovery of the endangered Chatham Island black robin and the California condor.) And it almost worked for the ‘alala. By 1999, this new approach had added over 40 captive-hatched birds. Twenty-seven of them were released into the wild. All but 6 eventually perished because of poor habitat, disease, or predation by Hawaiian hawks. The rest of the introduced birds were recaptured. That was the end of the program. The recovery of the ‘alala was proving intractable, despite best efforts.

  By 2002, the last two ‘alala in the wild, a mated pair, died, making the bird extinct in the wild. Not all is lost, however. In 2009, t
he US Fish and Wildlife Service announced plans to restore the ‘alala back into the wild one day, primarily by protecting and improving habitat and by controlling threats to the species. By late 2010, owing to a lot of time and effort put in to a new and improved breeding program, the captive population of the ‘alala stood at 77 birds. It is a move in the right direction for the eventual rewilding of this intelligent bird.

  GUAM RAIL KO’KO’

  Like the ‘alala of Hawaii, the Guam rail is protected under the US Endangered Species Act by virtue of Guam’s status as a territory of the United States. Also known as the ko’ko’ in the local Chammoro language, the rail is a small, chicken-like bird that was once so abundant on the small tropical island in the South Pacific that it was widely hunted for food with little impact on its population. Even as recently as the late 1960s, there may have been 10,000 of them left. Tragically, the Guam rail has nearly been done in by the same thing that wiped out the Mariana fruit dove, the Guam flycatcher, the rufous fantail, the cardinal honeyeater, the white-throated ground dove, the nightingale reed-warbler, and not quite yet the Mariana crow. That thing is Boiga irregularis, a native of mainland Australasia. The brown tree snake, a voracious, invasive species, first arrived in southern Guam hidden in ships’ cargo. From there, it pushed its way north across the island. An efficient climber, it devastated bird nestlings and eggs not only on the ground but also up in the trees, leaving big holes in the avian ecosystem in its wake. It’s not surprising Guam’s forest birds had little defence against the marauder: until Boiga irregularis arrived in the mid-20th century, they had never seen a predatory snake.

  By the early 1980s, there were only a handful of ko’ko’s left. In 1983, a captive breeding program was begun, spearheaded by a Guam biologist named Bob Beck. Twenty-one birds were taken into captivity; the future of the species would depend on them. They were captured just in time, for just two years later, in 1985, the last wild-living rail was collected on Guam’s Andersen Air Force Base. With that, the ko’ko’ became extinct in the wild.

  Rails are a group of birds that generally live in wetlands or grassy areas. The phrase “skinny as a rail” is in reference to the birds’ narrow stature, which enables them to navigate among the tightly bunched reeds and grasses of their native habitats. The ko’ko’ is a medium-sized ground-dwelling bird, about the size of a bantam chicken, with a brown head and neck and a black belly with bold white barring. Its eyes are a brilliant red. Although they are essentially flightless, ko’ko’s are very quick runners; they were often seen early in the morning scurrying into the tall grass along roads, where they were feeding on a diet of insects, snails, geckos, skinks, and seeds. The rails were once abundant enough to be an annoyance to some people, as many of the birds would noisily chime in on a repetitive chorus of kee-you, kee-you; usually one bird would begin with an alarm call, only to trigger others within earshot. A year-round breeder, it generally lays between two and four speckled eggs in a shallow cup woven of grass and leaves. The downy chicks leave the nest after just one day, continuing to be fed by both parents. Of course, since the ko’ko’ is a ground-nesting, flightless bird, its eggs and chicks are also vulnerable to other invasive species besides the tree snake—feral cats and monitor lizards, for instance. Both of these have also eaten their fair share of the rails, albeit nowhere near as many as the snake.

  With no birds left in the wild, the recovery effort for the ko’ko’ came not a moment too soon. Eventually, 17 American zoos were also involved in the program. Despite breeding at only four months of age, and laying up to 10 clutches of eggs per year in captivity, the actual increase in the number of rails would take time. It wasn’t until 1989 that the first ko’ko’s were introduced back into the wild on Rota, a small, snake-free island about 70 kilometres north of Guam.12 The release of rails on Rota took place over a 10-year period. Today, it’s thought that there are between 60 and 80 birds living on the island, yet questions remain whether they can sustain themselves over the long term.

  Unfortunately, attempts at getting the birds back to the wild on Guam itself have met with failure. The survival of 16 and later 44 birds released on parcels of land protected by snake barriers on Andersen Air Force Base in 1998 and 2003 was thwarted by feral cats, which eventually killed all the rails. But the ko’ko’ and the people trying to save them aren’t giving up easily.

  As it currently stands, there are about 100 ko’ko’ at the breeding centre on Guam and 35 additional birds in US zoos (these numbers do not include the wild-living birds on Rota).

  In November 2010, 16 birds, individuals known to be strong breeders, were released onto snake-free Cocos Island, a 34-hectare atoll located two and a half kilometres off southwest Guam. This island—one-third state park, the rest a privately owned resort whose owners are working in cooperation with the government on the project—is already home to several reintroduced Guam species that have been extirpated from the main island. It is hoped that initially at least six pairs of rails will breed on the island.

  PINTA ISLAND GALAPAGOS GIANT TORTOISE

  “I frequently got on their backs, and then giving them a few raps on the hinder part of their shells, they would rise up and walk away—but I found it very difficult to keep my balance.”13 Even the most serious Victorian naturalist became playful in the midst of the otherworldly wildlife on the Galapagos Islands. This image of a giddy Charles Darwin broncobusting a giant tortoise speaks volumes about how novel these remarkable animals are.

  Among the largest reptiles in the world, Galapagos giant tortoises can weigh over 225 kilograms and possess a shell that spans over one and a half metres. The subtle physical differences between the 11 closely related subspecies, which are distributed among varied islands and habitats across the archipelago, would play a future role in Darwin’s theory of evolution.14

  Years after leaving the islands, Darwin saw the differences in the tortoises as adaptations to the unique environment of each island. For example, tortoises living on low-lying, relatively barren islands with little vegetation had to reach high overhead to get what few leaves there were. The shells of these animals flared upward at the front to provide clearance for the long, upward stretching neck (in 1574, Abraham Ortelier named the islands for the shell of this particular tortoise subspecies, which resembled a Spanish saddle called a galapago). Meanwhile, on larger islands whose high volcanoes captured moisture from the air, vegetation thrived closer to the ground. Here the tortoises evolved unflared, dome-shaped shells and shorter necks.

  Darwin was obviously taken with the giant tortoises when he made his famous visit in 1835. They were holdovers from the age of dinosaurs. As many as 250,000 of them were distributed among the archipelago’s islands then, though it was just a fraction of the population of earlier centuries. Today, the story is much different. Estimates put the combined number of all the subspecies in the islands at about 15,000. (The only other place on earth with a completely wild population of native giant tortoises—though members of a separate genus—is on the remote atoll of Aldabra in the Indian Ocean, where 152,000 still survive.)

  The exploitation of Galapagos tortoises began soon after the islands were discovered by accident in 1535 by the Bishop of Panama, whose ship drifted off course while en route between Panama and Peru. Such early visitors to the Galapagos recognized the value of the trusting, livestock-sized tortoises—they could live aboard ships for months with no food or water, an ideal way to store meat for ocean voyages centuries before refrigeration. Over the ensuing centuries, tens of thousands of the docile creatures were loaded onto ships by visiting whalers, fishers, and buccaneers. Although there was no room on the Beagle to take on any adult tortoises for meat, we know from his writings that Darwin did enjoy tortoise meat while he visited the islands.

  The tortoises faced more than hungry sailors, however. In the early 1800s, the first permanent settlers of the islands brought dogs, pigs, goats, and cats. By either destroying habitat or preying on the eggs and young, these dom
estic animals played their part in decimating tortoises’ numbers. Moreover, the lumbering reptiles were hunted by settlers for the valuable oil that was produced by rendering their fat.

  Today, the 11 subspecies of Galapagos giant tortoises are found on six islands (two or three other subspecies are thought to have already gone extinct). The largest population is the Alcedo Volcano subspecies on Isabela Island, with an estimated 5,000 individuals. The rarest is Geochelone nigra abingdoni, a saddleback tortoise that originally lived on the small island of Pinta in the northern part of the archipelago. Tortoises are no longer found on Pinta, however. The plants that provided their sustenance had been munched into oblivion by introduced feral goats. But for one individual, affectionately known as Lonesome George, the Pinta Island giant tortoise would be little more than a memory.

  This solitary animal was discovered in 1971 by American biologist Joseph Vagvolgi and was soon moved to the Charles Darwin Research Station on Santa Cruz Island. Lonesome George has been the poster boy for the entire endangered Galapagos ecosystem ever since. As Galapagos tortoises go, he is mid-sized at 90 kilograms and middle-aged at about 90 years old—they are thought to live for 150 years or longer.

  The plight of the Pinta Island giant tortoise is as dire as it gets for a species. Although George is apparently completely alone, there is still a flicker of hope that his species might be saved. He’s kept in a pen with two females from neighbouring Isabela. Although the females are of a different subspecies from George, hopes were that he would breed with one of them and pass his Pinta Island tortoise genes to a new generation. There was a problem with this plan. George hadn’t shown even a glimmer of interest in the fairer sex in decades. That is until 2008, when his libido finally clicked into gear.