Still Watching, from the Edge of Extinction

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Still Watching, from the Edge of Extinction Beverly Peterson Stearns and Stephen C. Stearns

Today, human behavior drives many extinctions and preserves some species. To help understand such behavior, we published a book in 1999 that viewed selected endangered species through the eyes of those who have watched them decline and, in some cases, vanish from the wild. Here we revisit those stories to document what has happened in the interim 10 years, a period that is very short in evolutionary time but that has proven decisive for some endangered species. One species is now extinct in the wild; others have been devastated or scattered; several are on “life support.” Some things have not changed: Too many people consume too much, and disagreements among conservationists still impede progress. Some issues have become more prominent, such as emerging diseases and global economic crises. Although there have been some striking successes, it is very clear that more species now depend on human support for their survival than may be sustainable. Keywords: extinction, endangered species, conservation policy, chimpanzees, haplochromines

T

en years after we documented endangered species

through the eyes of those who monitor them (Stearns and Stearns 1999), we’ve revisited the stories, taking stock of what has happened to both the endangered species and the people who’ve watched their numbers decline. In Watching, from the Edge of Extinction, we selected a range of endangered species from a variety of geographical areas, using the primary requisite that a species had been followed by individuals both well informed on the science of extinction and thoughtful about its meaning. We probed those individuals, asking not only why the species was endangered but also what difference it would make if it became extinct in the wild. Their answers, presented in the book, provided insights from those who had linked their lives to disappearing parts of nature, and offered a nuanced overview of the diverse emotional responses humans have to extinctions, both locally and globally. Our recent update shows that one species has since disappeared from the wild; others have been further devastated, scattered over vast distances or reduced to hiding in caves; and still others are on “life support,” appearing to flourish but supported by budgets that are especially vulnerable in tough economic times. These stories, enlivened by some bright spots and surprises, show that although humans cause extinctions, they also hold the keys to the survival of many species. Humans and other species are increasingly linked in a pas de deux: What affects one, affects the other, individually and collectively. Beginning in 1994, we looked closely at eight endangered species of animals and several endangered species of plants that had been followed by particular individuals for many

years. Our first interview focused on the chimpanzees of Taï National Park in the Ivory Coast. What has happened there confirms that the larger mammals will probably go first, and their absence will certainly be the most noticed. Pan troglodytes Chimpanzee populations have decreased by more than 90 percent in the Ivory Coast in the past 18 years, and the rate of loss appears to have quickened during the last decade. In 1994 and 1997, we interviewed Christophe and Hedwige Boesch, whose work for 30 years in Taï National Park has provided many insights into the evolution, ecology, and behavior of chimpanzees. By 1997, workers from the Boesch encampment had habituated two groups of chimpanzees, and habituation of a third was under way. There were about 100 animals in the three groups, 30 of which were in the Boesch’s original study group in 1977. By late 2008, only one animal from that original group was still alive (a 33year-old female), in a group of 18 with only one adult male. Four groups are now habituated, and there are still about 100 chimps being studied in Taï. The difference is that there are now only 1000 chimpanzees in all of the Ivory Coast, and half of them live in Taï National Park (Campbell et al. 2008), which has the most stable population in the country. Drought throughout West Africa and several wars have contributed to heavy human migration into the country, resulting in a 50 percent increase in the size of a human population that destroys habitat and eats chimpanzees as bush meat. “The forest outside the park has totally disappeared,” observes Christophe Boesch (Christophe Boesch, MaxPlanck Institute for Evolutionary Anthropology, Leipzig,

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A male chimpanzee, Pan troglodytes, studied by Christophe and Hedwige Boesch in Taï National Park, Ivory Coast, 1989. This chimpanzee and all but one of the 30 others in his group have since disappeared. Chimpanzees have decreased by more than 90 percent in the Ivory Coast in the past 18 years. Photograph: Stephen C. Stearns.

Skull of an ,Alala, Corvus hawaiiensis, in the Smithsonian Museum of Natural History, Washington, DC. The ,Alala became extinct in the wild in 2002; about 50 remain in captivity in Hawaii. Photograph: Beverly Peterson Stearns.

Germany, personal communication, 15 October 2008). It is hard to know, he adds, whether the population decline in Taï is natural, or is an “edge effect” on a forest island within a huge cocoa-coffee field. Disease, Boesch says, is the main threat that he had underestimated—and its transmission runs both ways. Outbreaks of Ebola in the 1990s infected both chimpanzees and a researcher. More recently, Boesch and his group at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, found anthrax in the chimpanzees (Leendertz et al. 2004), and confirmed that several Taï chimpanzees died from common respiratory viruses carried by humans (Köndgen et al. 2008). “On the one side, we introduce disease to the animals and kill them, but on the other side we indirectly protect them through our presence by decreasing poaching pressure, which is much higher than the risk of disease transmission,” he notes. Boesch also says that poachers or locals collecting fruit in the park may have introduced diseases. Researchers at Taï now take extensive precautions: They try to keep at least 7 meters away from the animals, and they wear masks, disinfect their boots, change clothing, and wash their hands before entering the forest. He suggests that because of disease transmission, ecotourism also presents a health threat that organizers should do everything possible to limit.

marked the end of a long struggle between Cynthia Salley, the owner of McCandless Ranch, where the last crows lived, and state and federal biologists. Each side claimed to be working to protect the ’Alala, but they often seemed to be working against each other. It had also been a struggle among biologists, some of them local and some outside experts called in for advice. Since the 1970s, state and federal biologists had invested significantly in a captive breeding program for the ’Alala, but captive populations repeatedly died, and eggs put into incubators almost never hatched. Salley spent much of her childhood on the ranch, which had belonged to her grandfather, and she knew the ’Alala well. The birds’ primary enemies were feral cats, rats, and mongooses that ate their eggs; the Hawaiian hawk (also an endangered species); avian malaria; and avian pox. After watching the failed efforts of state and federal wildlife workers to study the birds and set up a captive breeding program, she shut the gate of her ranch and told the biologists to go study the approximately 90 crows living on other parts of the island. Ten years later, in 1988, the only ,Alala left in the wild were on her ranch; the National Audubon Society and the US Fish and Wildlife Service brought suit against Salley and the ranch for violating the Endangered Species Act by denying federal biologists entry. Eventually, after experts from the National Academy of Sciences examined the situation, Salley reluctantly agreed to follow their recovery plan. Despite that plan, the number of crows declined, and birds raised in captivity died shortly after they were released into the wild. “Deep inside, I knew that the interference that was inherent in the recovery plan would cause the ’Alala to die,” she says. “After all, that was basically the reason I fought so hard to prevent it from happening” (Cynthia Salley, McCandless

Corvus hawaiiensis In 1999, after documenting the collapse of the last population of the endemic Hawaiian crow (’Alala in Hawaiian), we stood at dawn in a native forest on the island of Hawaii and saw the last two crows in the wild in the top of a huge koa tree, calling to captive juveniles in an aviary below. By 2002, those two crows had disappeared, and the ’Alala was officially listed as extinct in the wild. Its extinction 142 BioScience • February 2010 / Vol. 60 No. 2


Forum Ranch, Honaunau, Hawaii, personal communication, 18 September 2008). Salley has since retired. Her son-in-law, Keith Unger, is now ranch manager and a member of the recovery team that is making plans to release the 50 Hawaiian crows currently in captivity, which he says may happen in 2011. “If there is a recovery at all, it will be very slow and painful,” he predicts. “I believe, in essence, the ’Alala, as we know them, are extinct” (Keith Unger, McCandless Ranch, Honaunau, Hawaii, personal communication, 16 September 2008). Maculinea arion In June and July of 2006, nearly 10,000 magnificent large blue butterflies emerged to fly into the skies above Great Britain; the next year, at the single site open to the public, about 350 large blues emerged. These figures are notable because Maculinea arion, which had declined in Britain ever since its discovery in 1795, went extinct there in 1979 despite great efforts of scientists and the butterfly’s admiring public, neither of which understood what it needed to survive until it was too late. The large blue butterfly was reintroduced successfully to the wild in 1983, after researchers had determined its life history and ecology, and it has continued its comeback on extremely well-managed and monitored sites (Thomas et al. 2009). The reintroduction of this spectacular and rare butterfly is a tribute to persistence, hard work, scientific research, and the British public’s desire to preserve a species of great beauty. Jeremy Thomas was brought in to work on the large blue butterfly in 1972, when the species was down to just two colonies, one with only 20 individuals. It had already disappeared from large parts of the Palearctic. Although conservationists were familiar with the remarkable life history of M. arion, including the fact that ants raise its larvae, which hatch from eggs laid on wild thyme, no one realized that those particular ants (Myrmica sabuleti) needed warm areas for their subterranean nests. In an effort to protect the ants’ nests, conservationists had fenced them off from wild herbivores and domestic sheep, but as a result, vegetation over them grew deep, shading, and therefore cooling, the nests. By the time Thomas discovered that the ants underground needed warmth to live and care for the butterfly larvae, it was too late: The underground larvae had died in the nests, and the remaining large blues, then in captivity, left no progeny. Thomas reintroduced the large blue in the summer of 1983, using 93 caterpillars from the Swedish island of Öland. He released them onto wild thyme growing on warm ground near the nests of M. sabuleti in Devon. By 1999, there were several thousand butterflies on the carefully monitored sites, and butterfly numbers have continued to increase under vigilantly controlled conditions. Nothing about this is natural, Thomas stressed: The reserves are all artificially groomed (Stearns and Stearns 1999). Thomas, now a professor of ecology at Oxford University, puts the success of the large blue into context by comparing www.biosciencemag.org

it to the rest of Great Britain’s butterflies. The majority (71 percent in 2004) of butterfly species in Great Britain has declined in the past 20 years, along with 54 percent of British birds (Thomas et al. 2004). Eurycea sosorum The updated story of the Barton Springs salamander of Austin, Texas, is probably the most encouraging of the group of species we profiled, but it too exemplifies a species that depends on human support that is, in the long term, uncertain. With monthly census counts soaring from about 9 salamanders before 2003 to 1000 salamanders now living in the springs that contribute to the city’s popular swimming hole, the species appears to be recovering despite massive development on the aquifer. Four biologists have been hired by the city’s Salamander Conservation Program to keep the salamander alive. They believe the population increase has come through reproduction and recruitment, not migration from another site. Like the large blue butterfly, the Barton Springs salamander has support from an admiring public, engaged scientists, and active conservationists. Unlike the large blue, it is not fenced off from the public—there has never been evidence that swimmers disturb it. The Barton Springs salamander was legally protected by a city ordinance passed during a legendary all-night city council meeting in 1990, during which the public loudly voiced their support for the springs. After a string of delays, the salamander was listed as endangered under both state and federal regulations. Pale purple and barely 3 inches long, the salamander lives underground in the rock cobble of the four outlets collectively known as Barton Springs, rarely seen by any of the thousands who swim there every year. David Hillis, one of three scientists who wrote a paper in 1993 describing the species, says that although the situation is far better than it was 10 years ago for the salamanders, it will take sustained, consistent effort to ensure the species’ long-term survival. He remains especially concerned about siltation and runoff from streets and parking lots in the recharge and contributing zones and growing demands for water that threaten the springs during droughts. “The city built a dedicated building for the captive breeding colony, and the biologists have now collected more information on the breeding biology of Barton Springs salamander than exists for almost any other species of salamander on Earth,” he says. “The habitat restoration has resulted in a significant increase in the population of salamanders at the springs” (David M. Hillis, University of Texas, Austin, Texas, personal communication, 28 August 2008). In 2001, Hillis and three other scientists, including one of the city’s salamander biologists, Dee Ann Chamberlain, described a second species in Barton Springs, the Austin blind salamander (Eurycea waterlooensis). “Yet another new species of salamander, at one of the most-studied spots on the planet!” Hillis exclaimed. Laurie Dries, the city biologist in charge of maintaining the wild populations of the Barton Springs and the Austin February 2010 / Vol. 60 No. 2 • BioScience 143

Forum blind salamanders, calls the habitat reconstruction of Eliza Spring, one of the four outlets, a “rocketing success.” However, she tempers her optimism with caution: “We must... restore the natural processes that make an environment resilient because that resilience will buffer Barton Springs from the negative effects of increasing human activity in the upstream watershed” (Laurie A. Dries, Watershed Protection and Development Review Department, Austin, Texas, personal communication, 12 November 2008). Mark Kirkpatrick, a University of Texas biologist who, with Barbara Mahler, a hydrogeologist, filed the petition to put the Barton Springs salamander on the Endangered Species List, describes the pace of development in the watershed area as “horrifying.” He worries that the political climate is changing, and that environmental issues and the springs have a lower profile in Austin than they did 10 years ago: “There are many reasons, for example the large influx of new residents who don’t know, and may not care, about what makes Austin special” (Mark Kirkpatrick, University of Texas, Austin, Texas, personal communication, 8 September 2008). The Barton Springs salamander remains vulnerable. Achatinella We interviewed Michael Hadfield, a marine biologist, in 1996 about his work on the nine surviving species of endemic Hawaiian land snails in the genus Achatinella. All continue to be listed as endangered: Two live only in a lab on the University of Hawaii campus in Honolulu, and only one of those, Achatinella lila, grows well. All of the land snails grow slowly. In remote areas of the wild, some species are hanging on to survival by a thread. These are the remnants of the 41 species of Achatinella collected and recorded in 1912–1914 by 19th-century naturalists who collected them by the thousands—some to extinction. Since then, habitat destruction and introduced rats and snails have further devastated the populations. Hadfield inherited the land snail project more than 30 years ago after a hiking companion who had been studying them dropped out of academia and brought him a large box of data. He has written papers, recruited students, and maintained a captive breeding facility so that he could reintroduce the snails to the wild, juggling marine and snail research and spending considerable time writing applications to fund the snail project, which never received more than a one-year grant. In 2008, he began to receive generous funding from the US Army, which owns land that is habitat for the snails. He is preparing to reintroduce about 300 A. lila to field sites as soon as genetic data have been analyzed to determine appropriate locations. Hadfield, 72, has recently turned over the land snail propagation lab to Brenden Holland, a former postdoctoral researcher who is a conservation geneticist. Four students who have worked in Hadfield’s lab have gone on to graduate school in conservation biology, and two of his graduate students are currently working on land snails. He will leave a conservation legacy—but he may be leaving it sooner than expected. In September 2008, the University of 144 BioScience • February 2010 / Vol. 60 No. 2

Hawaii announced plans to close the Kewalo Marine Laboratory, where Hadfield had been director and maintains an office. The announcement of the closure of the waterfront lab was met with protests from marine biologists, but the university administration declared it could not afford to keep it open. Hadfield hoped to work another four or five years, but now says, “The day we get turned out of here, I’ll retire” (Michael G. Hadfield, University of Hawaii, Honolulu, Hawaii, personal communication, 28 May 2009). Haplochromis When we first interviewed scientists about the introduction of the nonnative Nile perch (Lates niloticus) to Lake Victoria, they estimated the introduction had caused the extinction of up to 200 species of the endemic haplochromine cichlids in the lake. They saw the loss of the great species flock as a tragedy; one even called it a “holocaust.” Now many haplochromines can again be found in the lake, and a few species that had been thought to be extinct may have persisted in satellite lakes. However, since no detailed taxonomic comparisons have been made between the species in the satellite lakes and those that used to live in the main lake, what has transpired remains unclear. Most scientists still believe that Lake Victoria has suffered a major extinction event. The question now is whether it was the Nile perch, the eutrophication of the lake, or both, that caused so many haplochromine species to disappear. “There is no doubt about the recovery of some of the sub-littoral haplochromines,” says Frans Witte, at Leiden University in the Netherlands, whom we first interviewed in 1995 (Frans Witte, Leiden University, Leiden, the Netherlands, personal communication, 19 October 2008). In the fall of 2008, he returned from Lake Victoria, where he had evaluated recent changes. The population density of haplochromines in the sublittoral waters of the Mwanza Gulf has recovered to between 50 and 80 percent of the original numbers, he says, but the number of species remains at 25 to 30 percent of the original diversity. He also observed new fish he identified as hybrids, something he and others attribute in part to the effects of water turbidity on mating behavior (e.g., van der Sluijs et al. 2008). Catches now consist of the former zooplanktivores and detritivores; Witte wonders why

Haplochromis pyrrhocephalus, a zooplanktivore once common in Lake Victoria that virtually disappeared after the Nile perch upsurge in the lake. Now it is again one of the most common species; its morphology has changed dramatically. Photograph: Jan H. Wanink. www.biosciencemag.org

Forum there seem to be more hybrids among the detritivores. One tentative explanation, he suggests, is that these detritivores live, and probably breed, in deeper and murkier water than zooplanktivores. Witte says it is still unclear how eutrophication and the Nile perch may have interacted to cause the demise of haplochromines. He believes that although some species can tolerate and adapt to eutrophic water conditions, the Nile perch negatively affects nearly all species. Nile perch, which accounted for 70 percent of the catch from the lake just after the peak in 1985–1987 (Goudswaard et al. 2008), made up only 40 percent by 2000 and had dropped to 26 percent of the catch by 2006. Whereas surveys suggest that fish biomass in the lake remained more or less constant, every haplochromine species that Witte has looked at in detail has changed ecologically or morphologically. There are indications that changes in the quality and quantity of light, oxygen, and food have had major effects on the fish. Eutrophication and other environmental changes should be the focus of further research on the consequences of the Nile perch introduction, he says. The flourishing fish production in Lake Victoria in the aftermath of the Nile perch boom surprised observers who feared that the Nile perch would eat the haplochromines and then crash for lack of food. Recent production of the filleting factories, which buy Nile perch for export, is reported to be several hundred tons per day. Although Nile perch were introduced to enhance fisheries on the lake and to feed the local people, the benefit has been jobs, rather than protein, for locals. At the moment, the Nile perch appears to be in decline, and another species, Rastrineobola argentea (Dagaa or Mukune), dominates the lake. It and Nile tilapia are sold in the local markets. Lycaon pictus and Monachus monachus Both the African wild dogs in the Serengeti and the Mediterranean monk seals are endangered and elusive. African wild dogs are nomadic, whereas Mediterranean monk seals hide in caves they enter by diving through underwater entrances. The stories of these animals and the people who were studying them were filled with politics; conflicts; competition for funding; and corruption in government, research, and conservation groups. African wild dogs have disappeared from many of the 39 countries where they once roamed. When they disappeared from Serengeti National Park in Tanzania in 1991, Roger Burrows, who had volunteered to work in the park, developed a controversial hypothesis about a rabies vaccination program that required the wild dogs to be shot with darts and then be vaccinated and radio-collared. He believed the handling and vaccination might have contributed to the dogs’ deaths. Burrows put his hypothesis in writing to the head of the Serengeti Wildlife Research Institute, tracing how entire packs had died out after being handled—and his permission to work in the park was then revoked while he was away. Two hyena researchers working in the park defended him, saying he should be able to put forth a working hypothesis about an www.biosciencemag.org

endangered species. Other Serengeti researchers disagreed with Burrows; some of their research depended on handling the dogs. The conflict became complex, with charges and counter-charges among researchers, park administrators, and scientists working in other geographical areas. In 2003, the wild dogs wandered back into the Serengeti from the Maasai Steppe; three years later, there were reports that three packs totaling about 30 dogs had been seen in the park. Burrows holds to his original hypothesis about the effect of vaccinations and handling, and is still concerned that, as the dogs return, vaccination programs may be resumed; a campaign to vaccinate domestic dogs against rabies in Maasai Mara has already begun. A story of similar friction and complexity, with intrigue and allegations of corruption, emerged from the account of the Mediterranean monk seal, a critically endangered species. We had interviewed three people in Greece, all of whom agreed that the monk seal was dying out—a victim of a tourist industry that constructed beachfront hotels, fishermen who shot or dynamited them because they destroyed nets, and pollution of the seas. We spoke with several people, but used only one interview in our book, with Aliki Panou, a Greek researcher who has studied the monk seal for almost 30 years. One of the other people we spoke to sent us an express letter shortly before the book went to press, saying if we used his name or any of what he had told us, he would no longer be able to live in Greece. The motives of a third researcher were questioned by conservationists in Greece, and we dropped the two interviews from our book. There was enough competition, corruption, and conflict to fuel a Greek tragedy. According to reports from a 2006 conference in Turkey and the International Union for Conservation of Nature (IUCN) Red List for 2008, only 350 to 450 monk seals remain in the waters of the Mediterranean, mostly near Greece and Turkey. These are roughly the same numbers as a decade ago. Human-related activities—killing the seals by shotgun, dynamite, or entanglement in fishing nets—continue to be the main causes of death. Panou remains active in conservation projects in Greece, including efforts to set up a marine reserve for the seals and, as before, struggles to fund her work. Her conclusion: “If the seals are left alone, they’ll survive” (Aliki Panou, Archipelagos, Lourdata, Kefalonia, Greece, personal communication, 22 November 2008). That appears to be a big “if.” Mauritius: Island of the living dead? We interviewed Wendy Strahm in 1996 when she was plants officer for the Species Survival Commission of the IUCN; she left that position in 2006. She is now a freelance environmental consultant and is working with the United Nations Compensation Commission on ecological restoration of areas damaged in the first Gulf War. When we first interviewed her, we talked primarily about the 11 years (1981–1993) she had spent on Mauritius working with many endangered plants and eight February 2010 / Vol. 60 No. 2 • BioScience 145

Forum threatened species of endemic birds. She was especially concerned about the plant species that had dwindled to one or two individuals. She called at least 10 species of plants on Mauritius and Rodrigues “the living dead,” because there was only one individual of each remaining and chances of survival appeared slim. For example, several fences had been erected around the sole surviving plant on Rodrigues, locally called the “Café Marron” (Ramosmania rodriguesii), which was previously believed to be extinct. In 1982, Strahm sent two small cuttings of this plant to the Royal Botanical Gardens, Kew. One cutting grew well but produced flowers with a deformed style, and hence did not set seed. In 2003, 20 years later and with help from a new procedure, the Ramosmania at Kew finally produced its first fruits. Surprisingly, the plant in the wild on Mauritius also set seeds the same year, with no outside intervention. There were 20 seedlings being grown at Kew in 2006, but the last Café Marron on Rodrigues had not yet produced any seedlings. In time, that may still happen—but time is in short supply for many endangered species. Conclusion Five messages highlight our update: First, some species are disappearing faster than even those who have been watching closely had expected. Second, other species that appear to be recovering are, in fact, on life support, persisting because of stubborn human advocates, sometimes in artificial environments. This raises a question that has become increasingly pertinent: When these advocates are gone, will others take their places? Third, conflicts among conservationists sometimes become part of the problem. Fourth, some species have persisted despite neglect and assault, reminding us that nature can be impressively resilient. Fifth, a decade has revealed new threats with the potential to cause extinction quickly. The final blow may come not from poachers or habitat destruction but from emergence of disease or a global economic crisis that cuts funds for study, protection, and conservation. The fossil record shows four or five mass extinctions; evidence confirms that we are in another. The difference now is this: Humans have become both the major cause of extinctions (Pimm et al. 2006, Jackson 2009) and the key to survival for many endangered species. The Hawaiian crow disappeared from the wild even as biologists and a stalwart rancher argued about how to save it; humans did better when they had a second chance to save the large blue butterfly in Britain. Chimpanzees in the Ivory Coast are being crowded out by expanding populations and are stricken with

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disease in areas where poor people struggle for farmland and food. The large blue butterfly in Britain and the Barton Springs salamander in Texas are protected by scientists with the means to support them and an active public aware of conservation, but onlookers wonder whether this is sustainable. Wild dogs, monk seals, and land snails may have already found that the best strategy is keeping a low profile in remote areas, away from squabbles among conservationists and independent of researchers. Finally, the resilience of the haplochromines in Lake Victoria and the endangered plants on Mauritius underscores that although some outcomes are unpredictable, not all are discouraging. Acknowledgments We would like to acknowledge all those we interviewed, thank them for their support, and honor the many years of hard work they have given to protect endangered species. References cited Campbell G, Kühl H, Kouamé PN, Boesch C. 2008. Alarming decline of West African chimpanzees in Côte d’Ivoire. Current Biology 18: R903–R904. Goudswaard KPC, Witte F, Katunzi EFB. 2008. The invasion of an introduced predator, Nile perch (Lates niloticus L.) in Lake Victoria (East Africa): Chronology and causes. Environmental Biology of Fish 81: 127–139. Jackson JBC. 2009. Ecological extinction and evolution in the brave new ocean. Proceedings of the National Academy of Sciences 105: 11458– 11465. Köndgen S, et al. 2008. Pandemic human viruses cause decline of endangered great apes. Current Biology 18: 260–264. Leendertz FH, et al. 2004. Anthrax kills wild chimpanzees in a tropical rainforest. Nature 430: 451–452. Pimm S, Raven P, Peterson A, Sekercioglu CH, Ehrlich PR. 2006. Human impacts on the rates of recent, present, and future bird extinctions. Proceedings of the National Academy of Sciences 103: 10941–10946. Stearns BP, Stearns SC. 1999. Britain’s large blue: A star is reborn. Pages 81–95 in Stearns BP, Stearns SC. Watching, from the Edge of Extinction. Yale University Press. Thomas JA, Telfer MG, Roy DB, Preston CD, Greenwood JJD, Asher J, Fox R, Clarke RT, Lawton JH. 2004. Comparative losses of British butterflies, birds, and plants and the global extinction crisis. Science 303: 1879–1881. Thomas JA, Simcox DJ, Clarke RT. 2009. Successful conservation of a threatened Maculinea butterfly. Science 325: 80–83. van der Sluijs I, Van Dooren TJM, Hofker KD, van Alphen JJM, Stelkens RB, Seehausen O. 2008. Female mating preference functions predict sexual selection against hybrids between sibling species of cichlid fish. Philosophical Transactions of the Royal Society B 363: 2871–2877. Beverly Peterson Stearns ([email protected]) is a freelance writer. Stephen C. Stearns ([email protected]) is with the Department of Ecology and Evolutionary Biology at Yale University in New Haven, Connecticut.
