During Charles Darwin’s journey to the Galápagos in the 1830s, he noted the existence of “a curious group of finches” found only on the islands. The story that those birds inspired the theory of evolution has long been doubted. But the finches still bear Darwin’s name and are prized by biologists as one of the best examples of speciation—the process by which new species arise. 
 
 Now, research suggests that at least some of Darwin’s famous finches might soon be driven to extinction by parasitic flies introduced to them by humans in the 1960s. A paper published this week in the Journal of Applied Ecology blames the parasitic nest fly Philornis downsi for the threat to Geospitza fortis, also known as the medium ground finch. 
 
 While adult P. downsi flies are not themselves parasitic, they lay their eggs in bird nests. The eggs hatch into maggots, which feed on both brooding adult finches and their babies. The adult birds are unaffected, but it’s another story with the tiny nestlings. P. downsi kills huge numbers of baby birds among Darwin’s finches and other land birds. The flies can be found on every island in the Galápagos. 
 
 “This is like a really bad horror flick,” senior author Dale Clayton, an ecologist and parasite specialist at the University of Utah, says with a rueful laugh. “The babies can’t withstand even one night with these parasites.” The susceptibility of the baby finches has something to do with their size—Clayton compares the newly-hatched birds to peanut M&M's—and their immune responses. 
 
 The sight of a parasite-infested G. fortis isn’t just alarming because of the tiny bird’s anemic looks and bulging lesions. It is also a harbinger of the species’ coming extinction. Clayton and his team used five years of field data to predict the species’ long-term viability and found that, in two out of three scenarios, medium ground finches could be gone within the next century. 
 
 The team first manipulated the parasite load in actual nests, studying only the medium ground finches, which are the most abundant and have the most accessible nests. They created a control group of nests that they sprayed with plain water, while a second set of nests was sprayed with permethrin, an insecticide that is also used to kill mosquitoes, lice and ticks. The use of treated and untreated nests allowed the team to determine the direct effects of the flies on the birds. They then used that data in models of good, bad and neutral years for the birds’ reproduction and ultimate survival. 
 
 The team predicts that if the finches were to run into a series of bad reproductive years in which extreme weather cuts off their food supply, they’d go extinct in about 50 years. A model weighted toward neutral years indicates they’d be extinct within about 80 years. Unsurprisingly, a run of good reproductive luck would spell longer survival for the species: about 100 years. Reducing the number of flies could help the birds hold on even longer, or even prevent them from going extinct at all. 
 
 While Clayton’s team focused on medium ground finches, given that there are at least 14 species of Darwin's finches in the Galápagos—and that they are so closely related—the problem likely extends to other species. 
 
 For instance, a cousin of the ground finch, the mangrove finch, has already become one of the rarest birds on Earth due to the flies and other predators. If any species is lost, it will be a disaster not just for biodiversity, but for researchers who see the finches as an example of real-time evolution due to their rapid adaptations. 
 
 Since the Galápagos so far has its entire native population of birds intact, its importance to biologists is unparalleled. But for Clayton, it goes further than that. “If Darwin’s finches go extinct, it will be because people brought this fly to the islands,” he says. “If the fly had gotten to the island more gradually, perhaps, maybe the birds would have had more time to adapt. But at this point, it’s just an arms race.” 
 
 Luckily, there are ways that the finches could beat both P. downsi and time. The team estimates that if nest fly infestations were reduced by just 40 percent, the birds won’t go extinct. Scientists are batting around ideas such as flooding the island with sterile male flies or allowing birds to fumigate their own nests with permethrin. 
 
 And don’t underestimate evolution, either: Clayton says there’s an outside chance the finches could still develop their own defenses against the flies. In the meantime, can humans stave off the finches’ untimely demise? “Maybe not. But we’re hopeful.” ||||| A simple intervention can help Galapagos finches to stave off an insidious parasite. Offered insecticide-soaked cotton, birds from four finch species wove it into their nests and effectively stamped out an invasive nest fly, researchers report today in Current Biology. The fly Philornis downsi represents a serious threat to the iconic birds, whose speciation patterns were key to Charles Darwin's theory of evolution. Its larvae feed on blood from newly-hatched finches and have been known to kill all a year's nestlings at a given field site. 
 
 The larvae were found to be killing off nestlings in Ecuador's Galapagos Islands in the 1990s, spurring conservation ecologists and others to seek a way to eliminate the flies without harming the birds. Now, with funding scarce and the finch population declining, it turns out that the answer might be as simple as giving the birds the means to conduct their own pest extermination. 
 
 The idea of self-fumigation came to study co-author Sarah Knutie in 2010 while she was sitting on a porch at the Charles Darwin Research Station on Santa Cruz island in the Galapagos, where she was conducting research on the fly and its effects. 
 
 “I noticed finches taking laundry line back to their nests,” says Knutie, a conservation ecologist at the University of Utah in Salt Lake City. When Knutie provided a stash of cotton balls, the birds took those, too. A few years later, during a workshop on pest-control ideas, she proposed putting insecticide-soaked cotton balls in dispensers for the birds to take back to their nests. 
 
 “I don’t know that I was taken seriously, but I thought it could be an immediate solution,” she says. 
 
 Nest test 
 
 In January 2013, after raising money for a plane ticket and supplies through crowd-funding website RocketHub, Knutie returned to Santa Cruz Island to test her hypothesis with some colleagues. 
 
 Between January and April, during the finch breeding season, the team distributed 30 cotton dispensers throughout a study site measuring roughly 600 by 80 meters. Half of the dispensers contained cotton treated with dilute permethrin, an insecticide commonly found in head lice shampoo; the rest contained cotton treated with water. 
 
 By the end of the breeding season, the authors had located 26 nests, 22 of which contained cotton. The nests woven with insecticide-treated cotton harbored about half as many flies on average as the nests woven with water-treated cotton. Further inspection revealed that insecticide effectiveness depended on the dose: seven of the eight nests that contained at least one gram of insecticide-treated cotton had no parasites at all. 
 
 In a separate experiment, birds in nests manually sprayed with insecticide had roughly 30% more fledglings than birds in nests sprayed with water. 
 
 Self help 
 
 The research is proof that the method can be effective, says Peter Grant, an evolutionary biologist at Princeton University in New Jersey who with his wife Rosemary spent four decades working with Darwin’s finches. “Now the challenge is to devise a method whereby a large amount of cotton with substantial quantity of insecticide can be delivered reliably to nests,” he says. “This is needed to ensure maximum effectiveness.” 
 
 Working with the Galapagos National Park Service, which monitors the islands' ecology, researchers at the Charles Darwin Research Station are now assessing permethrin risk to the birds and natural areas. Another group at the station has started offering untreated cotton to different finch species on the neighbouring island of Isabela to gauge the birds' interest. 
 
 “Right now,” says Charlotte Causton, a senior researcher at the Charles Darwin Foundation in the Galapagos, “this is the only control method that’s feasible.” 
 
 This article is reproduced with permission from the magazine Nature. The article was first published on May 5, 2014.
– Charles Darwin's finches of the Galapagos Islands—renowned as a poster child for speciation (that's "the process by which new species arise," explains Smithsonian)—may not be able to evolve fast enough to stave off extinction, according to a study published last week in the Journal of Applied Ecology. The medium ground finches of Santa Cruz Island are having their newly hatched babies decimated by Philornis downsi, a parasitic nest fly humans brought to the islands half a century ago. The flies lay their eggs inside the birds' nests, and the hatching maggots feed on the young birds. "This is like a really bad horror flick," study author Dale Clayton says. "The babies can't withstand even one night with these parasites." According to Discovery News, the flies were first spotted in the finches' nests in 1997. Since then, the population has been growing, and none of the Galapagos Islands is free of the flies. Researchers looked at five years of field research on the medium ground finches specifically on Santa Cruz and came up with three scenarios—good, bad, and neutral—based on breeding, weather, and food supplies, Discovery News reports. In both the bad and neutral scenarios, the finches have less than 100 years before they're extinct. According to Smithsonian, the same fate is likely facing some of the other 14 species of Darwin's finches. "If Darwin's finches go extinct, it will be because people brought this fly to the islands," Clayton says. "If the fly had gotten to the island more gradually, perhaps, maybe the birds would have had more time to adapt." Researchers believe a 40% reduction of nest infestations could save the finches and are looking at options to accomplish that, Discovery News reports. (A frog named for Darwin has already gone extinct.)