What's Killing the World's Shorebirds?
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WHAT’S KILLING THE WORLD’S SHOREBIRDS? Researchers brave polar bears, mosquitoes and gull attacks in the Canadian Arctic to investigate an alarming die-off. BY MARGARET MUNRO our gun-toting biologists scramble out the Southern Hemisphere. They make these Although the trend is clear, the underlying of a helicopter on Southampton Island epic round-trip journeys each year, some flying causes are not. That’s because shorebirds travel in northern Canada. Warily scanning farther than the distance to the Moon over the thousands of kilometres a year, and encounter the horizon for polar bears, they set off course of their lifetimes. so many threats along the way that it is hard to Fin hip waders across the tundra that stretches The birds cannot, however, outfly the threats decipher which are the most damaging. Evi- to the ice-choked coast of Hudson Bay. along their path. Shorebird populations have dence suggests that rapidly changing climate BOOTHROYD MALKOLM Helicopter time runs at almost US$2,000 per shrunk, on average, by an estimated 70% across conditions in the Arctic are taking a toll, but hour, and the researchers have just 90 minutes North America since 1973, and the species that that is just one of many offenders. Other cul- on the ground to count shorebirds that have breed in the Arctic are among the hardest hit1. prits include coastal development, hunting in come to breed on the windswept barrens near The crashing numbers, seen in many shorebird the Caribbean and agricultural shifts in North the Arctic Circle. Travel is costly for the birds, populations around the world, have prompted America. The challenge is to identify the most too. Sandpipers, plovers and red knots have wildlife agencies and scientists to warn that, serious problems and then develop plans to flown here from the tropics and far reaches of without action, some species might go extinct. help shorebirds to bounce back. 16 | NATURE | VOL 541 | 5 JANUARY©2 2017017 Mac millan Publishers Li mited, part of Spri nger Nature. All ri ghts reserved. ©2017 Mac millan Publishers Li mited, part of Spri nger Nature. All ri ghts reserved. FEATURE NEWS In chilly summer “It’s inherently massive PRISM survey is nearing completion. peak abundance of insects, so the birds do not conditions, Paul complicated — these It is a short, intense season for both the grow as big. Smith surveys the birds travel the globe, birds and the biologists. The East Bay site, When those undersized knots migrate to Arctic landscape for so it could be any- several hundred kilometres north of the tree their West African wintering grounds, they shorebirds. thing, anywhere, line, comes alive in June with the mating and run into further problems because their short along the way,” says territorial calls of a dozen shorebird species. bills cannot reach deeply buried clams, their ecologist Paul Smith, a research scientist at Among them are the robin-sized red knot, preferred food. “We show the smaller individ- Canada’s National Wildlife Research Centre in which flies up from the tip of South America; uals live shorter lives and have lower survival Ottawa who has come to Southampton Island several plovers and sandpipers; and the ruddy than larger individuals,” van Gils says. to gather clues about the ominous declines. He turnstone (Arenaria interpres) that winters in He says that he had his first close-up look at heads a leading group assessing how shorebirds Latin and South America. the knots’ Arctic breeding grounds last sum- are coping with the powerful forces altering Shorebirds stream north on four main mer, when he joined a US team to study a sub- northern ecosystems. flyways in North America and Eurasia, and species that migrates to Alaska, where chicks’ Researchers say it is now more crucial than many species are in trouble. The State of North growth rates also seem to be slowing as tem- ever to understand how conditions in the Arctic are altering breeding and survival. “This is high urgency,” says ecologist Jan van Gils of the Royal Netherlands Institute for Sea Research in Texel, “FOR KNOTS, THERE IS NO WAY OUT — who is studying the decline of wading birds called red knots (Calidris canutus) that breed in the Russian Arctic. “It’s indeed now or never.” THEY ARE ALREADY AT THE NORTHERN GUNSHOTS AND PANCAKES EDGE OF THE WORLD.” At his base camp on the island, Smith looks as if he could have walked out of a tech lab in Silicon Valley — except for the shotgun America’s Birds 2016 report1, released jointly by peratures climb. The data collected last year slung over his shoulder. He is constantly in wildlife agencies in the United States, Canada are still being analysed, but van Gils suspects motion, up before 7 a.m. and in the helicop- and Mexico, charts the massive drop in shore- another timing mismatch there — chicks miss ter by 9, ready to head north to survey shore- bird populations over the past 40 years. the peak insect emergence. birds. At 6 p.m., he’s in the kitchen cabin, The East Asian–Australasian Flyway, where Conditions are also changing rapidly at humming away as he cooks dinner for the shorelines and wetlands have been hit hard by Smith’s research site in Canada, where sea ice hungry crew returning from their nest hunts. development, has even more threatened spe- last year broke up more than a month ear- He deals with a computer glitch before bed, cies. The spoon-billed sandpiper (Calidris lier3 than it did three decades ago. But when and then scrambles out of his sleeping bag at pygmaea) is so “critically endangered” that it comes to the shorebird population declines 2 a.m. when a curious polar bear wanders into there may be just a few hundred left, accord- at East Bay, says Smith, “there may be more camp. He deters it with several warning shots, ing to the International Union for Conserva- immediate threats than climate change”. which makes for animated conversation over tion of Nature. Snow geese (Chen caerulescens) are high on the pancakes that he whips up later that morn- Red knots are of major concern on several his list of suspects. The goose population has ing. Then, he hikes off to set contaminant col- continents. The subspecies that breeds in exploded in North America, and they have lectors in thigh-deep melt ponds to check for the Canadian Arctic, the rufa red knot, has severely degraded wetlands along the coast of pollution that might be affecting the birds. experienced a 75% decline in numbers since Hudson Bay that serve as key refuelling stops Smith has been coming to this site, known the 1980s, and is now listed as endangered in for millions of migrating shorebirds4. as East Bay, every year since 2000, when he was Canada. “The red knot gives me that uncom- Geese are also showing up in shorebird sent here as a biology student to help build a fortable feeling,” says Rausch, a shorebird breeding territory, where they mow down the camp to study poorly understood shorebirds. biologist with the Canadian Wildlife Service grasses that the shorebirds use to protect their He was soon intrigued by the birds — some no in Yellowknife. She has yet to find a single rufa- nests on the wide-open landscape. Perhaps bigger than a sparrow — that fly across conti- red-knot nest, despite spending four summers even more threatening, says Smith, is that the nents to lay eggs on the wide-open landscape. surveying what has long been considered the geese attract foxes and other predators that eat Sleet is not uncommon in June, cold winds bird’s prime breeding habitat. shorebird eggs and chicks. blow in off Hudson Bay in July and snowdrifts The main problem for the rufa red knots is Southampton Island is an ideal spot for can persist well into August. thought to lie more than 3,000 kilometres to gauging the impact because there are now about Smith now heads studies at the 12-square- the south. During their migration from South 1 million nesting snow geese on the island. A kilometre research plot at East Bay, one of the America, the birds stop to feed on energy- sister research site that Smith runs on nearby longest-running shorebird-research camps rich eggs laid by horseshoe crabs (Limulus Coats Island — less than an hour away by Twin in the Arctic. He is also co-leader of a joint polyphemus) in Delaware Bay (see ‘Tracking Otter aircraft — provides a control because the effort between Canada and the United States trouble in the Arctic’). Research suggests that island does not have a snow-goose colony. called the Arctic Program for Regional and the crabs have been so overharvested that the International Shorebird Monitoring (Arc- red knots have become deprived of much- HIDDEN NESTS tic PRISM). The project, which began in needed fuel. One day in late June, biologist Lisa Kennedy 2002, has dispatched crews to more than In other cases, climate change might be the calls out a warning as she surveys the East Bay 2,000 sites, stretching from Alaska to Baffin prime problem. Van Gils’ team in the Nether- research site. “Careful where you step,” says Island in eastern Canada, to survey the 26 lands has found that red knots that breed in the Kennedy, sticking to the larger rocks for fear shorebird species that breed in the North Russian Arctic produce smaller offspring dur- of crushing the speckled eggs of a plover. A American Arctic. Smith and his Canadian ing summers when the snow melts early2.