Animals and plants worldwide are responding to shifts in the environment — and so must the scientists who study them.
Reptile researcher Russell Burke saw 14 years of fieldwork nearly wiped out in a moment, when Hurricane Sandy hit the US east coast in 2012. Since 1998, he had been studying the population dynamics of two native species of turtle — their clutch size, seasonal movements and more — at Jamaica Bay Wildlife Refuge in New York City, near his workplace at Hofstra University in Hempstead.
But in 2012, storm surges breached the wall of a pond that was home to 22 snapping turtles (Chelydra serpentina) in his study, and all were killed when the waves turned the pond from freshwater to salt. The region's diamondback terrapins (Malaclemys terrapin), which prefer brackish waters, fared better there. Burke noted intriguing responses. “They started nesting in places they hadn't before, and stopped in others where they had,” he says. But the breach lost him easy access to the terrapins' nesting area, so his team could examine only a fraction of the nests.
It will be years yet before the wall is repaired, salinity drops and the snapping turtles are reintroduced. It will take longer still for Burke and his team to assess the storm's full impact on both species' populations. It is a blow to his turtle research programme. “We're going to have this big gap,” he says. “Until they fix the breach, we can't figure out what's really going on.”
Shifting weather patterns — milder winters, wetter springs and storms that are more frequent and more severe — are increasingly changing the landscape for scientists who study flora and fauna in the field (see 'In the face of unpredictability'). Glacier lilies in the US midwest are blooming before their hummingbird pollinators arrive1; malnourished Atlantic salmon are entering Scottish waterways later2; birds and plants are moving higher in the Swiss Alps3; and amphibians in drought-stricken California are struggling to stay alive4. All over, environmental changes are forcing plants and animals to modify their survival tactics.
Ecologists, wildlife biologists, behaviouralists and others who do fieldwork must in turn respond and be flexible. They might have to change how they evaluate habitats during field surveys, head into the field earlier or factor more staff and equipment into their budget. If they visit remote regions, they may need to pay more attention to their physical safety as extreme weather events become more violent or frequent, and as changing conditions bring greater threat of wildlife encounters.
For some, those encounters can be dangerous indeed. George Divoky, director of the non-profit scientific organization Friends of Cooper Island, routinely considers personal safety now as he studies black guillemot (Cepphus grylle), an Arctic sea bird that breeds on the island, which is off Alaska's north coast. In 2002, a search-and-rescue squad had to collect him and his team in a helicopter because polar bears moved in to their camp as a result of ice melt. In earlier decades, only solitary bears had been spotted in the distance on the 5-kilometre-long island. That year, more than two dozen went rummaging through the scientists' tents over a four-night period. “I carry a loaded shotgun all the time now when I go to the island,” says Divoky.
As the geographic ranges of studied species shift or become more varied or diffuse, researchers might need more or larger field sites, which requires more travel and hands-on help. Robert Curry, a species-hybridization specialist at Villanova University in Pennsylvania, found this out in 2003. He works on the causes and consequences of interbreeding between two chickadee species with overlapping habitats. When he started his research in 1998, he had a field site in a spot where the ranges intersected, as well as single-species zones to the north and south. But by 2003, he and his team had begun to notice changes in the most northerly area, including the emergence of birdsong associated with the southern chickadee species, which had shifted its range northward to adapt to warmer winters5.
boxed-textAs a result of that migration, Curry had to add a fourth study site 24 kilometres above the most northerly area to single out a pure population. Each spring, he travels from Villanova, 48 kilometres below the southernmost site, to 200 nests across his 4 field sites. If he had time to visit all of them in one trip, he would end up travelling more than 160 kilometres to study adults and nestlings. Curry estimates that the extra site has added 160 hours of fieldwork annually.
Ecologist Chris Thomas at the University of York, UK, had to add staff members after one of the butterfly species that he investigates shifted its location. The silver-spotted skipper (Hesperia comma) — once restricted to south-facing hillsides — had moved by the end of the 1990s to taller, shadier vegetation on hillsides that face east and west, and now even on some that face north6. “There is a lot more land to cover,” he says.
When Thomas launched his programme in 1982, he needed only one lab member to survey the butterfly's habitat. But by 2009, that number had ballooned to 12. And he needs more help yet: he now relies on field-site temperature gauges and on an ecologist colleague to model habitat temperatures in the butterfly's range.
Although his fieldwork and analysis have grown more complex, Thomas says that it's important to have longitudinal data. “The real value is keeping the research going and understanding those long-term changes,” he says.
Some scientists have to shift focus entirely when conditions change. In 1998, Paul Dolman, an applied ecologist at the University of East Anglia in Norwich, UK, began to explore how and why the habitat of woodlarks was changing in the 19,000-hectare Thetford Forest, a plantation in Breckland, UK. The UK Forestry Commission has managed and logged the forest for decades to support Corsican pine (Pinus nigra ssp. laricio), which thrived in the region's warm, dry climate. In 2000, the commission began to discuss designating the forest as a conservation site for woodlark (Lullula arborea), whose numbers had peaked at 456, and the plan was finalized in 2006. Despite special protection, the woodlark population has since declined to less than one-third of that number. The question is: why?
Woodlark, surveys found, prefer short grasses growing in spots where Corsican pine has been felled. But Dolman, who had pored over a century's worth of precipitation and 60 years of temperature records for the district, saw that the climate was becoming milder and wetter. His preliminary findings showed that vegetation in the clearings was growing more quickly, which rendered the areas uninhabitable to woodlark. He set out to clarify whether climate-driven vegetation changes were involved in the decline.
He never got an answer — in 2008, he was forced to change gears. The forest's increasingly wet conditions nurtured the growth of a fungus that began to stunt Corsican pine growth, and the commission began to replace the trees with hemlock, fir and other species. Dolman and his team have since begun to study the woodlarks' habitat preferences among the new trees, and how the forest should be managed to keep the bird population healthy. “Be ready to think on your feet,” he warns.
The cost of environmental changes can also add up. Divoky has had to raise more than US$32,000 to buy extra equipment and supplies as a direct result of the changing environment. Among his purchases are 200 plastic cases for the guillemot, after bears learned in 2009 how to open wooden nest boxes and ate all but one fledgling; an electric fence to deter the bears; a freezer, because the weakened permafrost can no longer support a freezer pit; and rain gear to endure more-violent and frequent rainstorms.
He does not know what he will face this spring during his annual trek to the island. “But,” he says, “I'm prepared to deal with it.”
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