National Geographic : 2017 Jun
life in the Balance 69 Insults to the plants and animals of the Galápagos may be coming too fast and from too many angles to give them a chance to adapt. Her cargo: members of one of the world’s rarest bird species. Cunninghame is taking them home. The famed finches of the Galápagos, known as Darwin’s finches—there are 18 recognized species (genetic studies are under way, and new species will likely be identified)—hold a prized, if erroneous, place in the popular imagination as the linchpin of Darwin’s understanding of evolu tion. In truth Darwin didn’t identify the islands where he collected finches and only realized his blunder upon returning home to Shrews bury, England. So mockingbirds added to his later understanding of how one species might replace another through natural selection. One of Darwin’s finches is the mangrove finch, which today lives in just two isolated patches (totaling about 74 acres) of forest here. Invaders already have found them—eggeating rats and Philornis, a relative of the housefly that invades nests and has likely contributed to the local extinction of a warbler finch on Isla Floreana. Philornis larvae in nests increase in years of high rainfall according to one study, which could sug gest more problems to come. Many land birds here are a bit like Goldilocks, preferring neither too little rain nor too much: Another recent study found that heavy rainfall led to decreased surviv al of fledglings. Today fewer than 20 breeding pairs of mangrove finches remain. Carrying her precious load, Cunninghame walks barefoot across the burning sand and into a forest of tall mangroves. The light fades. The air cools. We walk deeper. A small wooden aviary appears. It’s raised above the forest floor and contains three screened chambers joined together that keep out predators. Inside, Cun ninghame and her three assistants set to work laying out breakfast for the birds. They shut the aviary doors. Cunninghame opens the cages and gently removes 15 chicks one by one. Just four to eight weeks old and sooty in color, they seem less birds than puffs of cigar smoke. Within minutes three chicks stand on the rim of their feeding dish, talking with their mouths full. For the next six weeks Cunninghame and others will remain here to release them gradual ly into the wild and conduct other research. Had they not collected and nurtured the season’s first chicks and eggs, the birds all likely would have died, she says. For the past four years, research ers with the Charles Darwin Foundation—in partnership with the Galápagos National Park Directorate and in collaboration with San Diego Zoo Global and Durrell Wildlife Conservation Trust—have worked to boost the population. Cunninghame still worries. “Any change, or increase in sea level, could potentially destroy this forest,” she says. Mangrove finches prefer to nest in black and white mangroves that are buff ered a bit from the open sea. It’s unclear how well they would adapt if those forests vanished. Cunninghame is more than three months preg nant and feeling a bit unwell, so she lies down on the floor of the aviary and watches the fledg lings. She laughs when the birds bicker, and then smiles. Something heavy seems lifted from her. “ They’re back where they should be,” she says. There is a lot more work to do. For a few min utes, though, Cunninghame lies in the dappled light and listens to the little birds. For a moment it’s the sound of victory. j Christopher Solomon is a science writer based in Seattle and a contributing editor at Outside magazine. Thomas P. Peschak photographed the Seychelles for the March 2016 issue of National Geographic.