“An important step.”
That’s what Charles Darwin Foundation scientist Francesca Cunninghame is calling the results of a dramatic rescue operation to save the Mangrove Finches on Isabela Island, pulling them back from the brink of extinction. Nine weeks later, the foundation and the Galápagos National Park report that 15 finch chicks raised in captivity are back in the wild, doing fine. It’s likely they wouldn’t have made it without human intervention.
Cunninghame, in charge of the rescue, had to crawl as far as 50 feet up into the canopy to scoop up finch nests containing 21 eggs and three hatchlings and lower them to her teammates.
As Galápagos Digital reported in February, the group from the Darwin Research Station, the Galápagos National park and the San Diego Zoo was spurred into action because the Mangrove Finch population had dropped to between 60 and 80 birds.
The finches are endangered because of a parasitic fly, Philornis downsi, brought to the Galápagos by humans half a century ago. The fly lays its eggs in the birds’ nests and when the larvae hatch, they go after the baby finches, sucking their blood and killing them.
The remedy was to place the eggs in a portable incubator and transport them by boat to Santa Cruz Island where the birds could be raised in quarantine, away from the fly larvae, before being released into the wild.
The chicks, all infested with fly larvae, were evacuated via helicopter to Santa Cruz. There, they were swabbed with petroleum jelly. The larvae, deprived of air, crawled to the surface where technicians removed them with surgical forceps. Of the first three finch hatchlings treated this way, two survived.
They and the other chicks that eventually hatched had to be fed by hand as often as 15 times a day at the start.
“It’s incredible,” said Cunninghame, “that in late January we collected the eggs and now we’ve got the 15 chicks raised in captivity free in their natural habitat.”
That may not sound like many, but considering only six finch chicks born in the wild made it to the fledgling stage of life, it’s a 200% increase in the number of young birds.
“We now have a way to significantly increase the number of fledglings produced each year,” Cunninghame said.
The big fear for Cunninghame’s team was whether the birds would make the transition to the wild in good shape. The finches were transported from Santa Cruz to “halfway house” pre-release aviaries on Isabela as the rescuers worked on getting them used to life in the wild.
After spending their first weeks of life in aviaries, would the birds be able to forage for food on their own without depending on human keepers? Team members filled the aviaries with dead logs, leaf litter, tree branches native fruits and black mangrove seeds containing caterpillars to get the finches used to the idea of searching for natural food.
The process of liberation was a gradual one, with rescuers releasing the finches from captivity in stages and leaving the doors to the aviary on Isabela Island open so that the birds could return for food. The birds were fitted with tiny transmitters so that the rescue team could track their movements.
Over time, the scientists said, the birds became more and more independent, flying farther from the aviary, returning for food less frequently and interacting with other finches in the wild.
“Apparently, they were able to recognize their own kind,” Cunninghame said, “This is encouraging.” Now, scientists are waiting to find out how many of the birds will survive their first year of freedom.
The project is funded by Save Our Species, International Community Foundation with a grant from The Leona M. and Harry B Helmsley Charitable Trust, Durrell Wildlife Conservation Trust and Galapagos Conservancy.
After Charles Darwin returned from his 1835 Galápagos expedition, it was the differences in a dozen species of finches he and others collected and classified that helped him formulate his theory of evolution by natural selection. It’s significant that in the years since Darwin’s time, no species of Galápagos finch has gone extinct, emphasizing the importance of saving the Mangrove Finch.
Meanwhile, the question of what to do about the Philornis downsi fly lingers. A few weeks ago, researchers from the University of Utah tested a possible solution: cotton-picking finches.
A team led by Sarah Knutie set up dispensers with cotton containing permethrin, a mild pesticide, on Santa Cruz, where the birds are of a different species than the Mangrove Finches. The birds grabbed the cotton as nesting material, in effect, fumigating their own nests. Writing in the journal Current Biology, Knutie and her colleagues observed that just one gram of treated cotton incorporated into a nest was all it took to kill the flies.
The Galápagos National Park directorate will have to analyze the risks of this method and conduct more studies, but the self-fumigation strategy could help protect the finches in the near term. Still, experts are searching for a long term solution to the fly infestations that plague the finches, perhaps employing wasps that prey on the flies. The challenge in the fragile Galápagos ecosystem is to make sure that there’s no negative impact on insects native to the islands as they try to make life safe once more for the finches that inspired Darwin.
We’ve expanded our original story a bit and cleaned up some of the quotes that were translated from Spanish to English in the first go-round.