Above: Scientists say no negative effects have been recorded when inserting permethrin at the base of mangrove finch nests. But it has been a very effective method at killing Philornis downsi fly larvae. Photo: Michael Dvorak


CONSERVATIONISTS HAVE COME up with an ingenious pest solution that could save a highly threatened species endemic to the Galapagos Islands.

Classified as Critically Endangered, the mangrove finch (Camarhynchus heliobates) is only found on Isabela Island. Its main threat is from the larvae of an invasive parasitic fly called Philornis downsi, which often causes chick mortality.

For the past four years, Francesca Cunninghame, coordinator of the Mangrove Finch Project and her team at the Charles Darwin Foundation (CDF), have been “headstarting” mangrove finches by taking eggs from the wild, rearing young in captivity and releasing them back into their native habitat.

While there are fewer than 20 breeding pairs left in the Galapagos Islands, the team has released 39 fledglings into the wild and increased the population of juvenile mangrove finches by more than 50 per cent.

Despite this success, they want mangrove finches to incubate and raise their own chicks, without the threat of Philornis downsi.

To enable this, the scientists are injecting a chrysanthemum-based insecticide called permethrin into the base of finch nests to kill the fly larvae and therefore lower the mortality of chicks.

So far this breeding season, seven mangrove finches fledged in the wild from three injected nests that initially had the presence of Philornis downsi.

Ms Cunninghame said: “It’s great to know there’s a method that can protect nestlings from Philornis in the wild. However, mangrove finches and their nesting ecology in the tall mangroves don’t make this easy. We do our best to access the nests and protect the chicks. The finches are at such a critical stage that they really need intensive conservation during the breeding season and we must actively intervene to make sure as many as possible survive to fledge.”

The Mangrove Finch Project is a bi-institutional project carried out by the CDF and the Galapagos National Park Directorate in collaboration with San Diego Zoo Global, Auckland Zoo and Durrell Wildlife Conservation Trust.

For more project information or to donate, visit: www.darwinfoundation.org/en/donate 

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