Encouraging news from 2009 Floreana Mockingbird survey

By Paquita Hoeck, Zoological Museum, University of Zürich

The Floreana Mockingbird is one of the rarest birds in the world and occurs only on two tiny islets off the coast of Floreana Island: Gardner-por-Floreana (81 ha) and Champion (9.5 ha) islands, in the Galápagos. Although the species was recorded on the island of Floreana by Charles Darwin in 1835, the last specimen collected on Floreana itself was in 1852 and the last reported sighting here was in 1868. The mockingbird was probably extinct on Floreana island by 1888, when it was searched for and not found, and remains only on the two islets. Extinction from Floreana has been attributed to an island-wide fire in 1819, human hunting, predation by dogs or cats, disappearance of the prickly pear cactus Opuntia megasperma, a favoured place to nest and a source of food, caused by goats, or more likely, predation at the nest by introduced Black Rats. Population estimates from a 2007 survey were: 38 birds on Champion and 98 on Gardner-por-Floreana.

Three years ago, we started ringing the mockingbirds on Champion and Gardner allowing us to get a total count of the individuals on Champion and a much better idea of the population on Gardner using mark-recapture (ringing and resighting) methods. We carried out a new census in February this year and counted a total of 47 mockingbirds on Champion, indicating that this population is still at a high when compared to previous years (~20 individuals). On Gardner, which is harder to access, we were able to cover a much larger part of the island for the first time and, hence, get a more accurate estimate of the population size, calculating between 400 and 500 birds. These estimates show a much bigger population than previously thought on this island and coincide with the large genetic diversity detected. The current high number found on Champion is due to beneficial environmental conditions in the past two years.

The University of Zurich is working with Durrell, Charles Darwin Foundation and Galápagos National Park to restore Floreana to its former state and return the Floreana Mockingbird to the main island. This unique bird was the inspiration behind Charles Darwin’s development of the theory of natural selection and to return it the island where Darwin saw it will be a remarkable achievement. The discovery of more birds on Gardner than previously known is extremely encouraging as this will enhance future plans to move some back to Floreana.