UPDATE ON THE FLOREANA MOCKINGBIRD PROJECT
Luis Ortiz-Catedral, Massey University
From August 2010 to January 2013, I had the opportunity to work at the Charles Darwin Foundation in the Galapagos Islands on a number of projects related to ecological restoration and management of endangered species. The main project I was involved with was the Reintroduction of the Floreana mockingbird (Mimus trifasciatus) to its island of origin: Floreana Island. The species disappeared from Floreana by 1900’s and currently it is restricted to two islets with a combined area of about 100 ha: Champion and Gardner Islets. Invasive species have plated a role in the disappearance of Floreana mockingbirds and five other vertebrates from Floreana. In 2007, a project to reintroduce mockingbirds back onto this island was launched and the preliminary fieldwork begun in 2008.
In May 2011, The Friends of Galapagos New Zealand, kindly donated a CANON lens to the Charles Darwin Foundation to assist on the project mentioned above. On Champion and Gardner Islets, a large number of Floreana mockingbirds have metal and colour rings, which are useful to estimate survival of individuals as well as changes in population sizes at these sites. Unfortunately, the mockingbirds can be very swifty! Which means often the individual ring combinations cannot be determined. High-speed telephoto lenses help in this task as many photographs of ringed mockingbirds can be obtained, creating a permanent record of sightings. Although the actual reintroduction of Floreana mockingbirds is unlikely to happen before 2015, the necessary basic research on the biology of this critically endangered species has continued from September 2010 to January 2013. In particular, emphasis has been placed on estimations of population size, a critical measure in the context of reintroductions.
From May 2011 to January 2013 a total of 21 field trips took place to Champion and Gardner Islets, during these fieldtrips, eleven volunteers including three Ecuadorians and six New Zealanders have been trained in field methods to study Floreana mockingbirds. Combining sightings of mockingbirds in the field during fieldtrips, photographs and records of sightings from June 2010-January 2013, updated estimates of population sizes for both islets have been obtained. On Champion and Gardner, a maximum of 204 ringed Floreana mockingbirds have been confirmed alive by June 2012, while the minimum number of ringed Floreana mockingbirds confirmed alive was 170 in July 2011. On Champion Islet, where the entire population is ringed, a maximum of 70 individuals has been confirmed alive in February 2011 and September 2012 following extensive searches on the tiny islet (9.5 ha). The minimum number mockingbirds confirmed alive at this location was 57 in June 2012. These estimates are based also on 219 capture and re-capture events since June 2010. On Gardner Islet, where the population number is estimated using sightings of ringed vs un-ringed birds, the highest estimate is 694 individuals, based on a total of 124 Floreana mockingbirds confirmed alive by July 2012. Considering the later estimate, a global population of 756 Floreana mockingbirds is likely.
These estimates for Champion and Gardner are indeed good news considering that when I started studying this species the maximum estimate indicated 150 Floreana mockingbirds left in the world! We have improved our ability to estimate actual numbers of mockingbirds on remnant populations. However, there is still plenty of work to be done. A large initiative has been launched to eradicate rats and cats from Floreana Island, in preparation for the reintroduction of Floreana mockingbirds and other species such as the Floreana racer (a kind of snake). As the preparations for a large-scale eradication take place, more information on the biology of Floreana mockingbirds will be accumulated, which will facilitate the capture, transfer and monitoring of the species once Floreana Island is free of rats and cats.
In February 2013 I left the Galapagos Islands to take a position at Massey University in Auckland, were I currently lecture and develop research projects on parakeets in Australia and New Zealand. Starting in December 2013, I will be visiting the Galapagos Islands once or twice a year as a collaborating scientist to advance research on the Floreana mockingbirds in preparation for a reintroduction of the species onto Floreana Island.