Demography and conservation of the Floreana racer (Pseudalsophis biserialis biserialis) on Gardner-By-Floreana and Champion Islets, Galápagos Islands, Ecuador : thesis submitted in partial fulfillment of the requirements for the degree of Master of Natural Science
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Date
2017
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Massey University
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Abstract
The Floreana Racer (Pseudalsophis biserialis biserialis) is a mediumsized
colubrid endemic to the islets of Gardner-by-Floreana and Champion off
the coast of Floreana Island, in the South of the Galápagos Archipelago. The
subspecies was historically abundant on Floreana Island, as indicated by subfossil
remains, however is has since been extinct there since the late 1800’s
as a result of the effects of large-scale habitat modification, fires and the
introduction of rats and cats. I conducted the first field study on the population
size, inter-island morphological variability and the diet of the Floreana racer on
the two islets where the species occurs as a first step towards the
translocation of Floreana racers to Floreana Island. Fieldwork took place over
30 days between November 2015 and January 2017. With the assistance of
eight colleagues and volunteers I conducted daylight searches for Floreana
racers yielding a total of 123 individuals, 20 on Champion and 103 on
Gardner-by-Floreana. Of these 119 individuals were marked with unique PITTags.
I also conducted a mark-recapture estimate of population size on both
islets based on 17 recaptures. The resulting estimate of the global population
of the subspecies is approximately 3088 individuals (Champion 209 snakes;
Gardner-by-Floreana: 2879 snakes). I also investigated the diet of Floreana
racers via analysis of faecal samples from 29 individuals. The most common
prey items are lava lizards (Microllophus grayii), followed by the Floreana
gecko (Phyllodactyllus baueri). Lastly I discuss the conservation status of the
subspecies and future areas of research and management to advance the
knowledge, and conservation status of the Floreana Racer.
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Snakes, Floreana racer, Pseudalsophis biserialis biserialis, Galapagos Islands, Ecuador, Research Subject Categories::NATURAL SCIENCES::Biology::Terrestrial, freshwater and marine ecology::Terrestrial ecology