Barbados Leaf-toed gecko (Phyllodactylus pulcher)

Mohamed bin Zayed Species project number 13257761

Background

Island populations of terrestrial reptiles are often vulnerable to human-mediated changes to their environment, such as habitat loss, and introduced invasive species. In the islands of the Lesser Antilles, West Indies, about half of all native reptile species have been affected negatively by human activities, such that many are in decline and others in imminent danger of extinction.  One species that was in urgent need of conservation attention is Phyllodactylus pulcher (Gray 1828), known as the Barbados Leaf-Toed gecko. Endemic to the 430 km2 island of Barbados, P. pulcher is the only species of the genus described from the Lesser Antilles. However, its relative scarcity meant that next to nothing was known about its natural history.  Not seen for 30 years, a small population of P. pulcher was reported on Culpepper Island, a tiny (0.15ha) islet off the east coast of Barbados in October 2011 by a local naturalist.  Having confirmed that P. pulcher was still present on Barbados, it became important to gain information on the distribution of the species and its ecology in order to evaluate its status and direct conservation efforts.

Growing evidence suggests that the widely introduced House gecko (Hemidactylus mabouia) may negatively impact native gecko species in the Caribbean region through competitive interactions. In most cases, displacement of the native gecko species has been incomplete, with the invasive only achieving dominance under certain conditions, e.g. when food resources are clumped, habitat is modified or when co-existence is possible due to subtle morphological differences enabling microhabitat niche separation. The exact nature of the interaction between the two ecologically similar species on Barbados is unknown, and therefore a major goal of the study has been to quantify the degree of niche overlap and the competitive interactions between the species. 

The study

A visual survey of sites for P. pulcher and H. mabouia along the coasts of the south, east, and north of Barbados is underway and animals are being sexed, weighed, measured and whether the tail has regenerated (caused either by predation or by competitive interactions) is being noted. Any tails that are dropped will be collected for population genetic analysis.  To establish whether P. pulcher locations are restricted to certain habitats, ecological data will be compared between confirmed locations and random location points (mimicking sightings) within each survey area where no P. pulcher is found.   The investigation of microhabitat use involves collecting field data on available diurnal retreat site characteristics such as crevice orientation and size, as well as variables of temperature, humidity, perch type, vegetation cover and distance from refuge. Faecal samples are also being analysed to identify whether there are dietary differences between the two species. Finally, using controlled choice experiments with captive animals, the project will identify specific retreat site selection preferences for each species with a view to the possibility of enhancing refugia availability in the wild.  

Anticipated impacts of the research

• Raised awareness for one of the country’s last surviving endemic vertebrates, and promotion of the species as a flagship for conserving other threatened wildlife 

• Data that will allow appropriate classification of the species status in accordance with the IUCN Red List for Threatened Species 

• More effective conservation of P.pulcher by enhancing ecological knowledge of the species and its habitats

• Enhanced local capacity to implement in situ and ex situ methods to monitor and conserve gecko populations through the participation and training of local assistants

• Increased options for management of habitats that exploit behavioural, morphological, and physiological differences between P. pulcher and H. mabouia to favour P. pulcher 

• Quantification of habitat use by P. pulcher leading to more successful captive husbandry of the species should this be necessary in the future, and identification of suitable habitat in the wild for potential reintroductions and augmentation