PhD project: Population status and conservation of the critically endangered Bermuda rock lizard (Plestiodon longirostris)
A collaboration with Chester Zoo, Bermuda Department of Conservation Services and the University of Manchester.
It is estimated that only 2,500 Bermuda rock lizards (skinks) currently exist in the wild and are now classed as critically endangered as a result. Since 1965, their population has been decreasing and has become extremely fragmented across Bermuda and its offshore islands. Their population decline is more evident on Bermuda ever since man's colonisation, causing habitat loss and destruction, and introducing invasive species.
A mark and recapture survey and pitfall trap system will be employed across the skink’s range on Bermuda. This will involve surveying all mainland and offshore island sub-populations including those at Spittal Pond, Daniel’s Head, Palm Island, Nonsuch Island, Castle Island and Southampton Island.
The main aims of the research will be to:
- Re-estimate the size of the total skink population and compare this with the last survey in 2004 to determine whether there have been any significant changes in the current health of the populations.
- Investigate the current distribution patterns by undertaking a mark and recapture survey on Bermuda and its offshore islands. This will help to gain an insight into the overall demographics including sex ratio, longevity and percentage of juveniles, sub-adults and adults in the population and determine trends in population dynamics.
- Compare habitat choices between sub-populations of skinks. Habitat features will be recorded as substrate, air temperature, humidity, UV levels, vegetation and habitat size and quality. From this, Helena will be able to determine the habitat supporting the highest number of skinks, which will assist with habitat management and future captive breeding plans.
- Compare the sizes and rates of growth between sub-populations and previous data also analysed, using morphometric data. This will provide a better understanding of the differentiation between sub-populations.
- Take and analyse buccal swabs to determine whether the skinks are genetically as well as morphologically diverse. During the last population studies in 1998 and 2004, it was noticed that skinks from the Castle Harbour Islands were visually distinct from those found on Bermuda’s mainland at Spittal Pond. Since then it has been thought that two genetically distinct populations may exist due to their isolation.
Helena hopes to find out how many Bermuda skinks remain in the wild, understand the dynamics and genetics of the population, and comprehend habitat requirements necessary if captive breeding and reintroductions are to take place in the future.
More information at: www.chesterzoo.org/conservation-and-research/latest-field-news/bermuda-skinks
Helena Turner is a member of the Durrell Institute of Conservation and Ecology.
Chester Zoo Studentship
Bermuda Zoological Society - Eric Clee Environmental Fund