09 11/09/2017

Ecology and genetics of the Bermuda skink

Chester Zoo Conservation Scholar tells us more about her PhD research

Heléna Turner, a Chester Zoo Conservation Scholar, is using mark-recapture methods to learn more about the Bermuda skinks’ distribution and ecology.

Working in collaboration with Chester Zoo, the Government of Bermuda’s Department of Conservation Services and Manchester Metropolitan University, Heléna is currently studying the Bermuda skink as part of her PhD in Biodiversity Management at The University of Kent. 

Bermudan skink in the wild

Heléna tells us more about her work below:

I’m looking at the conservation and population status of the critically endangered Bermuda skink (Plestiodon longirostris). There is estimated to be only 2,500 remaining in the world and their population has been in continual decline since 1965. The species is listed as Critically Endangered on the IUCN Red List and is facing threats such as habitat fragmentation, predation by invasive predators and pollution.

Not much is actually known about their ecology making Heléna’s work crucial to develop a better understanding of this endemic lizard species.

Helena Turner Chester Zoo Conservation Scholar in Bermuda
Read more from Heléna on our Act for Wildlife blog here >

Heléna carried out five day long field surveys at four different sub-populations. Using large glass jars filled with rotten sardines and cheese to attract the skinks. Heléna and the research team checked the traps every hour during a five hour period, processing crucial information from the captured skinks; including genetic samples, morphometric measurements and other data such as the skinks’ stage of life, their gender and also missing digits or other mutilations which may indicate high predation in the area. Buccal swabs collected on the field are then brought back to the lab to do DNA extractions.

Surveying and sampling in Bermuda, skinks

“I have been doing microsatellite genotyping which involves sequencing the DNA for allelic information. The microsatellite repeats are amplified with fluorescent labelled primers and then the alleles are separated by size. The next step will be to run the data through various software packages to find out if the different sub-populations present genetic differences.

Bermuda skink

“External parasites found in the lizards’ ear cavities are collected as well, in addition of faecal samples that will help determine the presence of internal parasites. These faecal samples are also used to define the skinks’ diet using genetic analysis determining the DNA of their prey items.”

Chester Zoo’s Curator of Lower Vertebrates and Invertebrates at Chester Zoo, Dr Gerardo Garcia, is Heléna’s supervisor. He tells us more:

We also take photographic images of different parts of the skinks’ bodies to see if there are colouration differences between separated populations and to compare them with the individuals at Chester Zoo.

Bermuda skink

Surveying and sampling in Bermuda, skinks

The number of lizards captured on each island varied from around 10 individuals per day on Nonsuch Island up to 40 individuals on Southampton, where invasive species are not as abundant as in the other two islands. Once captured, the lizards were marked in order to gather information on their ecology and distribution. The PIT tags (Passive Integrated Transponders) used gives the animal a unique number that can be easily scanned with the reader using an electromagnetic field and will last the animal’s lifetime.

This mark-capture-recapture method will allow Heléna to gain long term insight into the population dynamics and will provide new information on the skinks’ movement, growth and survival rates which has never been done before for this species.

Heléna’s work runs in parallel to a conservation breeding programme at Chester Zoo in a last gasp attempt to prevent the species being lost forever. We’re also thrilled to share the news that we’ve recently had two clutches of skinks hatch at the zoo - a world first! 

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