The Christmas Island blue-tailed skink (Cryptoblepharus egeriae) is a Critically Endangered species listed on the EPBC list, endemic to Christmas Island. They are named for the striking blue tail against a small brown body. 

The species is now extinct in the wild on Christmas Island due to introduced predators such as wolf snakes, yellow crazy ants, and other invasive species, combined with impacts from habitat disruption and vulnerabilities associated with the small population. 

Captive breeding and translocations now aim to restore the species to safe, predator-free environments. Remaining individuals are maintained in a Christmas Island captive breeding program, and at Taronga Zoo. There are efforts with assisted colonisation underway to establish populations on two islands in the Cocos Keeling Islands. 
 

Parks Australia aimed to support recovery efforts by using eDNA techniques to detect both the skink and its known cryptic predator – the wolf snake (Lycodon capuchinus). 

EnviroDNA developed and optimised targeted qPCR assays for: 

• Christmas Island blue-tailed skink

• Wolf snake - validated in mesocosm trials (controlled tank environment to mimic their natural habitat). 

Additionally, rat stomach contents were analysed to quantify predation pressure, helping guide predator management strategies.
 

Results

• This project successfully detected the skink in release sites using a qPCR assay, combined with a metabarcoding approach. 

• The information from the rat stomach analysis provided important data to support efforts to plan and protect a new colony of Cocos Keeling Islands skinks being released for reintroduction. 

Want to learn more?

Explore Target Species Detection using eDNA