Cryptoblepharus egeriae: Difference between revisions

{{short description|Species of reptile}}{{Use dmy dates|date=July 2019}}

{{for|other species sometimes known as blue-tailed skink|Blue-tailed skink (disambiguation)}}{{Speciesbox

'''''Cryptoblepharus egeriae''''', also known [[Common name|commonly]] as the '''blue-tailed shinning-skink''', the '''Christmas Island blue-tailed shinning-skink''', and the '''Christmas Island blue-tailed skink''', is a [[species]] of [[lizard]] in the [[Family (biology)|family]] [[Scincidae]] that was once endemic to [[Christmas Island]]. The Christmas Island blue-tailed skink was discovered in 1888.<ref name=":1">{{Cite journal |author=Boulenger GA|author-link=George Albert Boulenger |date=1888 |title=On the Reptiles of Christmas Island |url=https://zslpublications.onlinelibrary.wiley.com/doi/10.1111/j.1469-7998.1888.tb06729.x |journal=Proceedings of the Zoological Society of London |volume=1888 |issue= |pages=534–536 |doi=10.1111/j.1469-7998.1888.tb06729.x |issn=0370-2774}} (''Ablepharus egeriae'', new species, pp. 535–536).</ref> It was formerly the most abundant reptile on the island, and occurred in high numbers particularly near the human settlement. However, the Christmas Island blue-tailed skink began to decline sharply outwardly from the human settlement by the early 1990s, which coincided with the introduction of a predatory snake and also followed the introduction of the yellow crazy ant (''[[yellow crazy ant|Anoplolepis gracilipes]]'') in the mid-1980s.<ref name=":0">{{Cite journal |last=Emery |first=Jon-Paul |date=2021 |title=The lost lizards of Christmas Island: A retrospective assessment of factors driving the collapse of a native reptile community |url=https://conbio.onlinelibrary.wiley.com/doi/10.1111/csp2.358 |journal=Conservation Science and Practice |volume=3 |issue=2|doi=10.1111/csp2.358 |s2cid=234078176 |hdl=10536/DRO/DU:30147604 |hdl-access=free }}</ref> By 2006, the Christmas Island blue-tailed skink was on the endangered animals list,<ref name=":2">{{Cite web |title=Options beyond captivity for two critically endangered Christmas Island reptiles |url=https://www.nespthreatenedspecies.edu.au/projects/options-beyond-captivity-for-two-critically-endangered-christmas-island-reptiles#:~:text=The%20blue-tailed%20skink%20(Cryptoblepharus,rapidly%20from%20the%20late%201980s. |access-date=2022-03-24 |website=www.nespthreatenedspecies.edu.au}}</ref> and by 2010 the Christmas Island blue-tailed skink was [[extinct in the wild]]. From 2009- to 2010, Parks Australia and [[Taronga Zoo]] started a captive breeding program, which has prevented total extinction of the species.<ref name=":3">{{Cite web |title=Saving the Blue-Tailed Skink |url=http://taronga.org.au/media-release/2019-09-12/saving-blue-tailed-skink |access-date=2022-03-24 |website=Saving the Blue-Tailed Skink {{!}} Taronga Conservation Society Australia |language=en}}</ref>

The Christmas islandIsland blue-tailed skink typically grows to a [[Snout–vent length|snout-to-vent length]] (SVL) of {{cvt|4|–|5|cm|in}}.<ref name=":2" /> It can be identified by its small black body with two yellow stripes running down the skink's back and onto its vibrant blue tail. The skink can use its blue tail to draw a predator’spredator's attention away from its body by separating its tail from its body. The bright color of the skink's tail means predators are much more likely to notice the tail than the skink's black body.<ref name=":1" />

The Christmas Island blue-tailed skink is a forager known as an [[insectivore]].<ref name=":2" /> Its diet primarily consists of [[Cricket (insect)|crickets]], [[Beetle|beetlesbeetle]]s, [[Fly|flies]], [[Grasshopper|grasshoppersgrasshopper]]s, [[Spider|spidersspider]]s, and [[Earthworm|earthwormsearthworm]]s. It will occasionally eat some [[vegetation]], though insects remain its primary source of food. Because of its small size, the Christmas Island blue-tailed skink forages for its food on the ground, over exposed rocks and low-lying vegetation, and will generally only eat prey that are slower moving.<ref name=":4" />

For the Christmas Island blue-tailed skink, the first [[Seasonal breeder|breeding season]] occurs when males and females are approximately one year old.<ref name=":4" /> The Christmas Island blue-tailed skink typically lives for seven years in the wild, six of which are active breeding years. The male Christmas Island blue-tailed skink will demonstrate [[Courtship display|courtship]] behaviour when trying to find a mate. The female Christmas Island blue-tailed skink will emit biochemicals for the males to smell, letting them know that the female is in her fertile stage of [[reproduction]].<ref name=":1" /> Male Christmas Island blue-tailed skinks will often fight each other to win a female mate during breeding season. These skinks are [[PolygynyAnimal sexual behaviour#Polygamy|polygamous]] which increases their chance of having offspring. Once the female Christmas Island blue-tailed skink has been fertilized, being [[oviparous]], it will generally lay two eggs at a time, with a 75-day [[incubation period]].<ref name=":4" />

TheUntil the late 1990s, the Christmas Island blue-tailed skink was [[Endemism|endemic]] to [[Christmas Island]] until the late 1990s when itand could be found all over the island.<ref name=":5" /> It currently exists in captive populations on Christmas Island, at Taronga Zoo, and on a small island (Pulu Blan) in the [[Cocos (Keeling) Islands]] where it has been released as part of an [[Assisted migration|assisted colonization]] trial.<ref name=":3" />

The threat of extinction is largely attributed to introductions of invasive species, including a predatory wolf snake and the yellow crazy ant which were unintentionally brought to the island in the 1980s.<ref name=":0" /> The Christmas Island blue-tailed skink is now extinct in the wild. However, [[Taronga Zoo]] currently has an active breeding program hosted by [[Taronga Conservation Society]], which originated from 66 skinks that were brought into captivity before their population was wiped out.<ref name=":3" /> The breeding program has been running for over a decade, with the goal of releasing some of the skinks back into their native habitat.<ref name=":3" /> Since the Taronga Conservation Society conservation efforts began, 300 skinks have been introduced to the [[Cocos (Keeling) Islands|Cocos Islands]].<ref name=":3" />

The genome of the blue-tailed skink (along with the [[Lepidodactylus listeri|Lister's gecko]]) was sequenced in 2022, marking the first high quality skink reference genome.<ref name=":6">{{Cite journal |last1=Dodge |first1=Tristram O. |last2=Farquharson |first2=Katherine A. |last3=Ford |first3=Claire |last4=Cavanagh |first4=Lisa |last5=Schubert |first5=Kristen |last6=Schumer |first6=Molly |last7=Belov |first7=Katherine |last8=Hogg |first8=Carolyn J. |date=2023 |title=Genomes of two Extinct‐in‐the‐Wild reptiles from Christmas Island reveal distinct evolutionary histories and conservation insights |url=https://onlinelibrary.wiley.com/doi/10.1111/1755-0998.13780 |journal=Molecular Ecology Resources |language=en |pages=1755–0998.13780 |doi=10.1111/1755-0998.13780 |pmid=36872490 |s2cid=257363487 |issn=1755-098X|doi-access=free }}</ref> Analysis of this genome revealed high genetic diversity, reflective of large historical population sizes. However, regions of the genome also showed signs of recent inbreeding, likely because skinks used to found the captive population were somewhat related.<ref name=":6" />