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, parksParks 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 colourcolor 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" />.

== Conservation Effortsefforts ==

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]], inwhich hopesoriginated offrom being66 ableskinks tothat releasewere somebrought ofinto thecaptivity skinksbefore backtheir intopopulation theirwas nativewiped habitatout.<ref name=":3" /> The breeding program has been running for over a decade., Sincewith the Tarongagoal Conservationof Societyreleasing conservationsome effortsof began, 150 Christmas Island blue-tailedthe skinks have been released back ontointo Christmastheir Island,native and 300 skinks were transported to Pulu Blanhabitat.<ref name=":3" /> TheseSince skinks were successfully bred in captivity bythe Taronga Conservation afterSociety Christmasconservation Islandefforts nationalbegan, parks300 rangersskinks werehave been ableintroduced to successfullythe save[[Cocos 66(Keeling) skinksIslands|Cocos before their population was wiped outIslands]].<ref name=":3" />

''C. egeriae'' is most closely related to the [[Cryptoblepharus metallicus|''metallicus'']] group of ''[[Cryptoblepharus]],'' native to Australia, with the estimated divergence of ''C. egeriae'' from the group taking place around seven million years ago,.<ref name=":5">{{Cite journal |lastlast1=Oliver |firstfirst1=Paul M. |author-link=species:Paul M. Oliver |last2=Blom |first2=Mozes P. K. |last3=Cogger |first3=Harold G. |last4=Fisher |first4=Robert N. |author4-link=species:Robert N. Fisher |last5=Richmond |first5=Jonathan Q. |last6=Woinarski |first6=John C. Z. |date=2018-06-30 |title=Insular biogeographic origins and high phylogenetic distinctiveness for a recently depleted lizard fauna from Christmas Island, Australia |url= |journal=Biology Letters |volume=14 |issue=6 |pages=20170696 |doi=10.1098/rsbl.2017.0696 |pmc=6030605 |pmid=29899126}}</ref> It has an XY sex determination system,<ref name=":6" /> which is likely shared across all major skink lineages.