Emoia caeruleocauda (De Vis, 1892)
Family: Scincidae Blue-tailed Skink Status: Indigenous Description: Juveniles of this species are nearly black with three distinct yellow to cream colored stripes and a vibrant blue tail. As they age both the stripes and the blue coloration of the tail fade and the ground color lightens. Old adults appear to be a uniform brown though in most cases vestiges of the stripes can be seen upon closer examination. This skink is easily confused with some of the other species of skinks found on the Mariana Islands. The all brown adults look very similar to Carlia though they can be quickly distinguished by counting the number of digits on the hand. Carlia have only four digits while all other skinks in the Mariana Islands have five. This skink appears very similar to Emoia cyanura at all ages. E. cyanura tends to retain its stripes throughout its life and the dorsal stripe extends onto the tail whereas the dorsal stripe of E. caeruleocauda ends rather abruptly at the base of the tail. To definitively tell these two species apart an examination of the underside of the fourth (longest) toe is required. E. cyanura has > than 50 scales on the underside of the forth toe and E .caeruleocauda has between 31 and 34. A hand lens is of great assistance in this task. The only place in the Mariana Islands where these two species are known to be sympatric is Cocos Island off of the southern tip of Guam. Biology: This is the other common skink of the Mariana Islands. It can be found in all habitats though it is most common in shaded woods. In this habitat it is often the most commonly encountered skink. E. caeruleocauda is somewhat arboreal and is often seen on leaves, fronds and trunks one to several meters high. This skink may be competitively displaced by Carlia ailanpalai where they co-occur (McCoid and Henke, 1997). It is relatively less common on Saipan and Tinian possibly due to predation by the introduced shrew Suncus marinus (Rodda and Fritts, 1992). It lays two eggs under rocks and debris or in rotting wood. Hatchlings in Guam are about 23 mm SVL (McCoid 1994) Distribution: Native to New Guinea, Philippines, Melanesia and Micronesia. It has been found on every island in the Marianas. McCoid M. J. 1994. Eggs, Hatchling size, and Oviposition Sites of Lizards on Guam Mariana Islands. Herpetological Review 25(3) 98-100 McCoid M. J., and S. E. Henke. 1997. The Role of Carlia cf. fusca (Scincidae) in the Decline of the Herptofauna of Guam, Mariana Islands. Report to the Biological Resource Division of the U.S. Geological Survey. Rodda, G. H. and T.H.Fritts. 1992.The Impact of the Introduction of the Colubrid Snake Boiga irregularis on Guam's Lizards. Journal of Herpetology 26 (2) 166-164 |