Biology of the invasive delicate skink (Lampropholis delicata) on Lord Howe Island

Abstract

Lord Howe Island (LHI) is a remote oceanic island in the south-west Pacific that is World Heritage listed due to its diverse, and largely endemic, biota. A suite of introduced species have colonised the island, resulting in the widespread population declines of many native species. The delicate skink (Lampropholis delicata DeVis) was accidentally introduced to LHI from mainland eastern Australia, but there has been no detailed investigation of its biology on the island, or its potential impact on the native biota. We conducted a detailed study of the distribution and biology of the delicate skink on LHI over a six-year period (2007–12). The delicate skink was introduced to LHI in the 1980s, and rapidly spread across the island. It presently occurs in all 21 low-elevation vegetation communities on LHI. The delicate skink is diurnal on LHI, and displays seasonal variation in activity with a peak in November–December. The delicate skink exhibits sexual dimorphism with females having larger body and abdomen sizes and males having longer and broader heads, although the degree of genetic admixture may influence morphology on LHI. Females reproduce in spring and summer (September–February), with a positive relationship between body size and clutch size. Clutch size ranges from 1 to 7 (mean 3.4) and communal egg nests (11–200+ eggs) are common. Tail loss is common on LHI (55%), but is more frequent in adults and females. We conclude that, based on its distribution and abundance, the delicate skink has the potential to impact the diverse and endemic invertebrate fauna on LHI.