Elliott traps found to be ineffective for the survey of swamp skink (Lissolepis coventryi): a cautionary tale of outdated survey guidelines

Abstract

Context Cryptic (i.e. secretive, elusive or well camouflaged) species are often very challenging to accurately survey. Because many cryptic species are threatened, the development of robust and efficient survey methods to detect them is critically important for conservation management. The swamp skink (Lissolepis coventryi) is an example of an elusive and threatened species; it inhabits densely vegetated, wet environments throughout south-east Australia. The swamp skink occurs in peri-urban areas and faces many human-induced threats including habitat loss, introduced predators and environmental pollution. Effective and reliable survey methods are therefore essential for its conservation. Aims This study aimed to review the current swamp skink survey guidelines to compare the detection success of Elliott traps with two alternative methods: passive infrared cameras (camera traps) and artificial refuges. Methods Detection probabilities for the swamp skink were compared using Elliott traps, artificial refuges and camera traps at two known populations on the Mornington Peninsula, Victoria, Australia. Key results Artificial refuges and camera traps were significantly more successful than Elliott traps at detecting swamp skinks. Conclusions Elliott traps are currently regarded as the standard technique for surveying swamp skinks; however, these traps were the least successful of the three methods trialled. Therefore, the use of Elliott traps in future swamp skink presence–absence surveys is not recommended. Implications Many previous surveys utilising Elliott traps have failed to detect swamp skinks in habitats where they are likely to occur. Our findings suggest that at least some of these past surveys may have reported false absences of swamp skinks, potentially resulting in poor planning decisions. A reduction in the reliance on Elliott trapping is likely to increase future swamp skink detection success, broaden our understanding of this cryptic species and aid conservation efforts. Our results emphasise that it is essential to regularly review recommended survey methods to ensure they are accurate and effective for target species.