Comparative survey techniques for a cryptic Australian snake (Hoplocephalus bitorquatus)
Michael B. Shelton![https://orcid.org/0000-0003-4702-6905](/media/client/orcid_16x16.png)
![https://orcid.org/0000-0002-6684-9299](/media/client/orcid_16x16.png)
A School of Environment, Science and Engineering, Southern Cross University, Lismore, NSW 2480, Australia.
B Corresponding author. Email: michaelshelton8@bigpond.com.au
Australian Journal of Zoology 68(2) 68-75 https://doi.org/10.1071/ZO20062
Submitted: 14 July 2020 Accepted: 14 April 2021 Published: 12 May 2021
Abstract
Ecologists endeavour to develop survey techniques that are cost-effective for the species they target and robust enough for statistical analysis. Using time as a measure of effort, we compared visual encounter surveys with artificial cover objects (strapped to trees), targeting an arboreal elapid, the pale-headed snake (Hoplocephalus bitorquatus) and its potential prey (geckos). Within a red gum forest vegetation community with relatively high snake density, capture rates were 0.6 ± 0.1 (s.e.) snakes/person-hour using visual encounter surveys, compared with only 0.1 ± 0.1 snakes/person-hour using cover objects. The probability of detection of pale-headed snakes was estimated from occupancy modelling at 0.70 ± 0.06 in visual encounter surveys and 0.19 ± 0.09 in cover object surveys. Gecko capture rates (among all vegetation communities) were significantly greater (P < 0.001) using cover objects. The probability of detection of geckos was estimated from occupancy modelling at 0.77 ± 0.05 in visual encounter surveys and 0.97 ± 0.02 in cover object surveys. Geckos favoured (P < 0.001) cover objects facing south during all seasons except winter. Artificial cover objects may provide some value in detecting pale-headed snakes in vegetation communities where habitat resources are limited; however, where resources are plentiful, visual encounter surveys are likely to remain the most cost-effective survey option.
Keywords: Elapidae, arboreal, artificial cover objects.
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