Population ecology of a cryptic arboreal snake (Hoplocephalus bitorquatus)
Michael B. Shelton
A C , Ross L. Goldingay A and Stephen S. Phillips B
+ Author Affiliations
- Author Affiliations
A School of Environment, Science and Engineering, Southern Cross University, Lismore, NSW 2480, Australia.
B Biolink Ecological Consultants, 9 Marshall Street, Uki, NSW 2484, Australia.
C Corresponding author. Email: michaelshelton8@bigpond.com.au
Australian Journal of Zoology 65(6) 383-390 https://doi.org/10.1071/ZO18009
Submitted: 2 February 2018 Accepted: 28 June 2018 Published: 20 July 2018
Abstract
Biologists have traditionally been reluctant to study arboreal snakes due to low rates of capture. Overlooking such taxa can mislead interpretations of population trends for data-deficient species. We used regularly spaced transect searches and standard capture–mark–recapture techniques to describe population structure, growth rates, survival and capture probability in a population of the pale-headed snake (Hoplocephalus bitorquatus) in southern Queensland. We obtained data from 194 captures of 113 individual snakes between 2009 and 2015. Using the Cormack–Jolly–Seber method, we estimated apparent annual survival in subadult snakes at 0.23 ± 0.01 (s.e.) and 0.81 ± 0.08 for adults. Capture probability was estimated at 0.16 ± 0.14 per session in subadult snakes and 0.33 ± 0.06 for adults. Within the red gum forests of our study site, we estimate pale-headed snake density at ~13 ± 7 ha–1. Using von Bertalanffy growth modelling, we predict that snakes reach sexual maturity after about four years and may live for up to 20. Our results suggest that the species is a ‘k’ strategist, characterised by slow maturation and low fecundity. These traits suggest that populations will recover slowly following decline, exacerbating the risk of local extinction.
Additional keywords: capture–mark–recapture, Cormack–Jolly–Seber, Elapidae, population estimate, von Bertalanffy growth modelling.
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