Population stability in an unmanaged population of the green and golden bell frog in northern New South Wales, Australia
Ross L. Goldingay
A B , David A. Newell A , Darren McHugh A and Liam Bolitho A
+ Author Affiliations
- Author Affiliations
A School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia.
B Corresponding author. Email: ross.goldingay@scu.edu.au
Australian Journal of Zoology 68(3) 126-135 https://doi.org/10.1071/ZO20101
Submitted: 22 December 2020 Accepted: 25 June 2021 Published: 13 July 2021
Abstract
Population monitoring is required to guide conservation programs. We conducted a capture–mark–recapture study of a population of the vulnerable green and golden bell frog (Litoria aurea) at the northern end of its range. Frogs were captured and marked over three breeding seasons (2015/16, 2016/17, 2017/18) in a large coastal lagoon. We aimed to: (1) produce annual estimates of population size to describe population trajectory, and (2) investigate monthly variation in abundance, capture probability, and temporary emigration to understand how these factors change at a finer temporal scale. Frog abundance varied across the three annual breeding seasons: 60–280 adult males, 120–190 adult females, and 90–420 subadults. We infer that the population is stable because adult abundance estimates were higher after 2015/16. Because our study sampled only half the available breeding habitat, the overall population may number 350–850 adults. Our modelling revealed >40 males but <20 females were detected in the sample area in our monthly samples. Estimates of temporary emigration were high (males: 0.54; females: 0.79), suggesting behaviour that made frogs unavailable for capture between months. Our results suggest that monitoring at greater than annual intervals should be adequate to monitor the future trend of this population.
Keywords: Litoria aurea, threatened frog, multipopulation monitoring, mark–recapture, program MARK, robust design, temporary emigration, population decline, Yuraygir National Park, coastal lagoon.
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