Population stability in an unmanaged population of the green and golden bell frog in northern New South Wales, Australia

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.

Don't take my trees: Re‐evaluating the importance of trees when it comes to managing green and golden bell frog, Litoria aurea, habitat

“…However, it is the extent of tree cover and total pond shading that are critical factors that influence the potential for impeded breeding and offspring development. Indeed, we have detected breeding and successful metamorphosis of L. aurea individuals in ponds where the proportion of trees did not result in the complete shading of water (J. Gould, unpublished data, 2022), while other populations within conservation reserves are known to use breeding habitat with extensive tree cover (Daly et al., 2008; Gillespie, 1996; Goldingay et al., 2021). We also did not find evidence in our study that tree presence reduced breeding at ponds or their use by the island population in general, as there was no drop in the likelihood of detecting metamorphs or in counts of post‐metamorphic individuals.…”

“…Despite the calls for managed habitat to be devoid of trees, L. aurea is known to utilize habitat types that naturally include trees, including terrestrial habitats proximal to water (Gillespie, 1996; OEH, 2022). For example, the most northern population in Yuraygir National Park is one of a few that still occupies natural habitat, which is composed of swamp surrounded by trees including Melaleuca and Casuarina (Goldingay et al., 2021; Goldingay & Newell, 2005). We thus suggest that the importance of trees for the species in general has been overlooked, including the potential benefit of trees as microhabitat for prey, hunting, basking, refuge, conspecific and prey avoidance, and for increasing general resource presence and habitat complexity.…”

Multi‐night territorial behavior, chorus attendance, and mating success in red‐eyed treefrogs

“…Using this technique, marked frogs could be scanned at a distance of 3–10 cm from the scanner, without any physical contact. While past studies have used PIT tags to mark wild frogs (Goldingay et al, 2021; Pyke, 2005; Scherer et al, 2005), it is less common to leverage this technology to study the behavior of wild frogs without handling.…”