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Ecology, management and conservation in natural and modified habitats
RESEARCH ARTICLE

Demographic estimates to assess the translocation of a threatened New Zealand amphibian

Javiera Cisternas https://orcid.org/0000-0001-5398-6836 A B * , Luke J. Easton C , Jennifer M. Germano D and Phillip J. Bishop B
+ Author Affiliations
- Author Affiliations

A Aumen o el eco de los montes, NGO, Coyhaique, Chile.

B Department of Zoology, University of Otago, Dunedin 9054, New Zealand.

C Department of Conservation, Whakapapa, Mt Ruapehu 3951, New Zealand.

D Department of Conservation, Nelson 7010, New Zealand.


Handling Editor: Thomas Prowse

Wildlife Research 50(1) 47-56 https://doi.org/10.1071/WR21066
Submitted: 4 November 2020  Accepted: 18 April 2022   Published: 18 July 2022

© 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing

Abstract

Context: Leiopelma archeyi is a threatened New Zealand amphibian species translocated for conservation purposes. A disease outbreak triggered the translocation of 70 frogs to Pureora Forest in 2006 to establish a new wild population of L. archeyi. Ten years after, 60 more frogs were translocated to this site to enhance the genetic and demographic profile of L. archeyi in Pureora Forest. Here, we analysed 14 years of capture–recapture monitoring data collected for this translocated population.

Aims: Our aim was to estimate population demographic parameters that allow us to assess the demographic performance of this translocated population.

Methods: We used spatially explicit capture–recapture (SECR; also called spatial capture–recapture) multi strata/session models to estimate population density and derive its rate of change over time.

Key results: Here we show that the density of translocated Leiopelma archeyi in Pureora (central North Island, New Zealand) remains stable for most of the study period. After the release of 70 frogs in 2006, density varied from 0.02 frogs/m2 in April 2007 to 0.06 frogs/m2 in December 2014. After the second release of 60 frogs in 2016, density in Pureora of L. archeyi varied from 0.21 frogs/m2 in November 2016 to 0.63 frogs/m2 in November 2018.

Conclusions: The study species is a long-lived k-selected species, therefore long-term monitoring (>20 years) is required to corroborate demographic indicators. Nevertheless, as the current density estimates are higher than the density estimated for this population after each release (April 2007 and November 2016), we suggest progress towards the establishment of a new wild population of L. archeyi in Pureora Forest.

Implications: Translocations are a useful conservation tool for many threatened species and post-release monitoring data are the main source of information needed to empirically prove their success.

Keywords: amphibian conservation, conservation translocation, density estimation, Leiopelma archeyi, Leiopelmatidae, monitoring, population management, spatial capture–recapture, spatially explicit capture–recapture.


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