Testing the Role of Climate Change in Species Decline: Is the Eastern Quoll a Victim of a Change in the Weather?

Bronwyn A Fancourt,Clare E Hawkins,Stewart C Nicol,Menna E Jones,Christopher N Johnson,Brooke L Bateman,Jeremy Vanderwal,Benjamin Lee Allen

doi:10.1371/journal.pone.0129420

Abstract

To conserve a declining species we first need to diagnose the causes of decline. This is one of the most challenging tasks faced by conservation practitioners. In this study, we used temporally explicit species distribution models (SDMs) to test whether shifting weather can explain the recent decline of a marsupial carnivore, the eastern quoll (Dasyurus viverrinus). We developed an SDM using weather variables matched to occurrence records of the eastern quoll over the last 60 years, and used the model to reconstruct variation through time in the distribution of climatically suitable range for the species. The weather model produced a meaningful prediction of the known distribution of the species. Abundance of quolls, indexed by transect counts, was positively related to the modelled area of suitable habitat between 1990 and 2004. In particular, a sharp decline in abundance from 2001 to 2003 coincided with a sustained period of unsuitable weather over much of the species’ distribution. Since 2004, abundance has not recovered despite a return to suitable weather conditions, and abundance and area of suitable habitat have been uncorrelated. We suggest that fluctuations in weather account for the species’ recent decline, but other unrelated factors have suppressed recovery.

Highlights

Detecting, diagnosing and halting species declines are some of the most challenging tasks faced by conservation practitioners [1]
All statistical analyses were performed using R version 3.0.1 [63]. Both the climate model and the weather model (AUC = 0.755 ± 0.019; Fig 1) provided meaningful predictions of habitat suitability that were consistent with the known distribution of the eastern quoll
The discriminative ability and the broader spatial distribution of suitable habitat were similar for both climate and weather models, differences in suitability were evident at finer spatial scales

Summary

Introduction

Detecting, diagnosing and halting species declines are some of the most challenging tasks faced by conservation practitioners [1]. Action is critical to species recovery [2]. Conservation managers are often forced to act on incomplete knowledge of key threats and factors causing the decline [3]. Unfounded assumptions as to the causal factors can lead to inaccurate predictions of extinction risk and wasted management effort [4, 5]. The eastern quoll (Dasyurus viverrinus) is a medium-sized marsupial carnivore that was once widespread in south-eastern Australia. The last confirmed sighting on the Australian

Methods

Results

Discussion

Conclusion