Search for cryptic Pseudomys shortridgei in suitable habitat in the south-east of South Australia

Abstract

Pseudomys shortridgei has been recorded from a restricted and fragmented distribution across southern Australia. Fossil deposits represented the species in mainland South Australia. However, the discovery of an extant population of P. shortridgei in the lower south-east of South Australia, and its morphological similarity to the more common Rattus fuscipes and R. lutreolus highlighted the need to verify the current distribution of the species. Existing vegetation community and systematic baseline biological survey data were used in a fast, cost-effective and systematic desktop assessment to identify the distribution of potentially suitable habitat. Attributes within 12 spatial layers were assigned a value of ecological relevance, reclassified and combined using weighted overlay analysis in ESRI ArcGIS 9.1. At ground-truthed sites, randomly assigned to the most suitable habitat within the ‘equal weightings’ output, understorey had been poorly represented by available data and some vegetation community classifications were no longer current. Despite this limitation, potentially suitable habitat was located within three remnants and targeted in a small mammal survey. From 1459 trap-nights, only Antechinus flavipes, R. fuscipes, Isoodon obesulus obesulus, Austrelaps superbus and Mus musculus were captured. It is unlikely that P. shortridgei inhabits the remnants targeted; however, further field surveys targeting smaller remnants or vegetation communities poorly represented by existing data used in the desktop assessment are recommended.