Diane Fraser

The house crow (Corvus splendens): a threat to New Zealand?

The house crow (Corvus splendens), a native of the Indian subcontinent, has shown a rapid expansion of habitat range across Eastern Africa, the Arabian Peninsula, Europe and Asia. It is an adaptable, gregarious commensal bird which is regarded globally as an important pest species due to its impacts on livestock, agricultural and horticultural crops and indigenous fauna and as a fecal contaminator of human environments and water resources. Two Maxent (v3.3.3k) models (A) with presence data in Australia and (B) with simulated entry data locations in New Zealand) and a third ArcGIS model (C) with environmental and social layers) are used to determine an overall suitability index and establish a niche-based model of the potential spatial distribution for C. splendens within New Zealand. The results show that New Zealand, particularly the northern regions of North Island, has suitable environments for the establishment of the house crow. In order of suitability Model B showed highest potential land area suitability (31.84%) followed by Model A (13.79%) and Model C (10.89%). The potential for further expansion of this bird’s invasive range is high and, if New Zealand is invaded, impacts are likely to be significant.

Increasing possum interaction rates with chew cards using new formulation lures

ABSTRACT Measuring the frequency at which brushtail possums (Trichosurus vulpecula) interact with chew cards is a cost efficient way to identify the presence of possums, particularly when at low densities following population reductions. The effectiveness of a new combined olfactory and visual lure, Lure-itTM Spray and Blaze (LISB, Connovation Ltd), was evaluated against the standard flour/icing sugar lure (FIS). A total of 154 alternately lured chew cards were set in a 50 m × 50 m grid over 48 ha of regenerating forest. Possums were detected by 41.0%, 62.1% and 70.5% of chew cards baited with FIS, aniseed laced LISB and cinnamon laced LISB cards, respectively. LISB lures scented with cinnamon or aniseed were significantly more likely to detect possums than FIS lures (odds ratios 3.42 and 2.36, respectively). There was no such difference between cinnamon or aniseed scented lures. Lure-it Spray and Blaze has the potential to increase possum detection rates during surveillance operations.