Protecting trapped animals from heat exposure: the influence of shading on temperature within small metal box traps

Abstract

Animal research guidelines recognise that trapped animals can potentially be subjected to heat stress, but recommendations are limited to avoiding exposing traps to weather extremes. Intuitively, shading metal box traps should be beneficial in warm to hot climates. Temperatures inside metal box traps were measured within traps located in direct sunlight concurrently with ones covered with artificial shading. Additionally, comparisons were conducted in continuous shade cast by ground-cover vegetation, and in stippled sunlight under an artificial lattice. Deep continuous shade from vegetation was most effective and able to keep traps within 5°C of ambient. Artificial shading using dark shade cloth could actually elevate trap temperatures above that in uncovered traps when exposed to direct sunshine. Reflective foil insulation cover not only provided rain protection for traps but was the most effective shading method trialled for reducing both the rate at which traps heated after sunrise and the maximum temperature reached during the day when exposed to direct sunshine. The use of foil sleeves can provide an extra level of protection from excessive heat exposure to trapped animals, keeping trap temperatures as much as 15°C lower than unprotected traps.