Practical infra-red illumination and observation techniques for wildlife studies using ICI-962 perspex

Abstract

MAMMALS do not normally visually perceive infrared (IR) or ultra-violet (UV) light that exists on either side of the visual spectrum from 390 to 760 nanometers (nm) (Wolken 1975). There is no evidence to suggest that nocturnal mammals have become more sensitive to long wavelength light as an adaptive response (Lythgoe 1979), although some reptiles can sense longer wavelength, thermal IR radiation (Barrett et al. 1970). Because it is not perceived, and is unlikely to affect animal behaviour, IR observation can be an invaluable tool for wildlife researchers. This paper describes the construction and use of simple IR radiation sources that can be used for non-invasive behavioural observations of captive and free-ranging mammals.