The Ingestion of Artifically Coloured Grain by Birds, and its Relevance to Verebrate Pest Control

Abstract

In 23 field and aviary trials with several species of ground-feeding birds, the short-term uptake of grain coloured red, blue, green, yellow and black was compared with that of natural (uncoloured) grain. In all trials, one or more of the artificial colours caused a significant depression in the amount of food eaten. Although the preferences for grain of the five colours varied from trial to trial, the uptake of both blue and green grain was significantly lower than for untreated grain in all trials, and that of black, red and yellow grain was significantly lower than the control in 22, 19 and 15 trials respectively. Uptake of both blue and green grain was often significantly lower than that of the other three colours. Crimson rosellas, Platycercus elegans, which were fed on blue grain for 3 weeks before being presented with the full range of coloured and natural grain showed some association of the unnatural colour with food. They did not do so when pre-fed for less than 7 days. The possible use of coloured lethal baits to increase target specificity in the control of mammalian pests is discussed.