Effectiveness of volatile irritants at reducing consumption of eggs by captive coyotes

Egg predation by mammalian predators can significantly reduce recruitment of ground-nesting birds. We hypothesized that we could teach predators not to open eggs by giving them prior exposure to eggs injected with volatile trigeminal irritants. To test this, we examined the effectiveness of 10 such chemicals in reducing food and egg consumption by coyotes (Canis latrans). The subjects did not significantly reduce their consumption of food when 1 of the chemicals was placed beside it. However, following injection into eggs, 9 of 10 chemicals significantly reduced the amount of egg consumed by coyotes, 7 increased the time coyotes spent before opening the egg, and 3 (pulegone, allyl sulfide, cinnamaldehyde) decreased the average time of food consumption. These results suggest that a chemical must be directly associated with a food item to reduce its consumption by coyotes. Additionally, coyotes continued to consume untreated food and eggs during posttreatment trials. Further trials are needed to investigate the potential of treating avian nests or producing dummy eggs that facilitate a generalized avoidance of eggs. In these situations, pulegone or cinnamaldehyde may have potential for deterring predation of eggs by canids.