Variation in avoidance of Siberian pine needle oil by rodent and avian species

Siberian pine needle oil, a mixture of potentially repellent compounds, deters feeding in herbivores. To determine its effectiveness as a general vertebrate repellent, we compared the feeding responses of 2 rodent and an avian species to olfactory and oral cues of Siberian pine needle oil. In 2-choice tests, subjects had access to 2 apple pieces, 1 coated with the vehicle solution (vegetable oil) and the other with the repellent solution (Siberian pine needle oil). Deer mice (Peromyscus maniculatus) ingested 1.9 ± 0.1 g of oil-coated apple compared to 0.7 ± 0.1 g of apple adulterated with 10% pine needle oil (P < 0.05). Prairie voles (Microtus ochrogaster) ingested 2.4 ± 0.3 g of oil-coated apple compared to 1.5 ± 0.2 g of apple treated with 10% pine needle oil (P < 0.05). In contrast, European starlings (Sturnus vulgaris) were insensitive to pine needle oil's aversive effect. Prairie voles increased their avoidance of pine needle oil-adulterated apple in 2-choice tests following repeated exposure to the stimuli. However, in 1-choice tests neither oral contact with pine needle oil nor exposure to its volatile cues decreased apple ingestion by prairie voles. Siberian pine needle oil has promise as a rodent control agent when employed in settings where use of a nonlethal product is desirable and alternative food sources are readily available.