Two groups (n=6 and n=7) of Eurasian wolves (Canis lupus) were observed at Kolmården Wildlife Park, Sweden, between May and August 2015.
At each experimental day, five wooden logs were impregnated with one of the following odor stimuli:
- Horse blood
- Blood component (Trans-4,5-epoxy-(E)-2-decenal)
- Fruity odor (Isopentyl acetate)
- Near odorless solvent (Diethyl phthalate)
Each of the four odor stimuli was presented five times to each of the two wolf groups. The logs were only presented on non-rainy days and non-feeding days. As it was not possible to have a full overview of the whole enclosure, the logs were attached to separate chains anchored in trees outside the enclosure, to prevent the animals from removing the logs out of sight.
The animals were observed for three hours in the morning and three hours in the afternoon on a given experimental day. The behavioral responses were recorded using continuous sampling.