Castoreum, which is used both in perfume and as a food additive, is a substance derived from the castor sacs of North American and European beavers. In perfume, castoreum lends a smoky, leathery note. Synthetic versions are available, and similar effects can be created using birch tar or cade combined with other plant-based animalic ingredients. At Sonoma Scent Studio we do not use animal ingredients other than beeswax, so our castoreum notes are synthetic or plant-derived.
Photo of North American beaver from wiki.