Castoreum Castoreum Castoreum is a yellowish exudate from the castor sacs of the mature North American beaver ("Castor canadensis") and the European beaver ("Castor fiber"). Beavers use castoreum in combination with urine to scent mark their territory. Both beaver sexes have a pair of castor sacs and a pair of anal glands, located in two cavities under the skin between the pelvis and the base of the tail. The castor sacs are not true glands (endocrine or exocrine) on a cellular level, hence references to these structures as preputial glands, castor glands, or scent glands are misnomers. It is used as
Castor Bay the bay, running towards the south. A small bark and grass area with several large pohutukawa trees offering shelter compliments the beachfront and an extended coastline stretches out to the north towards Campbells Bay. Nearby John F. Kennedy Park contains old World War II bunkers that were used to survey the Hauraki Gulf and is accessible from Castor Bay by road (Beach Road) or by walkway (from the extended coastline to the north). The northern headland of Castor Bay is the site of an old Maori pā, Rahopara, that is believed to have been last inhabited and then abandoned in