Sibling recognition in the beaver: A field test for phenotype matching

Abstract

The hypothesis of kin recognition by phenotype matching predicts that relatives can be identified without previous contact, and/or that cues used for recognition can be learned indirectly from a third but related individual. This hypothesis was tested in the field using 22 beaver, Castor canadensis, families. Individually identifiable beavers were provided with a two-way choice between two experimental scent mounds, one of which was scented with the anal gland secretion (AGS) from an unfamiliar sibling of the test subjects, the other with AGS from an unfamiliar non-relative. Beavers showed less strong territorial responses to AGS from their siblings than to that from non-relatives. The mates of the test subjects, which were not related to, or familiar with, either of the AGS donors, also responded less strongly to the AGS from their mates' siblings than to that from other unfamiliar non-relatives. This discrimination was not shown when castoreum samples were tested instead of AGS. Therefore, it was concluded that (1) information about kinship in the beaver is coded in the AGS but not in the castoreum, (2) the mechanism of phenotype matching is used in beaver sibling recognition, and (3) the cue used in phenotype matching can be learned and used for recognition of related individuals by an unrelated individual.