Social and genetic relationships among individuals in urban kit fox social groups

Abstract

Smaller canids, such as most foxes, individually hunt small prey, and therefore social groups typically consist of just a mated pair. However, these smaller canids occasionally form groups in which the members have been presumed to be genetically or socially related. We studied social and genetic relationships among urban San Joaquin kit fox (Vulpes macrotis mutica Merriam, 1888) groups in Bakersfield, California. Of 59 groups, 42.4% had extra adults in addition to the parents. Foxes were field classified as either mothers, fathers, helpers (extra adults), or pups. We then assessed relatedness of foxes within social groups using 11 microsatellites in DNA from tissue or hair samples. Mated pairs were significantly less related than mothers and helpers, with fathers and helpers being intermediate. Twelve pairs of females were mother-daughter dyads but we also found two cases of sisters and two cases where the females were unrelated. Pups were always related to a female identified as their mother. Father-pup pairs were less related than mother-pup pairs, with helper-pup pairs being intermediate. The extra-pair paternity rate (multiple fathers per litter) was 39%. The social flexibility exhibited by kit foxes may increase their resiliency to marked fluctuations in resource availability thereby reducing extinction risk.