Alloparental care and social dynamics in the fallow deer (Dama dama)

Abstract: In mammals, a sex difference exists in natal dispersal with females remaining in the natal area and males generally leaving the area of birth. Female groups are regarded as the basic social unit of many mammalian species, and in species with overlapping generations groups may develop a matrilineal structure. Under those conditions where daughters remain in their natal area, altruistic and/or co-operative behaviour may be favoured among both close and more distantly related kin.This thesis examines the social organisation and occurrence of co-operative behaviours in fallow deer populations in southern Sweden. Social groups were often stable in their constitution during and between years and consisted mostly of close relatives, mainly mothers and their daughters. When daughters gave birth they increased their association with their mothers. Alloparental care such as allosuckling and allogrooming, was common, preferably exhibited by older females toward fawns in the social group. All fawns in the group were given milk from alloparenting females but young females behaved more restrictively and approaching fawns were often met with aggression. Allosuckling attempts from fawns from other groups were not tolerated and met with aggression even from old females.Allogrooming, which reduced the number of attached ectoparasites on fawns, was distributed according to relatedness in the stable social unit and not performed towards fawns from other groups. Fawns started to reciprocate both the mother's, other females' and occasionally other fawns' grooming from the age of 8 weeks.Allogrooming between adult females was also performed unidirectionally between close kin members of the same group, or reciprocally between members of different groups in a tit for tat manner with a duration evenly matched between the performers. The results seem to support the notion of kin-based groups in fallow deer, with both kin-selected and reciprocal behaviours.