Premium
Juvenile Richardson's Ground Squirrels (Spermophilus richardsonii) Manifest Both Littermate and Neighbour/Stranger Discrimination
Author(s) -
Hare James F.
Publication year - 1998
Publication title -
ethology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.739
H-Index - 74
eISSN - 1439-0310
pISSN - 0179-1613
DOI - 10.1111/j.1439-0310.1998.tb00048.x
Subject(s) - juvenile , agonistic behaviour , agonism , zoology , context (archaeology) , bonobo , psychology , biology , ecology , developmental psychology , aggression , paleontology , politics , political science , law
Newborn ground squirrels (Spermophilus spp.) are reared in isolation of individuals belonging to other litters. At or near weaning, they broaden their social interactions to encompass conspecifics other than littermates. In laboratory studies, juvenile ground squirrels commonly discriminate littermates from non‐littermates, but few studies have examined whether behavioural discrimination at that level persists under natural circumstances. Previous studies have also all but ignored the possibility of alternative levels of social discrimination augmenting or replacing the discrimination of littermates from non‐littermates. To examine those possibilities, I staged interactions in a neutral arena between littermate, neighbour and non‐neighbour (stranger) pairs of otherwise free‐living juvenile Richardson's ground squirrels (Spermophilus richardsonii). Littermates interacted more frequently than other pair types and showed the highest proportion of cohesive behaviour and the least agonism. Strangers interacted less frequently than all other pair types, showed the fewest recognitive contacts, and were the least cohesive and most agonistic. Neighbours interacted less than littermates, but more than strangers, and showed intermediate levels of cohesion and agonism. Neighbours also engaged in more recognitive contacts than strangers, but did not have fewer recognitive contacts than littermates. Defecation rates also differed among interactant types: littermates left the fewest scats in the arena, neighbours deposited an intermediate number and strangers defecated the most. My results substantiate those of earlier laboratory studies suggesting that the discrimination of littermates from neighbouring juveniles persists in the natural context. These data also extend those earlier findings by demonstrating that juveniles come to discriminate neighbours from strangers. Comparisons of the behaviour of related vs. unrelated neighbours reveal that neighbour/stranger discrimination is contingent upon differential familiarity. Simultaneous social discrimination at the levels documented could promote kin‐biased behaviour and cooperation among both related and unrelated neighbours.