RECIPROCAL ALLOGROOMING IN WILD IMPALA LAMBS

Adult impala engage in a form of reciprocal allogrooming distinguished by a high degree of reciprocity and lack of influence of dominance or relatedness on partner preference or distribution of grooming between partners. A previous study on reciprocal allogrooming of captive newb orn impala lambs in a zoological park found that the allogrooming emer ged as early as the first week after birth and was identical in struct ure and reciprocity to allogrooming in adults. Because these findings of apparently unique allogrooming behavior of newborn impala could hav e been a reflection of the effects of being born and raised in a small , stable captive herd, ii was necessary to investigate reciprocal allo grooming in newborn impala in the wild. The emergence, reciprocity, ra te, and partner distribution of reciprocal allogrooming in wild newbor n impala were observed at two study sites: a national park in Zimbabwe and a game farm in South Africa. Maternal one-way grooming between mo ther and newborn emerged as distinct from reciprocal allogrooming and rapidly declined after week 1 postpartum. Reciprocal allogrooming by l ambs was first seen between 5 and 8d postpartum, and as soon as the be havior occurred it was the same basic pattern as seen in adult impala. The reciprocity index for lambs was near 0.5, indicating that lambs d elivered as much grooming during an encounter as the partner. Lambs we re groeming frequently with non-mother adults and other lambs by week 1 or 2; by week 3 and onward the allogrooming rate of lambs was more t han twice that of their mothers, as predicted by the body size princip le of the programmed grooming model. The strong predisposition of neon atal impala lambs to deliver reciprocal allogrooming as early as the f irst or second meek postpartum would appear to reflect a genetically a cquired adaptation to the threat of tick infestation in their natural habitat.