Mother-infant spatial relations in captive bottlenose dolphins, Tursiops truncatus

The prolonged nursing period and strong, extended mother-infant bond observ ed among bottlenose dolphins may reflect social and physical ontogeny criti cal for infant survival. This study was conducted to quantify ontogentic ch anges in mother-infant contact time and the amount of time infants spent in specific spatial states with their mothers from birth to age 12 mo. These behaviors were studied through a systematic, longitudinal study of six moth er-infant pairs of captive bottlenose dolphins from three different social groups. There was a significant decrease in the time infants spent with the ir mothers (logistic regression, P < 0.001), following the general mammalia n pattern of increasing independence with age. When with their mothers, the probability that infants would be found in "echelon" position, flanking th e mother, decreased as the calf aged (logistic regression, P < 0.001), poss ibly due to anatomical and hydrodynamic factors. The probability that infan ts would be found in "infant" position, underneath the mother, increased wi th calf age (logistic regression, P < 0.001). Results obtained in this stud y are consistent with similar studies of wild bottlenose dolphin mother-inf ant pairs, indicating a suite of ontogenetically comparable behaviors betwe en wild and captive bottlenose dolphins.