Mammals--Behavior

Dolphins emit distinct vocalizations in the contexts of stressful situations, such as when captured in nets. It has been assumed among animal rights groups that the presence of human swimmers causes stress in captive Atlantic bottlenose dolphins (Tursiops truncatus). Stress may be expressed in dolphin vocalizations and the associated visual behaviors before, during, and after swim sessions with humans. Thus, these behaviors were recorded to elucidate quantitative vocal patterns suggestive of conspecific stress. Significant differences among vocalization types within sample sessions were found only for whistles between During II and After sessions. Other comparisons indicated no significant differences for vocalization production frequencies between the presence or absence of human swimmers. Additionally, correlations found among the seven vocalization types and all five sample sessions indicated only that one variable, i.e. the presence or absence of human swimmers, was being measured in several different ways (by the different vocalization type production frequencies). Thus, conspecific stress, if indeed it can be measured by vocalization production frequency, does not appear to occur more often in the presence of human swimmers.

Knowing how to keep captive gibbons can have an impact on the field of anthropology and, in turn, improve the care of these animals in captivity. A brachiating structure designed for enriching gibbon habitat was constructed on one of two islands in a captive enclosure. The data collected was analyzed on time spent brachiating compared to time spent on the ground. A key factor in collecting data was the placement of the observer with respect to the proximity of the gibbons being observed. In this study the gibbons spent more time on the grass when observing them at close range. The gibbons spent a greater amount of time on the brachiating structure when observed from a distance. Despite complications in data collection, the gibbons displayed preference for the redesigned structure, and were observed brachiating more frequently on the stable supports than the rope supports in the unmodified enclosure.