Pectoral Fin Contact Between Dolphin Dyads at Zoo Duisburg, with Comparison to Other Dolphin Study Populations

Abstract

Tactile exchanges using the pectoral fin have been noted in a variety of dolphin species. In this study, bottlenose dolphins (Tursiops truncatus) at Zoo Duisburg in Germany were seen to exchange pectoral fin contact much like both wild and captive dolphins. The rate of overall contact (touches and rubs) was slightly larger among the Zoo Duisburg dolphins than for three other study sites, although relative rates for contact via rubs and touches by Zoo Duisburg dolphins appears similar to that of dolphins at the other study sites. Pectoral fin contact between Zoo Duisburg dolphins was more similar to that of dolphins at the Roatan Institute for Marine Sciences in that there was no difference in whether the dolphin was rubber or rubbee when initiating pectoral fin contact, although at all sites, including Zoo Duisburg, the rubber was more often the initiator of a pectoral fin contact. More similar to both wild groups, but not the other captive group of dolphins, Zoo Duisburg dolphins had a strong preference for the horizontal body posture when exchanging pectoral fin contacts. The most striking result is that all dolphins studied have a strong preference for body part contacted: when the rubbee is initiator, the top three body parts most contacted by all dolphins include the face, rostrum, and side. Similarly, when in the role of rubber initiator, the top most contacted and third most contacted body parts are identical at all four study sites. The exchange of contact via the pectoral fin seems to be a conserved action with respect to form and function across dolphin species regardless of the environment in which the dolphins reside.