Observations of rough-toothed dolphins (Steno bredanensis) off the coast of Utila, Honduras

Abstract

Local dive shop operators and fishermen report that rough-toothed dolphins (Steno bredanensis) are frequently encountered off the coast of Utila, Honduras, (16°05'46.5"N 86°55'47.8"W). Our observations suggest that at least some of these animals may constitute a resident population, although the extent of the resident group's home range has not been determined. Twenty-eight rough-toothed dolphins were identified using photo-identification techniques, 15 of which were re-sighted on two or more occasions. The 12 animals that were re-sighted four or more times were typically seen together, suggesting that they constitute a stable social group. At least one of these dolphins is an adult male, and his continued presence in this social group may reflect a social structure for rough-toothed dolphins that differs from that described for other dolphin species. Social interactions often involved tactile behaviours such as pectoral fin rubbing and side rubbing. The observed dolphins sometimes expressed interest in the research vessel and other boats by approaching, and on separate occasions examined a hydrophone and slow moving propeller visually and echoically. Overall, our behavioural observations suggest: (1) synchronous behaviours and ‘tight’ groupings are common while rough-toothed dolphins are travelling; (2) tactile contact is an important aspect of social interactions for rough-toothed dolphins; (3) cooperative behaviour occurs during play; and (4) rough-toothed dolphins are curious.

Pelagic or insular? Genetic differentiation of rough-toothed dolphins in the Society Islands, French Polynesia

“…However, they are also known to use near-shore waters (within a few nautical miles) especially near oceanic islands, in areas of steep bathymetric relief (Gannier and West, 2005;Nekoba-Dutertre et al, 1999;Poole, 1993;Ritter, 2002). Although their pelagic habitat could suggest a nomadic way of life, several studies based on photo-identification have shown high levels of re-sightings, suggesting the presence of resident populations around islands Johnston et al, 2008;Kuczaj and Yeiter, 2007;Mayr and Ritter, 2005;Nekoba-Dutertre et al, 1999). In addition to site fidelity, limited dispersal was also found between two populations of rough-toothed dolphins around the island of Hawai'i and Ni'ihau/Kaua'i (Baird et al, 2008a).…”

Marine Mammals of the Gulf of Mexico

“…We know that they have a very large brain-to-body ratio, and the few that have been kept in captivity have been noted to be extremely flexible behaviorally (i.e., intelligent), with evidence for sophisticated second order learning (also called deutero-learning), which implies thought (Pryor et al 1969). Recent work (Kuczaj and Yeater 2007) indicates that they have tight social bonds with long-term relationships.…”

Distribution and Abundance Estimates for Cetaceans in the Waters off Guam and the Commonwealth of the Northern Mariana Islands

“…The rough-toothed dolphin is often regarded as an offshore species that prefers deep waters; however, it can occur in waters with variable bottom depths (e.g., Gannier and West, 2005;Kuczaj et al, 2007). It rarely occurs close to land, except around islands with steep drop-offs nearshore (Mignucci-Giannoni, 1998;Gannier, 2000;Ritter, 2002;Gannier and West, 2005;Kuczaj et al, 2007).…”

“…It rarely occurs close to land, except around islands with steep drop-offs nearshore (Mignucci-Giannoni, 1998;Gannier, 2000;Ritter, 2002;Gannier and West, 2005;Kuczaj et al, 2007).…”