Date of Award
Master of Science (MS)
College of Science and Mathematics
Thesis Sponsor/Dissertation Chair/Project Chair
Paul A. X. Bologna
Scott L. Kight
Bottlenose dolphins (Tursiops truncatus) are known to exhibit a range of different social structures and habitat use profiles. To investigate the structure of the population off Cape May, NJ, photo identification techniques were employed. Between April 2013 and November 2014, 209 survey days with 989 individual sightings were observed from a platform of opportunity, the whale watching vessel the American Star. The primary goals of this study were to assess the population size in this area; determine whether or not the inshore ecotype were mixing with the offshore ecotype; determine home range size for dolphins sighted multiple times; and to assess their behavior throughout the day, between trips, and between months.
Using distinct markings on the dolphin’s dorsal fins, data were collected on individuals between 1-3 times daily. Data collected included weather and water conditions, GPS locations, group size, behaviors observed, and presence of calves. The program Flukebook was utilized to help determine population size and help photo identify individual dolphins. The program ArcGIS was used to map home range distances and areas.
The Cape May, NJ dolphin population was estimated at approximately 1,039 individuals. 97 of these individuals were sighted more than once, and 17 of these were observed in both inshore and offshore habitats. The linear home range average for coastal dolphins was 2.75km. The linear home range average for inshore/offshore dolphins was 30.65 km. The average home range areas (dolphins sighted three or more times) for coastal dolphins were 4.1km2, while the average for inshore/offshore dolphins was 217.22km2.
The Cape May population of bottlenose dolphins was observed traveling most often in September in 2013. In both years, traveling had comparable observations. Feeding was observed more often during the morning during 2013, and during the morning and evening trips in 2014. In both years feeding observations decreased as it got later in the season. Mating was observed more often during the morning and during July and August, and fell in September 2013. In 2014, mating was observed more often during the evening, and also decreased after June. Surfing and breaching behaviors showed little to no variation in both years.
This study shows that this population may be less habitat-limited than other populations and that the individuals are utilizing both inshore and offshore habitats. Interactions may be occurring between the two ecotypes, which may include mating, behavior, and culture transfer, especially during the months of June, July, and August. The home range analysis has provided insights into the habitat use of the animals in the area, which is relatively consistent with the published literature. Behaviors were found to be significantly different throughout the day, as well as seasonally. Traveling was seen more during the later months in 2013, which may indicate the dolphins preparing to travel down south. Feeding was seen more often in the mornings in 2013, and more often during the morning and evenings in 2014. Mating was seen more often in the mornings in 2013, and during the evenings in 2014. In both years less mating was seen later in the season, most likely due to females already being pregnant or not wanting to calve during that time the following year. Future research should include a more detailed photoidentification analysis of dolphins sighted in 2014, which focuses on population size, differences in habitats, and behavioral changes from different years.
Talty, Colleen Marie, "Assessment of Behavior, Home Range, Population Size, and Intermixing Among the Atlantic Bottlenose Dolphin, Tursiops truncatus, in New Jersey" (2015). Theses, Dissertations and Culminating Projects. 640.