Changes in Bottlenose Dolphin (Tursiops truncatus) Distribution and Behavior in the Drowned Cayes, Belize, and Correlation to Human Impacts

Human activity can greatly influence the behavior and distribution of bottlenose dolphins (Tursiops truncatus). This project focused on the distribution and behavior of bottlenose dolphins in the Drowned Cayes, Belize. Prior to the 2000s, the area was relatively undeveloped and undisturbed and had minimal human activity. Since 2000, fish camps, small resorts, and cruise ship tourism have flourished in the area. This has caused an increase of over 800,000 visitors from 1998 to 2006. Boat-based survey data were collected from 2005 to 2015 and compared to results from surveys conducted in 1999-2000. Total dolphin observation time as a percentage of total survey time was 17.2% in the 1999-2000 dataset and 10.8% in the 2005-2015 datasets. This decrease in observation time suggests that the dolphin population in the Drowned Cayes has decreased since the late 1990s. However, these values could be influenced by survey methods. In 2015, cruise ship presence in the area was also recorded. Eighty-nine percent of the total observation time for 2015 occurred on days for which there were zero cruise ships present, suggesting that dolphins may be avoiding the area when cruise ships are present. Foraging was the most frequently observed behavior in both 1999-2000 and 2005 to 2015 suggesting that the Drowned Cayes is used as a foraging area. That said, the percent of foraging activity was significantly higher in 1999-2000 (86.3%) than in 2005 to 2015 (57.4%), having dropped by 28.9%. Interestingly, there was a 23.6% increase in traveling behavior between 1999-2000 (9.2%) and 2005 to 2015 (32.8%). These behavioral changes could potentially be linked to increased human activity or other unidentified factors. Examining observed changes in behavior increases knowledge of this species in the study area and can provide insight for improved local management of this small dolphin population