Diet of Bottlenose Dolphins Tursiops truncatus in the Northwest Panhandle and Foraging Behavior Near Savannah, Georgia

• Main Author: Bowen, Sabrina Rose
• Format: Dissertation
• Language: English
• Published: 01.05.2011
• Subjects: Biology; Conservation; Ecology

The foraging ecology of bottlenose dolphins Tursiops truncatus in the Northwest Florida Panhandle and estuaries in northern Georgia was determined using diet analysisand behavioral surveys. Stomach content analysis was completed on bottlenose dolphins(N = 25) that stranded in the Northwest Florida Panhandle from November 2006 toMarch 2009. The most abundant prey species were spot Leiostomus xanthurus (20.4%), squid (10.9%), pinfish Lagodon rhombiodes (10.3%), and Atlantic croakerMicropogonias undulatus (8.5%). Dolphins that stranded during months with a red tide Karenia brevis bloom consumed more pinfish, and spot; whereas dolphins that strandedin non-bloom months consumed more squid, Atlantic croaker, and silver perch Bairdiella chrysoura. Differences in diet were also identified for dolphins that stranded insidebays/sound and dolphin that stranded outside of bays along the coast, and male and female dolphins. Surveys were conducted from south of the Savannah River to north ofOssabaw Sound in Georgia where foraging behaviors were classified. Multivariate Generalized Additive Models were used to test correlations of behaviors to dolphin groupsize, depth, salinity, temperature, creek width, and tide. Sightings with headstands (p = 0.009), hard stops (p = 0.019), chasing (p = 0.004), mudbank whacking (p < 0.001), herding/circling (p = 0.024), and strand feeding (p = 0.006) were correlated with shallow water or small creeks. Sightings with kerplunking (p = 0.031), mudbank whacking (p = 0.001), strand feeding (p = 0.003), and herding/circling (p = 0.026) were significantly correlated with low tide. The results of the Savannah, Georgia study were the first tocharacterize foraging behaviors in this area and demonstrate how bottlenose dolphins utilize the salt marsh estuary in terms of foraging. Studies like these are important to determine how dolphins forage efficiently and to provide background information on diet and foraging behavior for use in monitoring future impacts to dolphins in the Northwest Florida Panhandle and near Savannah, Georgia.