Behavioral Ecology of Deep Diving Odontocetes in The Bahamas

Abstract : This project has provided key baseline information on the behavioral ecology of six cetaceans known from the Bahamas (melon-headed whale, Peponocephala electra; short-finned pilot whale, Globicephala macrorhynchus (Gm); Blainvilles Mesoplodon densirostris, Gervais Mesoplodon europaeus and Cuviers Ziphius cavirostris beaked whales; and sperm whale) to assess potential vulnerabilities to disturbance from Navy activities. All occur sympatrically in deep-water habitats that overlap with Navy sonar use, including at the U.S.Navys Atlantic Undersea Test and Evaluation Center. Data acquired through photo-identification, molecular genetics and chemical biomarkers from tissue biopsies, satellite telemetry, and acoustic recordings were integrated to characterize their population structure and movement patterns, social organization, and foraging behavior. Gm exhibited the most widespread movements while beaked whales demonstrated high site fidelity on a small scale. Long-term and/or complex social structure was revealed for all species studied raising concern for activities that could disrupt key individuals within social units and their resultant effect on the entire unit. Variation across species in their vertical foraging habitat suggests diet differences while the diving capacity of beaked whales enabled them to access upper bathypelagic foraging niches despite their relatively small sizes, but at the cost of reduced dive efficiency. This study provides further support that beaked whales, due to their limited ranging patterns and foraging strategies, may be most vulnerable to disturbances.