An Inventory of Peer reviewed Articles on Killer Whales (Orcinus orca) with a Comparison to Bottlenose Dolphins (Tursiops truncatus)
The welfare of killer whales (Orcinus orca) has received worldwide attention recently. The purpose of this study was to sample the peer reviewed scientific research on killer whales with a complementary comparison to Atlantic bottlenose dolphins (Tursiops truncatus) to ascertain the primary topics of research conducted with these two cetaceans. A second objective of the study was to assess the relationship between the research topic and the setting in which the research was conducted. From a database driven search of peer reviewed academic journal articles, 759 unique articles involving killer whales, 2,022 unique articles involving Atlantic bottlenose dolphins, and 38 additional articles that included both species were retained for analysis. Coders categorized each article by topic (Anthropogenic Response, Cognition, Distribution, Echolocation, Foraging/Predation, Health/Physiology, Interactions with Humans, Sociality, and Vocalization) and research setting (Natural Habitat, Captivity, or Both) Most studies of killer whales involved animals in their natural habitat (90% and the majority of killer whale studies, regardless of setting, concentrated on health and physiology, such as contaminants and genetic variability (31% foraging and predation behaviors (26% and geographic distribution (20% The majority of the studies (68% involving bottlenose dolphins were also conducted in their natural habitat, but there was significantly more research comparatively with captive animals and with greater diversity. The results suggested that research with killer whales has been dominated by a limited range of topics with relatively little research conducted on topics that directly address issues of welfare. Similar to killer whales, research with Atlantic bottlenose dolphins has been dominated by health and physiology (48.5% and distribution (17.6% In contrast to killer whales, topics such as sociality (9.5% and cognition (5% were more prominent in research incorporating Atlantic bottlenose dolphins. Both species are still in need of additional research on questions related to behavioral patterns.