Social Change in Cetacean Populations Resulting from Human Influences

Abstract

Group living has a number of potential ecological and animal welfare benefits. The social environment of the 90 or so species (http://www.iucn-csg.org/index.php/status-of-the-worlds-cetaceans/) of cetaceans is highly diverse, ranging from the complex third-order alliances of male bottlenose dolphins (Tursiops sp.), to the matrilineal societies of pilot whales (Globicephala sp.), to the apparently less social beaked whale species. Nevertheless, even for some beaked whales, there is evidence of stable group associations. For larger, long-lived or wide-ranging species, such as blue whales (Balaenoptera musculus), there are also important spatio-temporal considerations for interpretation of behaviour and associations. As a result of the differing social structures and the opportunity for the transmission of social information, the relationship between sociality and welfare in this order of mammals is multifaceted. Sociality and social dynamics have the potential to influence individual and group welfare in both a positive and negative manner, and there are complex relationships between sociality, the impacts of human-induced rapid environmental change and the welfare of cetaceans. E.O. Wilson listed ten ‘qualities’ of sociality. Although used to classify animal societies according to their degree of sociality, some of these features also provide a useful roadmap for evaluating the importance of sociality for individual and group welfare. They are used here to examine the interplay between sociality, welfare and environmental change. The importance of the transmission of social information, culture and specific behaviours, such as play, is also explored within the context of environmental change and cetacean welfare. It is concluded that a more comprehensive understanding of the social mechanisms operating within and between cetacean social groups will enable a fuller understanding of the welfare implications of human-induced rapid environmental change. Alongside more traditional measures of welfare, such as body condition and disease, aspects of sociality may also provide important indicators for establishing welfare condition in these highly social species.