The social structure and strategies of delphinids: predictions based on an ecological framework.

摘要: Dolphins live in complex social groupings with a wide variety of strategies. In this chapter we investigate the role that differing habitats and ecological conditions have played evolution delphinid We propose conceptual framework for understanding natural patterns structure which spatial temporal predictability resources influences ranging individuals communities. The predicts when are spatially temporally predictable, dolphins should remain resident relatively small areas. Predictable often found inshore environments where may hide from predators or avoid areas high predator density. Additionally, available food limit group size. Thus, predict there few benefits to forming large groups potentially many being solitary groups. Males be able sequester females, controlling mating opportunities. Observations populations bottlenose (Tursiops sp.) island-associated spinner (Stenella longirostris) seem fit pattern well, along forest-dwelling African antelope primates such as vervets (Cercopithicus aethiops), baboons (Papio sp.), macaques (Macaca chimpanzees (Pan troglodytes). contrast, unpredictable, must range further find necessary resources. Forming only strategy predation, especially open ocean. Larger home ranges likely support greater number individuals; however, prey is sparsely distributed, act reduce foraging competition. Cooperative herding schools advantageous, facilitating formation long-term bonds. Alternately, display short-term affiliations. These make it difficult male males female, polygynandry most strategy. While study wide-ranging delphinids examine these predictions, behavioural has been suggested dusky (Lagenorhynchus obscurus), coastal mixed species Eastern Tropical Pacific. also resemble strategies savannah antelopes desert-dwelling macropods. Resource availability exists distributions will vary. At intermediate-ranging patterns, form mid-sized balancing intra-group competition predation protection. Humpback (Sousa appear pattern, some site fidelity over ranges. They fluid associations other individuals. Predation pressure not sufficiently cause form, probably more by hiding whenever possible. This prevent killer whales (Orcinus orca) but extremely strong bonds within familial altruistic behaviour facilitate life-long bonds, similar those observations sperm (Physeter macrocephalus) elephants (Loxodonta africana). remains largely untested, currently possible describe behaviours, anti-predator tactics sufficient detail appropriate examination ideas. Few studies on conducted explicitly test type framework; existing communities used throughout framework. anticipate present provide starting point hypotheses regarding delphinids.