Dolphin prey herding: Prey ball mobility relative to dolphin group and prey ball sizes, multispecies associates, and feeding duration

摘要

Prey herding, that is, the foraging tactic of swimming around and under prey balls in an attempt to tighten or move them horizontally or vertically, is common among delphinids (see Wells et al. 1999, Connor 2000, Heithaus and Dill 2002 for summaries). Although some studies have described prey-herding behaviors (e.g., Wursig and Wursig 1980, Simila and Ugarte 1993, Clua and Grosvalet 2001), we understand little about factors that influence duration of dolphin feeding bouts, and the role of intraspecific coordination, prey ball size, and multispecies associations in structuring these foraging behaviors (Stensland et al. 2003, Gowans et al. 2008). Prey movements and availability of alternative prey patches likely influence duration of feeding bouts, whereas intraspecific coordination (Wursig 1986), prey ball size (Schmitt and Strand 1982, Norris and Schilt 1988), and multispecies associates (Evans 1982, Acevedo-Guerrez 2002a) potentially influence prey movements.