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Orcas or killer whales (Orcinus orca) are among the most cosmopolitan cetaceans on the planet (Rice, 1998). In the semi-enclosed sea of the Gulf of California in Mexico (Figure 1a), sightings of orcas are considered relatively frequent year-round. However, little is known about their ecology and hunting behavior in this region (Guerrero-Ruiz et al., 1998, 2007; Niño-Torres et al., 2011).
Worldwide, orcas feed on a wide variety of prey, including marine mammals, sea birds, sea turtles, bony and cartilaginous fish, and cephalopods (Fertl et al., 1996; Nichol & Shackleton, 1996; Dahlheim & Heyning, 1999; Ford & Ellis, 2014; Vargas-Bravo et al., 2020). Although as a species they display a generalist foraging behavior, local groups or ecotypes of orcas typically specialize on a small range of available prey (Ford et al., 1998). To efficiently track and hunt target prey in multiple regions around the world, orcas use specialized techniques, including intentional beaching to capture South American sea lions (Otaria byronia) and southern elephant seals (Mirounga leonina) in the Atlantic and South Indian Oceans (Lopez & Lopez, 1985; Guinet, 1992); the production of surface waves to wash crabeater (Lobodon carcinophaga) and Weddell seals (Leptonychotes weddellii) as well as an Adélie penguin (Pygoscelis adeliae) off ice flows in the Antarctic Peninsula (Visser et al., 2008; Pitman & Durban, 2012); "karate chopping" thresher (Alopias vulpinus) and hammerhead (Sphyrna zygaena) sharks (Visser, 2005); cooperative herding of fish into a tight ball (using different techniques, including flashing their white undersides and releasing air bubbles) and stunning them with tail slaps in Norway (Similä & Ugarte, 1993); and cooperatively chasing and disabling large whales, dolphins, and schooling fish (Dahlheim & Heyning, 1999; Baird, 2000).
Hunting specializations are considered important for top predators, especially in cases where prey can cause injuries (e.g., stingrays with their spine, sharks with their teeth), mortality, stranding (Duignan et al., 2000; Visser, 2005; McFee & Lipscomb, 2009; Burdett & Osborne, 2010), or, in general, when a certain resource involves risks representing foraging costs (Lopez & Lopez, 1985; Ford & Reeves, 2008; Mukherjee & Heithaus, 2013). Orcas have been observed feeding on sharks and rays in different parts of the world (Table 1), and specific ray hunting tactics have been documented in New Zealand, including the use of the...