. The Canadian field-naturalist. 1989 Notes 427. Figure 1. Transient Killer Whale X10 at Race Rocks, British Columbia, 12 October 1987. Photo bv Robin W. Baird. It is possible that the sea lions did not recognize the atypical whale as a Killer Whale. We suggest that sea lions respond to visual cues, such as the dorsal fin of a Killer Whale, which match a perceptual search image. Although sea lions may be formidable prey for a lone Killer Whale, lone Killer Whales have previously been observed preying on sea lions (Lopez and Lopez 1985). Recognition of a predators' behavioural state has been no
. The Canadian field-naturalist. 1989 Notes 427. Figure 1. Transient Killer Whale X10 at Race Rocks, British Columbia, 12 October 1987. Photo bv Robin W. Baird. It is possible that the sea lions did not recognize the atypical whale as a Killer Whale. We suggest that sea lions respond to visual cues, such as the dorsal fin of a Killer Whale, which match a perceptual search image. Although sea lions may be formidable prey for a lone Killer Whale, lone Killer Whales have previously been observed preying on sea lions (Lopez and Lopez 1985). Recognition of a predators' behavioural state has been noted as an important factor in reaction to predators by terrestrial ungulates (Estes and Goddard 1967; Kruuk 1972; Schaller 1972). From our observation we suggest that it is unlikely the sea lions recognized the whales' behavioural state since they did not react. As the Killer Whales in an area may be members of more than one breeding population (Bigg et al. 1987; Baird and Stacey 1988b), some of which specialize in feeding on fish, proximity of Killer Whales to other marine mammals may not always be perceived as a potential threat by the latter. Dolphin (1987) reports non-aggressive Humpback Whale {Megaptera novaeangliae) — Killer Whale interactions in Alaska, but unfortunately fails to mention if the Killer Whales observed were the resident type, which feed primarily on fish, or the transient type. Marine mammals have been reported in close proximity to resident Killer Whales in British Columbia, showing no apparent reaction (Jacobsen 1986). However, even in the presence of resident Killer Whales, sea lions may show interest with an increase in vigilant behaviour (Jacobsen 1986). Killer Whale attacks on marine mammals usually elicit a variety of escape responses (eg. Steltner et al. 1984; Lopez and Lopez 1985). These observations suggest that there may be a variety of cues influencing the reactions of marine mammals to Killer Whales. Further research on the perceptual proces
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