Killer Whales: Behavior, Social Organization, and Ecology of the Oceans’ Apex Predators

Social survival: humpback whales (Megaptera novaeangliae) use social structure to partition ecological niches within proposed critical habitat

“…We shall refer to this mutually reinforcing overlap of social-, habitat-, and ecological-partitioning as social niche partitioning. This process has been observed among various vertebrate groups, including terrestrial mammals, e.g., Hapalemur griseus in Madagascar [39], marine mammals, e.g., the sympatric communities of killer whales in the Pacific Northwest and Southern Ocean [31,32] and sperm whales in the Mediterranean [40], as well as in other taxa (see next paragraph). For many such cases, we know that niche partitioning is the direct result of behavioral traits that are socially learned and shared, and thus constitute a form of culturally-mediated niche partitioning [31,[41][42][43][44][45].…”

“…Among the cetaceans, the influence of social-reproductive behavior upon habitat use has been observed in both odontocetes (toothed whales, porpoises, and dolphins) and mysticetes (baleen whales). Examples include nursery groups of dusky dolphins (Lagenorhynchus obscurus) who use shallower waters than other social groups in New Zealand [15], sperm whale (Physeter macrocephalus) populations whose seasonal geography is partitioned by sex and age [16], baleen whales who practice large-scale movements between winter breeding areas and summer feeding areas [17], and specifically humpback whales (Megaptera novaeangliae) who partition breeding habitat according to maternal status and other social factors [18][19][20][21][22][23][24][25][26][27][28][29] Outside of a breeding context, such as foraging, the social component of habitat use may not be recognized unless the species travels within stable family groups (e.g., sperm whales and killer whales, Orcinus orca) or large pods (e.g., tropical dolphins) [16,[30][31][32]. But even for relatively solitary species, foraging and other non-reproductive behaviors still occur within a social context [33].…”

The first three records of killer whales (Orcinus orca) killing and eating blue whales (Balaenoptera musculus)

“…Killer whales ( Orcinus orca ) are apex marine predators, having been documented preying upon nearly every large animal species that swims in the ocean (Ford, 2019; Jefferson et al, 1991). Although they are known to prey on the calves of large whales (Barrett‐Lennard et al, 2011; Ford & Reeves, 2008; Pitman et al, 2007, 2015; Reeves et al, 2006), there is ongoing debate as to whether they can take healthy adults of the largest species (e.g., Mehta et al, 2007; Mizroch & Rice, 2006; Steiger et al, 2008).…”

Social survival: Humpback whales (Megaptera novaeangliae) use social structure to partition ecological niches within proposed critical habitat

“…Outside of a breeding context, such as foraging, the social component of habitat use may not be easily recognized unless the species feeds socially (e.g., [30]) or travels within stable family groups (e.g., sperm whales and killer whales, Orcinus orca) or large pods (e.g., tropical dolphins) [16,[31][32][33]. But even for relatively solitary species, foraging and other non-reproductive behaviors still occur within a social context [34].…”

“…We shall refer to this mutually reinforcing overlap of social-, habitat-, and ecological-partitioning as social niche partitioning . This process has been observed among various vertebrate groups, including terrestrial mammals, e.g., Hapalemur griseus in Madagascar [ 40 ], marine mammals, e.g., the sympatric communities of killer whales in the Pacific Northwest and Southern Ocean [ 32 , 33 ] and sperm whales in the Mediterranean [ 41 ], as well as in other taxa (see next paragraph).…”