The social organization of resident-type killer whales (Orcinus orca) in Avacha Gulf, Northwest Pacific, as revealed through association patterns and acoustic similarity

Abstract

Northeast Pacific resident-type killer whales (Orcinus orca) are known to form stable associations based on kinship between maternal relatives (matrilines) with a system of vocal dialects thought to reflect kinship relationships. We analyzed association patterns and acoustic similarity to study the social organization of killer whales in Avacha Gulf (Kamchatka, Russia), in the Northwest Pacific. The resident-type killer whales of Avacha Gulf formed temporally stable units that included maternal relatives with no dispersal observed. Acoustically, the killer whale community of Avacha Gulf was characterized by a system of dialects comparable to the communities of Northeast Pacific residenttype killer whales. Different units rarely associated with each other and these associations were nonrandom. Associations at different spatial levels did not always coincide with each other and with the patterns of acoustic similarity. Associations between units could change quickly irrespective of kinship relationships. The vocal dialect of a unit, which is more stable than the association patterns between units, might better reflect the overall kinship relationships. The stability and frequency of associations between units depended on the number of mature males in a unit, which could contribute to differences in the speed of change in vocal dialects and association patterns.

Using platforms of opportunity to determine the occurrence and group characteristics of orca (Orcinus orca) in the Hauraki Gulf, New Zealand

“…This study reported six encounters with a single orca in the HG. Similar findings of lone orca have been reported in Alaska, USA (Maniscalco et al 2007), Argentina (Lopez & Lopez 1985;Iñíguez et al 2005), southeastern Brazil (Santos & Netto 2005Santos & da Silva 2009;Lodi & Farias-Junior 2011), Kamchatka, Russia (Ivkovich et al 2010), Marion Island (Condy et al 1978), Pacific northwest (Ford & Ellis 1999), Papua New Guinea (Visser & Bonoccorso 2003), Peru (García-Godos 2004), Vancouver Island, Canada (Bigg 1982) and West Africa (Weir et al 2010). However, solitary orca have not previously been encountered in Using platforms of opportunity 11 New Zealand waters (Visser 2000(Visser , 2007.…”

“…In Papua New Guinea, groups of three individuals were the most sighted (n = 15; Visser & Bonoccorso 2003). Ivkovich et al (2010) indicated that the mean group size for orca in Avacha Gulf, Russia, northwest Pacific, was six individuals.…”

Cultural evolution of killer whale calls: background, mechanisms and consequences

“…Here, three distinct killer whale assemblies or ecotypes have been described: Residents specialize on fish, live mainly in coastal waters and usually travel in large stable social units of closely related animals Ivkovich et al, 2010); Transients or Bigg's killer whales hunt primarily marine mammals and travel in smaller, more fluid social groups (Baird & Dill, 1996;Ford et al, 1998), and Offshores appear to specialize on sharks in their diet (Ford et al, 2011a) and typically occur in large groups (50+) with an unknown social structure. As the name indicates these whales are usually encountered further away from shore.…”

“…Resident killer whales live in stable matrilineal units that may group together, forming subpods and pods Ivkovich et al, 2010). Different pods produce distinct repertoires comprising a mix of unique and shared stereotyped call types, often referred to as a dialect.…”

Abundance estimates of killer whales at ­subantarctic Marion Island

“…The natural characteristics used to identify killer whales have proven to be long-lasting, allowing individuals to be recognized for years in long-term studies (e.g. Bigg et al 1987, Bigg et al 1990, Baird & Whitehead 2000, Parsons et al 2009, Ivkovich et al 2010). This makes killer whales conducive to MR analysis following rigorous photographic surveying and we therefore considered mark loss in this study as being negligible.…”