A comparison of Northeast Atlantic killer whale (Orcinus orca) stereotyped call repertoires

Abstract

Killer whale call repertoires can provide information on social connections among groups and populations. Killer whales in Iceland and Norway exhibit similar ecology and behavior, are genetically related, and are presumed to have been in contact before the collapse of the Atlanto-Scandian herring stock in the 1960s. However, photo-identification suggests no recent movements between Iceland and Norway but regular movement between Iceland and Shetland. Acoustic recordings collected between 2005 and 2016 in Iceland, Norway, and Shetland were used to undertake a comprehensive comparison of call repertoires of Northeast Atlantic killer whales. Measurements of time and frequency parameters of calls from Iceland (n = 4,037) and Norway (n = 1,715) largely overlapped in distribution, and a discriminant function analysis had low correct classification rate. No call type matches were confirmed between Iceland and Norway or Shetland and Norway. Three call types matched between Iceland and Shetland. Therefore, this study suggests overall similarities in time and frequency parameters but some divergence in call type repertoires. This argues against presumed past contact between Icelandic and Norwegian killer whales and suggests that they may not have been one completely mixed population.

Killer Whale (Orcinus orca) Pulsed Calls in the Eastern Canadian Arctic

“…Killer whales produce a variety of acoustic calls, including echolocation clicks, single-toned whistles, and discrete pulsed calls (Ford and Fisher, 1986;Simonis et al, 2012). Pulsed calls are the most common in killer whale vocal repertoires (Ford, 1984(Ford, , 1989Deecke et al, 2011;Selbmann et al, 2021). They have been described as acoustically complex, stereotyped, and include rapidly repeating broadband pulses with frequency modulated fundamental frequencies and strong harmonic structures (Wellard et al, 2015;Rice et al, 2017).…”

“…Killer whales in the Northeast Pacific have been studied for decades, and vocal repertoires have been described for most resident and transient ecotypes (Ford, 1984;Sharpe et al, 2019;Madrigal et al, 2021;Selbmann et al, 2021). Vocal repertoires of Northeast Atlantic killer whales have only been described more recently (Deecke et al, 2011;Foote et al, 2014;Selbmann et al, 2021).…”

“…Killer whales in the Northeast Pacific have been studied for decades, and vocal repertoires have been described for most resident and transient ecotypes (Ford, 1984;Sharpe et al, 2019;Madrigal et al, 2021;Selbmann et al, 2021). Vocal repertoires of Northeast Atlantic killer whales have only been described more recently (Deecke et al, 2011;Foote et al, 2014;Selbmann et al, 2021). For example, Norwegian killer whale pulsed calls exhibit strong harmonic banding, with fundamental frequencies that range between 0.04 and 4.8 kHz with durations between 0.11 and 2.2 s (Strager, 1995).…”

Vocal Behaviour of Killer Whales in the Eastern Canadian Arctic and the Role of Calls in Predator-prey Interactions

“…Pulsed calls are proposed to function in general contact, maintaining group cohesion, or to aid in individual recognition among relatives (Ford, 1984(Ford, , 1989Miller, 2002). Pulsed calls are often highly stereotyped, allowing them to be classified into distinct categories and compared across groups (Ford, 1989;Selbmann et al, 2021). In the North Pacific, where killer whales have been most extensively studied, Ford (1984) described the presence of group/pod-specific dialects of pulsed calls.…”

“…In the North Pacific, where killer whales have been most extensively studied, Ford (1984) described the presence of group/pod-specific dialects of pulsed calls. It was later determined that groupspecific dialects and the broader vocal traditions of clans provide measures of maternal relatedness and, therefore, information about the amount of movement of individuals among sympatric or geographically close groups (Ford, 1991;Strager, 1995;Yurk, 2005;Deecke et al, 2010;Selbmann et al, 2021). Thus, studying killer whale vocalizations can provide information on their behaviour, interactions with both con-and heterospecifics, and group structure.…”