Sequential Habitat Use by Two Resident Killer Whale (<I>Orcinus orca</I>) Clans in Resurrection Bay, Alaska, as Determined by Remote Acoustic Monitoring

Abstract

Killer whales (Orcinus orca) are sighted regularly in coastal Alaska during the summer, but little is known about their movements through the area during the winter when weather and light limit the use of boat-based surveys. Acoustic monitoring provides a practical alternative because each extended resident killer whale family group or pod has a unique dialect that can be discerned by differences in their repertoires of stereotyped calls. The repertoires of resident killer whale pods in the northern Gulf of Alaska were updated from earlier studies, and the results used to determine the identity of pods that were recorded on remote hydrophones in Resurrection Bay, Alaska, in the fall, winter, and spring of 1999 to 2004. In total, seven pods of resident killer whales were identified acoustically, comprising four related pods from AB clan and three from AD clan. The frequencies of occurrence of the clans differed between the November to March recording period when AB clan occupied the area, and the April-May period when AD clan was predominant. The sequential use of this habitat during periods of relative prey scarcity has the effect of limiting intergroup resource competition and is consistent with earlier findings that demonstrated divergent resource specialization by sympatric killer whale populations.

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

“…N Pacific vs N Atlantic) and finescale analysis of similarity of different components of repertoires are promising directions for future research. Thomsen et al, 2002Deecke et al, 2000Miller, Bain 2000Miller 2002, 2006Miller et al, 2004Foote et al, 2004Foote et al, 2006Nousek et al, 2006Riesch et al, 2006Miller et al2007Riesch et al, 2008Weiß et al, 2006Rehn et al, 2007Foote and Nystuen 2008Holt et al, 2008Wieland et al, 2010Yurk et al, 2010Grebner et al, 2011 The first syllable may vary in frequency from <2 kHz ("l", low) to 2-4 kHz ("m", medium) and >4 kHz ("h", high). "h" and "l" variants may occur simultaneously, yielding two-voiced sounds ("I43 hlb" on this figure) The second syllable appears in at least four forms ("a"-"c") that occur in various combinations with variations of the first syllable.…”

Spatial and temporal occurrence of killer whale ecotypes off the outer coast of Washington State, USA

“…Seasonal segregation of resident clans was observed in southeastern Alaska during periods of reduced prey availability (Yurk et al 2010). Since resident communities off Washington share a preference for Chinook salmon, it is possible that these communities could also show seasonal segregation during times of reduced prey availability.…”

Passive acoustic monitoring off Vancouver Island reveals extensive use by at-risk Resident killer whale (Orcinus orca) populations

“…Several cetacean species exhibit temporal variability in habitat use to avoid interspecific competition for limited resources (Perrin et al 1985, Gowans & Whitehead 1995, Bearzi 2005, Azzellino et al 2008, Simon et al 2010, Nichol et al 2013. Sequential habitat use has also been reported for sympatric populations of Resident killer whales in Alaska (Yurk et al 2010). These observations support the idea that the 2 Resident populations in our study could be temporally partitioning their use of the Swiftsure Bank region to avoid food com-petition; however, other factors, such as the littleunderstood social dynamics between the 2 populations, could also be playing a role.…”

“…The open waters of Swiftsure Bank are generally not conducive to conventional study techniques using small boats due to remoteness and poor weather and sea conditions. However, autonomous acoustic instruments can be deployed at remote locations and record over extended periods to investigate killer whale presence across seasons and years (Yurk et al 2010) while providing the additional benefits of being non-invasive (Nystuen et al 2010) and monitoring regardless of the weather and time of day (Akamatsu et al 2008, Giorli et al 2015.…”