Call repertoire and inferred ecotype presence of killer whales ( Orcinus orca ) recorded in the southeastern Chukchi Sea

• Main Authors: Madrigal, Brijonnay C., Crance, Jessica L., Berchok, Catherine L., Stimpert, Alison K.
• Format: Text
• Language: unknown
• Published: DigitalCommons@University of Nebraska - Lincoln 2021
• Subjects: Arctic; Chukchi Sea; Point Hope; Chukchi; Killer Whale; Orca; Orcinus orca; Alaska; Killer whale
• Online Access: https://digitalcommons.unl.edu/usdeptcommercepub/623; https://digitalcommons.unl.edu/context/usdeptcommercepub/article/1628/viewcontent/Madrigal_JASA_2021_Call_repertoire.pdf

Killer whales occur in the Arctic but few data exist regarding the ecotypes present. The calling behavior differs among ecotypes, which can be distinguished based on pulsed call type, call rate, and bandwidth. In this study, a passive acoustic recorder was deployed 75 km off Point Hope, Alaska, in the southeastern Chukchi Sea to identify which ecotypes were present. A total of 1323 killer whale pulsed calls were detected on 38 of 276 days during the summers (June–August) of 2013–2015. The majority of calls (n = 804, 61%) were recorded in 2013 with the most calls recorded in July (76% of total calls). The calls were manually grouped into six categories: multipart, downsweep, upsweep, modulated, single modulation, and flat. Most detections were flat (n = 485, 37%) or multipart calls (n = 479, 36%), which contained both high and low frequency components. Call comparisons with those reported in the published literature showed similarities with other transient populations in fundamental frequency contour point distribution and median frequency. This study provides the first comprehensive catalog of transient killer whale calls in this region as well as reports on previously undescribed calls.