High-Frequency Modulated Signals Recorded Off the Antarctic Peninsula Area: Are Killer Whales Emitting Them?
High-frequency modulated signals with a stereotyped down-swept contour were recorded in the northwestern Antarctic Peninsula using an autonomous recorder and a towed hydrophone array. Signals have a mean start frequency at 21.6 kHz, end frequency at 15.7 kHz, −10 dB bandwidth of 5.9 kHz, and duration of 65.2 ms. Bouts of signals were generally recorded with a median inter-signal interval of 2.1 s. HFM signals partially modulated in the non-ultrasonic range similar to the ones described in this paper have already been reported for killer whales in the North Pacific, Western South Atlantic and Western Australian coast. The HFM signals were recorded in the presence of other odontocete sounds such as whistles, echolocation clicks and burst-pulsed sounds. The similarities of these sounds with vocalizations described for killer whales in the Western Australian coast lead us to strongly believe that the described HFM signals were produced by Antarctic killer whales. This paper described for the first time HFM signals in Antarctica and discussed evidence suggesting that Antarctic type A killer whales are the most probable candidates to produce such signals. However, a visual confirmation is still needed and the function of the HFM signals remains unknown.
KeywordsHigh-frequency modulated signals Antarctic killer whale morphotype Orcinus orca
The authors thank Ana Širović, Sean M. Wiggins, Ryan Griswold, and Joshua Jones for instrument development, preparation, and fieldwork. We also thank Marta Hevia, the Prefectura Naval Argentina, and the officers and crew of the vessel SB-15 “Tango” for their assistance with fieldwork. Funding for this project was provided by the University of California San Diego Academic Senate, the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Fundacion Cethus, and Whale and Dolphin Conservation.
- 2.Pitman, R.L., Ensor, P.: Three forms of killer whales (Orcinus orca) in Antarctic waters. J. Cetacean Res. Manag. 5(2), 131–139 (2003)Google Scholar
- 10.Jefferson, T.A., Webber, M.A., Pitman, R.L.: Marine Mammals of the World: A Comprehensive Guide to their Identification. Elsevier, London (2008)Google Scholar
- 11.Ford, J.K.B., Fisher, H.D.: Killer whale (Orcinus orca) dialects as an indicator of stocks in British Columbia. Rep. Int. Whal. Comm. 32, 671–679 (1982)Google Scholar
- 22.Andriolo, A., Reis, S.S., Amorim, T.O., Sucunza, F., de Castro, F.R., Maia, Y.G., Zerbini, A.N., Bortolotto, G.A., Dalla Rosa, L.: Killer whale (Orcinus orca) whistles from the western South Atlantic Ocean include high frequency signals. J. Acoust. Soc. Am. 138(3), 1696–1701 (2015)CrossRefGoogle Scholar
- 29.Morin, P.A., Parsons, K.M., Archer, F.I., Avila-Arcos, M.C., Barrett-Lennard, L.G., Dalla Rosa, L., Duchene, S., Durban, J.W., Ellis, G.M., Ferguson, S.H., Ford, J.K., Ford, M.J., Garilao, C., Gilbert, M.T.P., Kaschner, K., Matkin, C.O., Petersen, S.D., Robertson, K.M., Visser, I.N., Wade, P.R., Ho, S.Y.W., Foote, A.D.: Geographic and temporal dynamics of a global radiation and diversification in the killer whale. Mol. Ecol. 24, 3964–3979 (2015)CrossRefGoogle Scholar
- 30.Awbrey, F.T., Thomas, J.A., Evans, W.E., Leatherwood, S.J.: Ross sea killer whale vocalizations: preliminary description and comparison with those of some northern hemisphere killer whales. Rep. Int. Whal. Comm. 32, 667–670 (1982)Google Scholar
- 33.Wiggins, S.M., Hildebrand, J.A.: High-frequency acoustic recording package (HARP) for broad-band, long-term marine mammal monitoring. In: International Symposium on Underwater Technology 2007 and International Workshop on Scientific Use of Submarine Cables & Related Technologies 2007, pp. 551–557. Institute of Electrical and Electronics Engineers, Tokyo, Japan (2007)Google Scholar
- 34.Kasamatsu, F., Hembree, D., Joyce, G., Tsunoda, L., Rowlett, R., Nakano, T.: Distribution of cetacean sightings in the Antarctic: results from the IWC/IDCR Southern Hemisphere minke whale assessment cruises 1978/79–1983/84. Rep. Int. Whal. Comm. 38, 449–487 (1988)Google Scholar
- 36.Vester, H: Vocal repertoires of two matrilineal social whale species: long-finned Pilot whales (Globicephala melas) & Killer whales (Orcinus orca) in northern Norway. Ph.D. Dissertation Georg-August University of Göttingen (2017)Google Scholar