Skip to main content Accessibility help

Trialling an automated passive acoustic detector (T-POD) with Hector's dolphins (Cephalorhynchus hectori)

  • William Rayment (a1), Steve Dawson (a1) and Liz Slooten (a2)


Acoustic surveys can have several advantages over visual methods in surveys of cetaceans, although verification is required that novel techniques are effective. The T-POD is an autonomous acoustic data logger with inbuilt filters that can be set to match the click characteristics of the target species. We tested the performance of the T-POD for detecting Hector's dolphins at Flea Bay, Banks Peninsula, New Zealand. Simultaneous visual surveys were conducted from a hillside overlooking the bay, with distances between the T-POD and dolphins measured using a theodolite. Wideband sound recordings confirmed that T-POD detections were echolocation clicks made by Hector's dolphins. Detection probability and click train detection rate decreased with increasing distance, with no detections made beyond 500 m. By fitting detection functions to the probability of detection versus distance we showed that the T-POD effectively detected all dolphin groups within a radius of 198–239 m, depending on the click train categories utilized. The T-POD shows considerable promise as a tool for passive acoustic surveys of Hector's dolphins, with possible applications in studies of distribution, habitat use and echolocation behaviour.


Corresponding author

Correspondence should be addressed to: W. Rayment, Department of Marine Science, University of Otago, PO Box 56, Dunedin, New Zealand email:


Hide All
Akamatsu, T., Wang, D., Wang, K. and Wei, Z. (2001) Comparison between visual and passive acoustic detection of finless porpoises in the Yangtze River, China. Journal of the Acoustical Society of America 109, 17231727.
Au, W.W.L. (1993) The sonar of dolphins. New York: Springer-Verlag.
Au, W.W.L., Kastelein, R.A., Rippe, T. and Schooneman, N.M. (1999) Transmission beam pattern and echolocation signals of a harbor porpoise (Phocoena phocoena). Journal of the Acoustical Society of America 106, 36993705.
Barrett-Lennard, L.G., Ford, J.K.B. and Heise, K.A. (1996) The mixed blessing of echolocation, differences in sonar use by fish-eating mammal-eating killer whales. Animal Behaviour 51, 553565.
Buckland, S.T., Anderson, D.R., Burnham, K.P., Laake, J.L., Borchers, D.L. and Thomas, L. (2001) Introduction to distance sampling. New York: Oxford University Press Inc.
Carstensen, J., Henriksen, O.D. and Teilman, J. (2006) Impacts of offshore wind farm construction on harbour porpoises, acoustic monitoring of echolocation activity using porpoise detectors (T-PODs). Marine Ecology Progress Series 321, 295308.
Carlström, J. (2005) Diel variation in echolocation behaviour of wild harbour porpoises. Marine Mammal Science 21, 112.
Constantine, R., Brunton, D.H. and Dennis, T. (2004) Dolphin-watching tour boats change bottlenose dolphin (Tursiops truncatus) behaviour. Biological Conservation 117, 299307.
Cox, T.M., Read, A.J., Solow, A. and Tregenza, N. (2001) Will harbour porpoises (Phocoena phocoena) habituate to pingers? Journal of Cetacean Research and Management 3, 8186.
Dawson, S.M. (1991) Clicks and communication, the behavioural and social contexts of Hector's dolphin vocalisations. Ethology 88, 265276.
Dawson, S.M. and Thorpe, C.W. (1990) A quantitative analysis of the sounds of Hector's dolphin. Ethology 86, 131145.
Jefferson, T.A., Hung, S.K., Law, L., Torey, M. and Tregenza, N. (2002) Distribution and abundance of finless porpoises in Hong Kong and adjacent waters of China. The Raffles Bulletin of Zoology Supplement 10, 4355.
Jones, G.J. and Sayigh, L.S. (2002) Geographic variation in rates of vocal production of free-ranging bottlenose dolphins. Marine Mammal Science 18, 374393.
Koschinski, S., Culik, B.M., Henriksen, O.D., Tregenza, N., Ellis, G., Jansen, C. and Kathe, G. (2003) Behavioural reactions of free-ranging porpoises and seals to the noise of a simulated 2 MW windpower generator. Marine Ecology Progress Series 265, 263273.
Kyhn, L.A., Tougaard, J., Teilmann, J., Wahlberg, M., Jørgensen, P.B. and Bech, N.I. (2008) Harbour porpoise (Phocoena phocoena) static acoustic monitoring: laboratory detection thresholds of T-PODs are reflected in field sensitivity. Journal of the Marine Biological Association of the United Kingdom 88, 10851091.
Leaper, R., Chappell, O. and Gordon, J. (1992) The development of practical techniques for surveying sperm whale populations acoustically. Report of the International Whaling Commission 42, 549560.
McDonald, M.A. and Fox, C.G. (1999) Passive acoustic methods applied to fin whale population density estimation. Journal of the Acoustical Society of America 105, 26432651.
Mellinger, D.K., Stafford, K.M., Moore, S.E., Munger, L. and Fox, C.G. (2004) Detection of North Pacific right whale (Eubalaena japonica) calls in the Gulf of Alaska. Marine Mammal Science 20, 872879.
Mellinger, D.K., Nieukirk, S.L., Matsumoto, H., Heimlich, S.L., Dziak, R.P., Haxel, J., Fowler, M., Meinig, C. and Miller, H.V. (2007a) Seasonal occurrence of North Atlantic right whale (Eubalaena glacialis) vocalizations at two sites off the Scotian Shelf. Marine Mammal Science 23, 856867.
Mellinger, D.K., Stafford, K.M., Moore, S.E., Dziak, R.P. and Matsumoto, H. (2007b) An overview of fixed passive acoustic observation methods for cetaceans. Oceanography 20, 3645.
Philpott, E., Englund, A., Ingram, S. and Rogan, E. (2007) Using T-PODs to investigate the echolocation of coastal bottlenose dolphins. Journal of the Marine Biological Association of the United Kingdom 87, 1117.
Slooten, E. and Dawson, S.M. (1994) Hector's dolphin Cephalorhynchus hectori. In Ridgway, R.H. and Harrison, R. (eds) Handbook of marine mammals. Volume V (Delphinidae and Phocoenidae). New York: Academic Press, pp. 311333.
Thomsen, F., van Elk, N., Brock, V. and Piper, W. (2005) On the performance of automated porpoise click detectors in experiments with captive harbour porpoises (Phocoena phocoena) (L). Journal of the Acoustical Society of America 118, 3740.
Tougaard, J., Poulsen, L.R., Amundin, M., Laresen, F., Hansen, J.R. and Teilman, J. (2006) Detection function of T-PODs and estimation of porpoise densities. In Leeney, R.H. and Tregenza, N.J.C. (eds) Proceedings of the workshop Static Acoustic Monitoring of Cetaceans, 20th annual meeting of the European Cetacean Society, Gdynia, Poland, 2nd April 2006, pp. 713.
Van Parijs, S.M., Smith, J. and Corkeron, P.J. (2002) Using calls to estimate the abundance of inshore dolphins, a case study with Pacific humpback dolphins Sousa chinensis. Journal of Applied Ecology 39, 853864.
Verfuß, U.K., Honnef, C.G., Meding, A., Dahne, M., Mundry, R. and Benke, H. (2007) Geographical and seasonal variation of harbour porpoise (Phocoena phocoena) presence in the German Baltic Sea revealed by passive acoustic monitoring. Journal of the Marine Biological Association of the United Kingdom 87, 165176.
Villadsgaard, A., Wahlberg, M. and Tougaard, J. (2007) Echolocation signals of wild harbour porpoises, Phocoena phocoena. Journal of Experimental Biology 210, 5664.
Wang, K., Wang, D., Akamatsu, T., Li, S. and Xiao, J. (2005) A passive acoustic monitoring method applied to observation and group size estimation of finless porpoises. Journal of the Acoustical Society of America 118, 11801185.
Zar, J.H. (1999) Biostatistical analysis, 4th edition.Upper Saddle River, New Jersey: Prentice-Hall.


Related content

Powered by UNSILO

Trialling an automated passive acoustic detector (T-POD) with Hector's dolphins (Cephalorhynchus hectori)

  • William Rayment (a1), Steve Dawson (a1) and Liz Slooten (a2)


Altmetric attention score

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed.