Volume 43, No. 2

Search by author or title:

Testing the effectiveness of automated acoustic sensors for monitoring vocal activity of Marbled Murrelets Brachyramphus marmoratus


1Department of Biology, University of Victoria, Victoria, BC V8W 3N5, Canada (
2Current address: 2876 Philip Street, Duncan, BC V9L 2A7, Canada
3US Geological Survey, Alaska Science Center, Anchorage, AK 99503, USA


CRAGG, J.L., BURGER, A.E. & PIATT, J.F. 2015. Testing the effectiveness of automated acoustic sensors for monitoring vocal activity of Marbled Murrelets Brachyramphus marmoratus. Marine Ornithology 43: 151 - 160

Received 26 June 2014; accepted 17 April 2015

Date Published: 2015/10/15
Date Online: 2017/02/28
Key words: Marbled Murrelet, Brachyramphus marmoratus, automated acoustic recording, population monitoring, habitat use, vocalization, Kodiak Island 


Cryptic nest sites and secretive breeding behavior make population estimates and monitoring of Marbled Murrelets Brachyramphus marmoratus difficult and expensive. Standard audio-visual and radar protocols have been refined but require intensive field time by trained personnel. We examined the detection range of automated sound recorders (Song Meters; Wildlife Acoustics Inc.) and the reliability of automated recognition models (“recognizers”) for identifying and quantifying Marbled Murrelet vocalizations during the 2011 and 2012 breeding seasons at Kodiak Island, Alaska. The detection range of murrelet calls by Song Meters was estimated to be 60 m. Recognizers detected 20 632 murrelet calls (keer and keheer) from a sample of 268 h of recordings, yielding 5 870 call series, which compared favorably with human scanning of spectrograms (on average detecting 95% of the number of call series identified by a human observer, but not necessarily the same call series). The false-negative rate (percentage of murrelet call series that the recognizers failed to detect) was 32%, mainly involving weak calls and short call series. False-positives (other sounds included by recognizers as murrelet calls) were primarily due to complex songs of other bird species, wind and rain. False-positives were lower in forest nesting habitat (48%) and highest in shrubby vegetation where calls of other birds were common (97%–99%). Acoustic recorders tracked spatial and seasonal trends in vocal activity, with higher call detections in high-quality forested habitat and during late July/early August. Automated acoustic monitoring of Marbled Murrelet calls could provide cost-effective, valuable information for assessing habitat use and temporal and spatial trends in nesting activity; reliability is dependent on careful placement of sensors to minimize false-positives and on prudent application of digital recognizers with visual checking of spectrograms. 


Bigger, D., Peery, Z.M., Chinnici, S. & Courtney, S.P. 2006. Efficacy of audiovisual and radar surveys for studying Marbled Murrelets in inland habitats. Journal of Wildlife Management 70: 505–516.

Borker, A.L., McKown, M.L., ACKERMAN, J.T., EAGLES-SMITH, C.A., Tershy, B.R. & Croll, D.A. 2014. Vocal activity as a low cost and scalable index of seabird colony size. Conservation Biology 28: 1100–1108.

Burger, A.E. 1997. Behavior and numbers of Marbled Murrelets measured with radar. Journal of Field Ornithology 68: 208–223. 

Burger, A.E. 2001. Using radar to estimate populations and assess habitat associations of Marbled Murrelets. Journal of Wildlife Management 65: 696–715.

Burger, A.E. 2004. Standard methods for identifying and ranking nesting habitat of Marbled Murrelets in British Columbia using air photo interpretation and low-level aerial surveys. Victoria, BC: Ministry of Water, Land and Air Protection, Biodiversity Branch. 

Burger, A.E. & Bahn, V. 2004. Inland habitat associations of Marbled Murrelets on southwest Vancouver Island, British Columbia. Journal of Field Ornithology 75: 53–66.

Buxton, R.T. & Jones, I.L. 2012. Measuring nocturnal seabird activity and status using acoustic recording devices: applications for island restoration. Journal of Field Ornithology 83: 47–60.

Buxton, R.T., Major H.L., Jones I.L. & Williams, J.C. 2013. Examining patterns in nocturnal seabird activity and recovery across the Western Aleutian Islands, Alaska, using automated acoustic recording. Auk 130: 331–341.

Canadian Marbled Murrelet Recovery Team (CMMRT). 2003. Marbled murrelet conservation assessment 2003, Part B: Marbled Murrelet recovery team advisory document on conservation and management. Canadian Marbled Murrelet Recovery Team Working Document No. 1. Delta, BC: Canadian Wildlife Service, Pacific and Yukon Region. [Available online from:; accessed 6 July 2015.]

Cooper, B.A. & Blaha, R.T. 2002. Comparisons of radar and audio-visual counts of Marbled Murrelets during inland forest surveys. Wildlife Society Bulletin 30: 1182–1194.

Cooper, B.A., Raphael, M.G. & Evans Mack, D. 2001. Radar-based monitoring of Marbled Murrelets. Condor 103: 219–229.

Cragg, J.L. 2013. Brachyramphus murrelets at high latitude: behavioural patterns and new methods for population monitoring. M.Sc. thesis. Victoria, BC: University of Victoria.

Dechesne, S.B.C. 1998. Vocalizations of the Marbled Murrelet (Brachyramphus marmoratus): vocal repertoire and individuality. M.Sc. thesis. Victoria, BC: University of Victoria. 

Evans Mack, D., Ritchie, W.P., Nelson, S.K., Kuo-Harrison, E., Harrison, P. & Hamer, T.E. 2003. Methods for surveying Marbled Murrelet in forests: a revised protocol for land management and research. Technical Publication No. 2. Portland, OR: Pacific Seabird Group. 

Jodice, P.G.R. & Collopy, M.W. 2000. Activity patterns of Marbled Murrelets in Douglas-fir old-growth forests in the Oregon Coast Range. Condor 102: 275–285.

Jodice, P.G.R., Garman, S.L. & Collopy, M.W. 2001. Using resampling to assess reliability of audio-visual survey strategies for Marbled Murrelets at inland forest sites. Waterbirds 24: 331–344.

McKown, M.W., Lukac, M., Borker, A., Tershy, B. & Croll, D. 2012. A wireless acoustic sensor network for monitoring wildlife in remote locations. Journal of the Acoustical Society of America 132: 2036.

McShane, C., Hamer, T., Carter, H., Swartzman, G., Friesen, V., Ainley, D., Tressler, R., Nelson, K., Burger, A., Spear, L., Monagen, T., Martin, R., Henkel, L., Prindle, K., Strong, C. & Keany, J. 2004. Evaluation report for the 5-year status review of the Marbled Murrelet in Washington, Oregon, and California. Portland, OR: US Fish and Wildlife Service, Region 1. 

Meyer, C.B., Miller, S.L. & Ralph, C.J. 2004. Stand-scale habitat associations across a large geographic region of an old-growth specialist, the Marbled Murrelet. Wilson Bulletin 116: 197–210. 

Miller, S.L., Raphael, M.G., Falxa, G.A., Strong, C., Baldwin, J., Bloxton, T., Galleher, B.M., Lance, M., Lynch, D., Pearson, S.F., Ralph, C.J. & Young, R.D. 2012. Recent population decline of the Marbled Murrelet in the Pacific Northwest. Condor 114: 771–781. 

Nelson, K. 1997. Marbled Murrelet (Brachyramphus marmoratus). In: Poole A. & Gill G. (Eds.) Birds of North America, No. 276. Washington, DC: Academy of Natural Sciences and American Ornithologists' Union. 

Oppel, S., Hervias, S., Oliveira, N., Pipa, T., Silva, C., Geraldes, P., Goh, M., Immler, E. & McKown, M. 2014. Estimating population size of a nocturnal burrow-nesting seabird using acoustic monitoring and habitat mapping. Nature Conservation 7: 1–13.

Piatt, J.F., Kuletz, K.J., Burger, A.E., Hatch, S.A., Friesen, V.L., Birt, T.P., Arimitsu, M.L., Drew, G.S., Harding, A.M.A. & Bixler, K.S. 2007. Status review of the Marbled Murrelet (Brachyramphus marmoratus)

in Alaska and British Columbia. US Geological Survey

Open-File Report 2006-1387. Reston, VA: US Geological Survey.

Ralph, C.J., Hunt, G.L. Jr., Raphael, M.G. & Piatt, J.F. (Eds.). 1995. Ecology and conservation of the Marbled Murrelet in North America. General Technical Report PSW-GTR-152. Albany, CA: Pacific Southwest Research Station, Forest Service, US Department of Agriculture.

Raphael, M.G. 2006. Conservation of the Marbled Murrelet under the Northwest Forest Plan. Conservation Biology 20: 297–305.

Rodway, M.S., Regehr, H.M. & Savard, J.-P.L. 1993. Activity patterns of Marbled Murrelets in old-growth forest in the Queen Charlotte Islands, British Columbia. Condor 95: 831–848.

Stauffer, H.B., Ralph, C.J. & Miller, S.L. 2004. Ranking habitat for Marbled Murrelets: new conservation approach for species with uncertain detection. Ecological Applications 14: 1374–1383.

Venier, L.A., Holmes, S.B., Holborn, G.W., McIlwrick, K.A. & Brown, G. 2012. Evaluation of an automated recording device for monitoring forest birds. Wildlife Society Bulletin 36: 30–39.

Wildlife Acoustics. 2011. Song Scope Bioacoustics software version 4.0 documentation. Concord, MA: Wildlife Acoustics Inc.

Wildlife Acoustics. 2013. Overview of the Song Stream Remote Access Module. Concord, MA: Wildlife Acoustics Inc. 

Wimmer, J., Towsey, M., Roe, P. & Williamson, I. 2013. Sampling environmental acoustic recordings to determine bird species richness. Ecological Applications 23: 1419–1428.

Search by author or title:

Browse previous volumes: