Geographical and temporal trends in echolocation clicking activity can lead to insights into the foraging and migratory behaviors of pelagic dolphins. Using autonomous acoustic recording packages, the geographical, diel, and seasonal patterns of Risso’s dolphin (Grampus griseus) echolocation click activity are described for six locations in the Southern California Bight between 2005 and 2007. Risso’s dolphin echolocation click bouts are identified based on their unique spectral characteristics. Click bouts were identified on 739 of 1959 recording days at all 6 sites, with the majority occurring at nearshore sites. A significant diel pattern is evident in which both hourly occurrences of click bouts and click rates are higher at night than during the day. At all nearshore sites, Risso’s dolphin clicks were identified year-round, with the highest daily occurrence at the southern end of Santa Catalina Island. Seasonal and interannual variabilities in occurrence were high across sites with peak occurrence in autumn of most years at most sites. These results suggest that Risso’s dolphins forage at night and that the southern end of Santa Catalina Island represents an important habitat for Risso’s dolphins throughout the year.
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January 2010
January 05 2010
Spatial and temporal patterns of Risso’s dolphin echolocation in the Southern California Bight
Melissa S. Soldevilla;
Melissa S. Soldevilla
a)
Scripps Institution of Oceanography,
University of California, San Diego
, 9500 Gilman Drive 0205, La Jolla, California 92093
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Sean M. Wiggins;
Sean M. Wiggins
Scripps Institution of Oceanography,
University of California, San Diego
, 9500 Gilman Drive 0205, La Jolla, California 92093
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John A. Hildebrand
John A. Hildebrand
Scripps Institution of Oceanography,
University of California, San Diego
, 9500 Gilman Drive 0205, La Jolla, California 92093
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a)
Author to whom correspondence should be addressed. Electronic mail: melissa.soldevilla@duke.edu. Present address: 135 Duke Marine Lab Road, Beaufort, NC 28516.
J. Acoust. Soc. Am. 127, 124–132 (2010)
Article history
Received:
February 17 2009
Accepted:
October 06 2009
Citation
Melissa S. Soldevilla, Sean M. Wiggins, John A. Hildebrand; Spatial and temporal patterns of Risso’s dolphin echolocation in the Southern California Bight. J. Acoust. Soc. Am. 1 January 2010; 127 (1): 124–132. https://doi.org/10.1121/1.3257586
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