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Dusky dolphins influence prey accessibility for seabirds in Admiralty Bay, New Zealand

Citation

Vaughn, RL and Wursig, B and Shelton, DS and Timm, LL and Watson, LA, Dusky dolphins influence prey accessibility for seabirds in Admiralty Bay, New Zealand, Journal of Mammalogy, 89, (4) pp. 1051-1058. ISSN 0022-2372 (2008) [Refereed Article]

Copyright Statement

Copyright 2008 American Society of Mammalogists

DOI: doi:10.1644/07-MAMM-A-145.1

Abstract

Although seabirds frequently aggregate with feeding delphinids, the benefits to seabirds of feeding with dolphins have been rarely reported. We examined how dusky dolphins (Lagenorhynchus obscurus) influenced prey accessibility for seabirds in Admiralty Bay, New Zealand. Interactions of dusky dolphins and seabirds were characterized during 335 feeding bouts of dusky dolphins (52 video-recorded underwater). Dolphins increased prey accessibility for seabirds because they swam under the bottom half of prey balls for 59% of passes that were within 2 m of the prey ball. During feeding bouts by dolphins, 51% of prey balls ascended, whereas only 13% descended. Dolphins also influenced prey mobility; only 24% of stationary feeding bouts became mobile after dolphins began feeding, and 17% subsequently became stationary again. Significantly more Australasian gannets (Morus serrator) were near mobile than stationary prey balls after feeding, but not during feeding bouts. This suggests that feeding gannets increase mobility of prey balls, but that feeding dolphins counteract this effect. Seabirds also used dusky dolphins to locate prey. Numbers of gannets, shearwaters (Puffinus), and gulls (Larus) increased during the first 2 min of dolphin feeding, even when other seabirds were not present. Gannets fed with dolphins for 40% of gannet feeding observations and shearwaters fed with dolphins for 24% of shearwater feeding observations.

Item Details

Item Type:Refereed Article
Keywords:dusky dolphin, feeding behavior, foraging ecology, gannet, gull, Lagenorhynchus obscurus, mixed species aggregations, Morus serrator, seabird, shearwater
Research Division:Biological Sciences
Research Group:Ecology
Research Field:Marine and Estuarine Ecology (incl. Marine Ichthyology)
Objective Division:Environment
Objective Group:Flora, Fauna and Biodiversity
Objective Field:Marine Flora, Fauna and Biodiversity
Author:Watson, LA (Dr Leslie Watson)
ID Code:121225
Year Published:2008
Web of Science® Times Cited:24
Deposited By:Directorate
Deposited On:2017-09-18
Last Modified:2018-05-21
Downloads:0

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