Set-back Distances to protect nesting and roosting seabirds off Vancouver Island from boat disturbance
Trudy Chatwin’s Master’s theses from Royal Roads University.
In order to set guidelines that promote responsible wildlife viewing, I quantified the effects of boat-based disturbance to seabirds off Vancouver Island. Field trials recorded the approach distance at which roosting and nesting birds responded to either a motor boat or a kayak. Probability of agitation response was used to evaluate disturbance. At a distance of 40 m nesting Double-crested Cormorants, Pelagic Cormorants, Glaucous-winged Gulls, Pigeon Guillemots and Black Oystercatchers had less than an 8% chance of being agitated with either a kayak or motorboat approach. Roosting birds had longer response distances. Harlequin Ducks were particularly sensitive with a 25% probability of agitation at distances less than 50 m. Agitation distances were reduced by habituation to boat traffic. A set-back guideline of 50 m would protect most nest and roost sites in the study area while allowing viewers to appreciate seabirds. Some sensitive sites would require 70 m set-backs.
See full PDF:Chatwin, Trudy
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