Set-back distances to protect nesting and roosting seabirds off Vancouver Island from boat disturbance

Abstract

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.