Effects of motorised boat passes on the time budgets of New Zealand dabchick, Poliocephalus rufopectus

Abstract

New Zealand dabchicks, Poliocephalus rufopectus, are small grebes restricted to the North Island of New Zealand; with a total population of only ~1200–1500 birds, they are classed as endangered. We conducted experiments to examine the effects of boat passes of different speeds and frequencies on the time budgets of the New Zealand dabchick. We also examined whether New Zealand dabchicks became habituated to boat passes. We found that a single boat pass caused a significant short-term change in New Zealand dabchick behaviour compared with pre–boat pass patterns. This change in behaviour was more pronounced when the frequency of boat passes was higher, and may impose energetic constraints on New Zealand dabchicks. Differences between behaviour before and after the boat pass were no longer evident 15 minutes after the boat pass. We found no significant effects of boat speed (5 v. 10 knots) on the behaviour of New Zealand dabchicks. There was evidence of habituation to boat traffic in high-use recreational sites. Further studies are required to investigate the influence of other human activities and the influence that boat and wave wash have on the nesting and breeding success of the New Zealand dabchick.