Download or read book Impact of Seagull Presence on the Reproductive Success and Vigilance Behaviour of Common Terns in Kouchibouguac National Park New Brunswick written by Catherine Poussart and published by Halifax, N.S. : Parks Canada, Atlantic Region. This book was released on 1997 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since 1987, increasing numbers of gulls have nested next to a colony of common terns (Sterna hirundo) on Tern Island in Kouchibougouac National Park. This document describes a study conducted to estimate the risk of predation imposed on tern eggs and chicks by the presence of these gulls. The field studies compared the vigilance behaviour of terns nesting at the periphery of their colony to that of terns nesting in the centre of it, examining the hypothesis that vigilance would be greater at the periphery. Circular enclosures installed around groups of tern nests that contained eggs blocked the escape of tern chicks and allowed monitoring of hatching success, fledging success, and chick disappearance. Predation attempts by gulls outside of the enclosures were observed from a portable blind. All observations of vigilance behaviour took place at the egg stage and from a permanent blind.