The age of first breeding of cory’s shearwater on selvagem grande and problems of ring loss

Abstract

The Cory’s Shearwaters Calonectris diomedea borealis of Selvagem Grande (30°09’N, 15°52’W) breed for the first time between their 7th (exceptionally 6th) and 13th years with half the population breeding by their 9th year. The survival of the monel rings used in our study varies according to the colonies where the birds settle, but, because they were used on fledglings before their long period of immaturity at sea, no ring had fallen off because of wear, before the 13th year. Thus ring losses introduce no significant bias to our results. © 1986 Taylor & Francis Group, LLC.