RapportAnnual survival of Swedish Lesser White-fronted Geese

Annual survival of Swedish Lesser White-fronted Geese
Omslag Annual survival of Swedish Lesser White-fronted Geese

A dataset of 663 individually marked Lesser White-fronted Geese and 8000 resightings was used to analyse annual survival rates in the Swedish breeding population. One period covered 1984-1999, when juvenile Lesser White-fronted Geese were released with Barnacle Geese serving as foster parent; the second 2010-2017, when fledglings were released in flocks without parental care. In both periods, also 2nd year birds (yearlings) were released, either as independent flocks (period 1) or in flocks together with fledglings (period 2). Survival analyses were performed using program MARK. A year was defined as the period from 1 May to 1 May to account for the distribution of resightings within the year. Calculations were done for 1984-2003 (period 1) and 2012-2017 (period 2). Resighting probability was high and at present, most geese alive are reported at some stage during the year. The results of the analyses show differences according to sex (mostly small), age and age when released. In some of these groups, results are different for the first and second part of the release program.

Sovon Vogelonderzoek Nederland