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Trends in annual and seasonal survival of Pink‐footed Geese Anser brachyrhynchus
Author(s) -
Madsen Jesper,
Frederiksen Morten,
Ganter Barbara
Publication year - 2002
Publication title -
ibis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.933
H-Index - 80
eISSN - 1474-919X
pISSN - 0019-1019
DOI - 10.1046/j.1474-919x.2002.00045.x
Subject(s) - annual cycle , seasonality , biology , population , demography , mark and recapture , relative survival , seasonal breeder , geography , ecology , cancer registry , sociology
Adult Pink‐footed Geese Anser brachyrhynchus from the Svalbard breeding population were neck‐banded and resighted in staging and wintering areas outside the breeding season 1990–1999. We estimated annual and seasonal survival using capture–recapture statistical models. Mean annual survival was 0.829, declining over the study period from 0.90 to 0.79. The annual cycle was partitioned into three periods: summer (1 April–30 September), including both spring and autumn migration, autumn (1 October–31 December), including most shooting, and winter (1 January–31 March). The parsimonious model selected to describe seasonal survival included a declining trend in summer survival, constant autumn and winter survival with lower survival in the severe winter of 1996, and an additive effect of sex on summer and winter survival. Monthly survival was highest during winter. Decreasing summer survival was the main contributor to the overall decline in annual survival, and was attributed mainly to increasing natural mortality on the breeding grounds. Mean annual survival based on the seasonal survival probabilities was 0.835 for females and 0.805 for males. The effect of sex was most pronounced during summer and remains to be explained.