Population Dynamics of Icelandic-Nesting Geese, 1960-1987

Publisher Website
Google Scholar
Abstract
The Icelandic- and Greenlandic-breeding Pink-footed Goose Anser brachyrhynchus population increased from 48,000 to 172,000 between 1960 and 1987. This growth can be explained by a survival rate of 89% based on observed breeding success. There is no evidence of density dependent factors operating on the population, and over 50% of the variance in an index of productivity was related to meteorological variables on the wintering grounds in spring prior to departure and on the nesting areas. The similar expansion in numbers of Greylag Geese A. anser nesting in Iceland and wintering in Britain [UK] from 30,000 in 1960 to 105,000 in 1987 showed survival rates of 91%, and over 70% of the variance in an index of breeding success could be explained by similar multiple regression models incorporating meteorological variables. Added evidence of the importance of meteorological variables, especially in Iceland, was provided by the close correlation between the annual productivity of the two species. With increasing population size, greater effort is required for adequate census, a problem compounded by the development of a wintering population in Ireland and a trend towards increasing numbers remaining in Iceland. The need for year-specific mortality estimates for use in full population models for both species is confirmed.