Abstract

As many seaduck populations around the world have been reported to be in decline, there is an increasing demand for knowledge about intrinsic and extrinsic factors determining population dynamics of these species. In this study, we analyzed long-term dynamics of the summer population of Velvet Scoters (Melanitta fusca) breeding in the Aland archipelago in the Baltic Sea; in particular, we examined the influence of winter weather and density dependence on population change. The studied population exhibited substantial fluctuations but only a weak negative trend during the total period of 58 years (1949-2007), and no significant trend at all during the latter three decades of the study (1977-2007). We tested for density dependence and incorporated the winter North Atlantic Oscillation index into the model to test for effects of winter conditions. Our final model explained 56.3 % of the variance of population growth of the studied population. Delayed density dependence explained 29.7 %, pre-breeding climate 8.3 %, and post-breeding climate 18.3 % of the variance. That breeding success is density dependent in a delayed manner is in accordance with the apprehension that Velvet Scoters breed at the age of 2 years. We conclude that density dependence and winter conditions must be taken into consideration when discussing population changes in seaducks in general and the Velvet Scoter in particular.

Keywords

PBLR; NAO; TRIM; Seaducks; Baltic Sea

Published in

Journal of Ornithology
2013, Volume: 154, number: 3, pages: 837-847
Publisher: SPRINGER

SLU Authors

• Hartman, Göran

  • Department of Ecology, Swedish University of Agricultural Sciences
    

• Larsson, Karl

  • Department of Ecology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Ecology


Publication identifier

DOI: https://doi.org/10.1007/s10336-013-0950-7

Permanent link to this page (URI)

https://res.slu.se/id/publ/51554