Breeding biology of the Red-throated Loon Gavia stellata on the Holmöarna archipelago, Northern Sweden

  • Christer Olsson
  • Jan Pettersson
  • Frank Johansson Department of Ecology and Genetics, Uppsala University
Keywords: Baltic Sea, breeding success, Common Crane, Grus grus, predation, Red-throated Diver

Abstract

The aim of this study was to estimate number of breeding pairs, breeding success, and distance to fishing areas in a population of the Red-throated Loon Gavia stellata on two of the main islands in the Holmöarna Archipelago in the northern part of the Baltic Sea, Sweden. Potential breeding waters were surveyed during seven years, 2010–2015 and 2019. Red-throated Loons appeared in 43 of the 135 lakes of sufficient size on the islands, and the population was estimated to 25–35 pairs, or about 2% of the Swedish population. The mean size of lakes with breeding pairs was 1.6 ha, and these lakes had an average of 82% water surface without vegetation (18% vegetation cover). The mean breeding success was low, 0.30 chicks per pair and year, and at least during one year, chicks were produced in only 20 (47%) of the surveyed lakes. The average distance between the nesting waters and the fishing areas for 17 studied pairs was 1.8 km. We discuss the characteristics of suitable nesting waters as well as the factors contributing to the low reproduction.

Published
2021-01-26
How to Cite
Olsson, C., Pettersson, J., & Johansson, F. (2021). Breeding biology of the Red-throated Loon Gavia stellata on the Holmöarna archipelago, Northern Sweden. Ornis Svecica, 31, 1–18. https://doi.org/10.34080/os.v31.22276
Section
Research Papers