Table of Contents
ISRN Zoology
Volume 2011, Article ID 929460, 8 pages
Research Article

Effects of Variable Food Supply on the Body Condition of Breeding Tawny Owls Strix aluco in Southern Finland

Luontotutkimus Solonen Oy, Neitsytsaarentie 7b B 147, 00960 Helsinki, Finland

Received 20 January 2011; Accepted 15 March 2011

Academic Editor: U. Shanas

Copyright © 2011 Tapio Solonen. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Body condition of boreal species of vole-eaters seems to vary in accordance with fluctuating vole populations. Tawny owls Strix aluco of temperate origin were studied to reveal if they show a similar pattern during nestling period near the northern limit of the species' range. The body condition of tawny owls was not considerably affected by the annual fluctuations of small voles indicated by regional vole indices and local prey samples. There were some significant relationships with some alternative prey but the variation in the body condition of owls was largely explained by the bird's age, time of the season, and stage of the nestling period. Old birds that bred earlier in the season were in better condition than young ones that bred later. Due to alternative prey, the body condition seemed to be relatively resistant to the effects of variable foraging conditions as expected for a generalist species of southern origin.