Abstract
The breeding biology of the Tawny Owl Strix aluco was studied during 15 years in a 1,000 km2 area in south-western Sweden. The owls were breeding in c. 170 nest boxes, one in each of a potential territory. Occupancy rose from less than 20% in the first years to better than 50% in most of the later years. During the first years most nest boxes were relocated to sites within the territories that we considered to be of better quality. Absence of any increase in 48 high quality control territories indicates that the relocations were important for increasing population size. Nesting success was positively correlated with population density. This unexpected result could regrettably not be analyzed in relation to food abundance as we estimated food abundance by the number of prey found in nests. Bank vole, field vole and wood mice were the most predominant prey. All these three taxa had a peak in 2010 when owl density also peaked. The mean brood size was 2.3 young, similar to that in other European populations.
Highlights
There is a considerable interest of how reproductive success varies between years and over longer periods of time
Tawny Owls Strix aluco feed on different kinds of animal prey but predominantly on small rodents, and the breeding density varies between years depending on prey abundance
We present results on changes in the breeding population size and breeding results between the years 1996 and 2010 as a contribution to the knowledge of the geographical variation of the breeding biology of Tawny Owls
Summary
There is a considerable interest of how reproductive success varies between years and over longer periods of time. Sometimes they breed in twig nests of Crow Corvus corone, Magpie Pica pica, Sparrowhawk Accipiter nisus and Buzzard Buteo buteo They readily accept nest boxes and may breed near human settlings (Mikkola 1983, Svensson et al 1999, König & Weick 2008, own observations). This makes them well suited for scientific studies and this is probably the main reason why the Tawny Owl is one of the most studied species of birds of prey in Europe. We present results on changes in the breeding population size and breeding results between the years 1996 and 2010 as a contribution to the knowledge of the geographical variation of the breeding biology of Tawny Owls
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
