Effect of nest-box relocation on predation of Tengmalm's owl Aegolius funereus nests in an area of boreal forest in Hedmark, Norway

  • Published source details Sonerud G.A. (1993) Reduced predation by nest box relocation: differential effect on Tengmalm's owl nests and artificial nests. Ornis Scandinavica, 24, 249-253


In 1971, 28 nest boxes for Tengmalm's owl Aegolius funereus were erected in an area of boreal forest in Hedmark (61°05'N, 11°50'E), south-eastern Norway (see Sonerud 1985). Although the initial rate of nest predation was around 33%, during 1975–1983 over 85% of nests were predated, potentially as a consequence of predators such as the pine marten Martes martes remembering the location of boxes where they had found food in previous years. This study investigated whether relocating boxes had any effect on nest predation rates.

During 13–17 November 1983, 14 nest boxes were selected at random and moved to new sites 50–200 m away within the same forest stand. The remaining boxes were left unmoved, as controls. In autumn 1987, the experiment was reversed, with the 14 ‘control’ boxes moved to new sites 110–370 m away (not necessarily within the same forest stand) between 30 September and 2 October. The remaining boxes (which had been relocated during October 1985, as part of another experiment) were left where they were. Relocated boxes were not visible from their original locations, but were erected on the same tree species, where possible.

Of the 14 boxes relocated in 1983, five were used by owls during 1984–1985, and two (40%) of these nesting attempts were predated, which was a significantly lower proportion than during 1975–1983 (100%; n = 13 nesting attempts). In contrast, five of six (83%) nesting attempts in control boxes were predated during 1984–1985, which was not significantly different to the proportion predated during 1975–1983 (75%; n = 16). Following their relocation in 1987, none of the four nesting attempts in former control boxes during 1988–1990 was predated. During the same period, one of the two nesting attempts in boxes not moved in 1987 was predated.
Sonerud G.A. (1985) Risk of nest predation in three species of hole nesting owls: influence on choice of nesting habitat and incubation behaviour. Ornis Scandinavica, 16, 261–269. For our summary of this paper, see   
Note: If using or referring to this published study, please read and quote the original paper, the abstract of which can be viewed at:

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