Over de opzienbarende kolonisatie van de Bosuil Strix aluco in Groningen en Drenthe
Drentse vogels , Volume 5 - Issue 1 p. 43- 47
A census of Tawny Owls in an area of 3800 ha in the northern Netherlands (municipalities of Haren and Eelde, fig. 1) in 1982-91 revealed a strong increase since its settlement in 1984 (fig. 2, fig. 3). Successful breeding was reported nine times. Average clutch size was 3.3 eggs (range 2-4, n=6) and average brood size was 2.5 young (range 1-4, n=6). Earliest begging calls were heard on 17 April. At low densities, Tawny Owls did not respond to play-backs. This method became only successful after the breeding density had increased considerably.
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