DONKERS H (2018) Year-round diet of the Tawny Owl Strix aluco in woodland on poor soils in West-Brabant. LIMOSA 91 (2): 46-60.
From January 2012 through December 2017, pellets of Tawny
Owls were collected on a regular basis at night roosts below
hunting posts in de Rucphense Bossen and Visdonk (Southwestern
Netherlands). The Rucphense Bossen is a 830 ha
conifer plantation, mainly covered by Scots Pine. Here a total
of 8677 prey items were collected and identified. Another
2664 prey items were collected at Visdonk, a nearby area of
fragmented woodland (110 ha), bordered by farmland (Fig. 1).
Woodmice Apodemus sylvaticus (54.3%, based on biomass)
dominated in the diet in both areas, in all years and all seasons
(Fig. 2) followed by Bank Voles Myodes glareolus (14.4%),
birds (11.7%), Rabbits Oryctolagus cuniculus (4.3%), Field
Voles Microtus agrestis (4%), Frogs Rana sp. (3.4%) and Whitetoothed
Shrews (Crocidura russula) (2.8%). All other species
were represented by less than 2%.
After mammals, invertebrates were the most numerous
prey group. Within this group, Minotaur Beetles Typhaeus
typhoeus (60.1%) were most frequently found, followed by
Cockchafers Melolontha melolontha (20.2%).
Contrary to most of the studies that were conducted in
mixed or deciduous woods, small rodents were the most
abundantly represented prey in the pellets in all seasons.
This may be due to the lack of thick groundcover in the study
area which makes it easy to localize and catch small rodents,
even in spring and summer.
In general, old deciduous woodland is considered to be
optimal habitat for Tawny Owls. In the poor coniferous study
area the density of territories however was high (3/100 ha)
and the dominance of a few species throughout seasons and
years might indicate a rich food condition. Unfortunately
information about reproduction is lacking.
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