Náttúrufræðingurinn - 1997, Side 26

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Finnur Guðmundsson 1951. The effect of the
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■ SUMMARY
OBSERVATIONS ON WINTER
FOOD HABITS OF SHORT-EARED
OWL ASIO FLAMMEUS IN
ICELAND
The Short-eared Owl is a recent immigrant to
Iceland. The first breeding record is l'rom 1912
(Finnur Guðmundsson 1951) (Fig. 1). In the next
decades it spread and is now found breeding in
most parts ofthe country (Hagemeijer and Blair
1997). No microtines occur in Iceland and the
only rodent common outside human dwellings is
the Wood Mouse (Apodemus sylvaticus) so the
food situation is quite different from what the
Short-eared Owl experiences in Northern-Eu-
rope (Fig. 2). The aim of this paper is to report
observations on the winter food habits of the
Short-eared Owl in Iceland. A total of 81 pellets
were collected at roost sites in four areas in
Southwest- and West-Iceland (Table 1). Re-
mains of 106 vertebrates were found in the pel-
lets including 53 Wood Mice, 51 Purple Sandpi-
pers (Calidris maritima), one Turnstone
(Arenaria interpres) and one Snow Bunting
(Plectrophenax nivalis). Using % biomass, birds
were the most important food item weighing
69% of the total catch (Table 2). This is quite
different from the situation in Northern Europe
where birds are usually less than 10% and
microtines dominate the catch. The study areas
differed. In the southwest only Wood Mice were
found. At Stykkishólmur in the west Wood
Mice measured 20% by biomass, the main prey
there was the Purple Sandpiper. On the island
Hvallátur the main prey item was also the Purple
Sandpiper and Wood Mice amounted to 7% by
biomass (Table 2).
PÓSTFANG HÖFUNDAR/
AUTHOR'S ADDRESS
ÓlafurK. Nielsen
Náttúrufræðistofnun Islands/
Icelandic Institute of Natural History
Pósthólf/Box 5320
IS-125 Reykjavík
88