Fróðskaparrit - 01.01.2001, Blaðsíða 125

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ÚTBREIÐSLA OG TAL AV MÚSABRÓÐUR (TROGLODYTES) í FØROYUM
Stóra Dímun
Fig. 1. The Faroe Islands. Dots give the locations of
selected study plots on Mykines, Streymoy (Tjørnuvík
and Haldarsvík), and Fugloy (Kirkja).
plateaus, being dominated by different
kinds of grassland (mostly of heath type)
except at the highest altitudes where the
vegetation is sparse. The climate is oceanic
with cool summers (mean temperature
11°C in July-August), mild winters (4°C in
January-February), high mean annual pre-
cipitation (about 1500 mm; nearly all of it
falls as rain ), frequent and strong, mostly
W-SW, winds, and often mist. For details
on the environmental conditions on the
Faroes, see Rutherford (1982).
Material and inethods
Since 1978 I have visited the Faroes > 30
times, each island on several occasions
(Lítla Dímun only once), and effectively all
parts of the islands. Much time (especially
in the 1980s) was devoted to studies of in-
dividually colour-banded wrens in four se-
lected small plots (Fig. 1), v/z. W of the vil-
lage on Mykines in an area dominated by
seabird colonies, on northern Streymoy at
Tjømuvík in immediate vicinity of the set-
tlement and S of Haldarsvík in an outfield
area with plenty of stone walls and screes,
and at Kirkja on Fugloy in an area encom-
passing the settlement and the infield, and
northwards the outfield steep slopes with
ravines along the coast. Throughout the
study wrens were systematically searched
for and recorded in all districts of the
Faroes. The wren may be heard singing at
all times of the year and the loud and vehe-
ment song makes it relatively easy to estab-
lish its presence and the approximative lo-
cation of singing by, presumably territorial,
males; subject to terrain and weather condi-
tions. The censuses were carried out in
March-July and I frequently used a tape-
recorder and play-back technique. In the
smaller settlements all singing males in the
village and the surrounding infield (and
even more distant ones) could often be
heard from a single vantage point, and re-
peated visits yielded reasonably reliable es-
timates of numbers. Censuses in the out-
field habitats and along coastal cliffs were
much more problematic because of dis-
tances and difficulties in accessability. For
instance, under favourable condition (i.e
calm and clear weather) males singing from