Náttúrufræðingurinn - 1980, Side 176

beginning of June, first chicks hatching late
June, and first chicks flying in third week of
July. The breeding season of great many
pairs is extended by egg-collecting for
human consumption. By late August most
terns have moved away from the islands. In
1908 Hörring indicated that relatively few
Arctic Terns nested on Flatey itself, but
mainly in the other islands. Relatively few
tems nested between 1965 and 1973,
on Flatey in particular. In 1973 a great in-
crease took place, but the terns arrived
noticeably late that summer. The same year
a big decline occurred at Svefneyjar islands,
3.5 km away from Flatey, where Ravens
were unusually common and troublesome
by the way of stealing eggs. Thus, predation
may have been the reason for a mass move-
ment to Flatey, where feeding conditions
also are better as shoals of Sandeels (Ammo-
dytes, Hyperoplus) are more common.
Puffin (Fratercula arctica): In spring first
individuals seen in third week of April
(1975: 19.4.; 1976: 19.4.; 1977: 22.4.). Very
few pairs nested on Flatey itself, but
common nesting species in most of the other
islets (see Fig. 4). First fledglings seen on the
sea around 10. August. By late August the
numbers of Puffins have greatly declined.
Black Guillemot (Cepphusgrylle): My main
purpose on Flatey was studying this species.
Therefore it is treated in somewhat more
detail.
Not seen in any numbers throughout
winter. Start attending nesting areas
regularly in March (1976: 11.3.; 1977:7.3.),
9—10 weeks before beginning of laying. The
very first eggs were laid in third week of May
(1975: 18.5.; 1976: 21.5.; 1977: 17.5.). About
50% of the population had laid by the
beginning of June.
The numbers of brecding pairs have
fluctuated greatly this century. Interplay of
two introduced predators (Mink, Mustela
vison, and Brown Rat, Rattus norvegicus) is
thought to have been the main cause for
these changes (discussed more fully later).
Table II and Fig. 5 show the number of
breeding pairs and their distribution 1940 to
1978. The very first fledglings are seen on the
sea around 20. July, and by 20. August most
chicks have left their nest-sites. Between
1973 and 1978 (inclusive) 2314 Black
Guillemots were ringed in the study area.
Two of these birds were recovered in SW.
Greenland (Petersen 1977), and two others
on the east coast of Greenland.
Raven (Corvus corax): Attempt to nest
nearly every year in the islets south of Flatey.
The eggs or chicks always destroyed since
Ravens are claimed to be notorious egg
predators.
Redwing (Turdus iliacus): Not known to
have nested until c. 1962 (1 pair). Then not
until 1976, but annually thereafter, on
Flatey only.
Wheatear (Oenanthe oenanthe): Primarily
through-migrants, first birds observed end
of April/beginning of May (1975: 7.5.; 1976:
28.4.; 1977: 3.5.). Very rare breeders, and
only on Flatey. Hörring mentions only a few
pairs in 1908, but S. Gunnlaugsson and J.
Bogason recalled them as common breeders
for most of the first half of this century. From
1965 onwards Wheatears have steadily
declined in numbers.
Meadow Pipit (Anthus' pratensis): Mig-
rants, first birds arriving in third week of
April (1975: 20.4.; 1976; 21.4.; 1977: 23.4.).
Breed over the whole of Flatey, only a few
pairs in the other islets. An uncommon
breeder in 1908, a common breeding species
in 1942.
White Wagtail (Motacilla alba): Start ar-
riving in spring in late April/beginning of
May (1975: 4.5.; 1976: 22.4.; 1977: 28.4.).
Nest over whole of Flatey but more so on the
western half. Nests usually situated in cliff
crevices, stone walls, house walls, and screes.
Nests have never been found in the other
islets. No apparent change in status since
1908.
Snow Bunting (Plectrophenax nivalis): In
flocks on Flatey in winter. Common brecd-
ing species, nesting particularly in screes,
but also in stone and house walls. The
numbers of nesting Snow Buntings appear
to have fluctuated dramatically this cen-
tury. Hörring mentions them nesting in
great numbers in 1908. During c. 1910—
1940 S. Gunnlaugsson and J. Bogason
agreed on Snow Buntings being uncommon,
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