Náttúrufræðingurinn - 1952, Side 40

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NÁTTÚRUFRÆÐINGURINN
existed in this country in the 18th century. But as the fulmar’s spread started in the
first half of tliat century (cf. its colonization of the Vestmannaeyjar) it is not im-
probable that it had already colonized other sites before 1800, although this is not
mentioned in contemporary sources. We are far better informed about the history of
the Icelandic fulmar population in the 19th and the present centuries. We know that
during this period the fulmar has been steadily increasing and, at the same time, has
constantly been colonizing new localities along the indented and rugged coastline of
Iceland.
The spectacular increase and rapid spread of the fulmar in the North Atlantic,
which has not only occurred in Iceland but also in the British Isles, the Faroe Islands
and Norway, is an almost unique phenomenon among birds. Various causes of the ful-
inar’s spread have been suggested, one being that whaling and trawling in Northern
waters liave completely changed the fulmar’s conditions of life in these regions by
providing it with a constant and almost unlimited source of food. As far as I know
Bjarni Sæmundsson, the Icelandic fishery biologist, was the first to point out (cf. Zoo-
log. Medd. fra Island XVI, 1934, and Fuglarnir, 1936) that a connection between the
fulmar’s increase and spread and the large-scale whaling and later trawling in Nor-
thern waters was not improbable. James Fisher also adheres to this theory and in his
recent monograph on the fulmar (Collins, London 1952) has substantiated it in a very
convincing way.
In Iceland the fulmar shares the „bird-cliffs” with other sea-birds. But in many
places it also occupies sites where no other species are present. Outlying islands and
headlands were first colonized by the fulmar but in course of its spread it has pene-
trated farther and farther into bays and fjords and even to inland localities. Thus in
many parts of the country it is now occupying cliffs a godd distance from the sea. In
the districts Mýrdalur and Öræfi in S. Iceland it even breeds on cliffs no less than 14
and 18 km from the sea respectively. Where the fulmar shares the cliffs with other sea-
birds it is mainly found breeding in the upper parts of the cliffs and in some places it
also breeds on the flat surface on top of steep rocky islands or stacks. Caverns, crevices
or crannies in the cliffs are favoured nesting sites, but ledges or shelfs with rich vege-
tation (angelica, scurvygrass) also attract the fulmar. The clutch consists of one egg
only. Nests with two eggs are, however, not infrequently to be found, but in such
cases the eggs may have been laid by two different females, and as a rule only one of
the eggs is incubated. In some cases the egg is laid on the bare rock but more often a
distinct nest hollow is formed in soil or sand, often lined with pebbles or bits o£ dead
vegetation. Most of the eggs are laid between the lOth and 20th of May. About or just
after the 20th of August the young begin to leave the nests, and about the middle of
September the fulmar has entirely left the colonies in this country. After that fulmars
are not to be seen in or about the breeding-cliffs for some time. But during early
November the fulmar starts revisiting the cliffs now and again, and these visits grow
more and more frequent as the winter passes. It is particularly in thawy or mild
weather that the fulmar visits the breeding-cliffs in winter, but less so during frosty
spells. The fulmar can therefore be said to be a resident bird in Iceland, although it
is not unlikely that in winter a part of the population, especially the young, may
move a little southward in the Atlantic.