Náttúrufræðingurinn - 2008, Síða 20

Náttúrufræðingurinn
Fátt er vitað um atferli refa stuttu
áður en þeir drepast af náttúrlegum
orsökum en ekki er ólíklegt að þeir
dragi sig í hlé þangað sem þeir eiga
síður von á truflun. Líklegasta skýr-
ingin á því að svo mörg dýr finnast á
sama stað er sú að þau hafi leitað
skjóls þar til að drepast og ár eða ára-
tugir hafa getað liðið milli þess sem
þau drápust. Hugsanlega hefur
hellirinn ekki verið aðgengilegur
nema í nokkur hundruð ár eftir að
munninn reis úr sæ og grjóthrun svo
komið í veg fyrir frekari notkun. Það
gæti skýrt hvers vegna dýrin drápust
öll á tiltölulega skömmum tíma í
jarðfræðilegum skilningi. Þetta er þó
eingöngu tilgáta.
Enn er þeirri spurningu ósvarað
hvaðan tófan hafi komið til landsins
í upphafi þótt hér hafi verið færð
rök fyrir því að hún hafi frekar
komið um hafís frá Vestur-Evrópu
en frá Grænlandi. Með beinafund-
inum sem hér er lýst opnast sá
möguleiki að svar fáist við þeirri
spurningu, svo framarlega sem
erfðaefnið er nógu heillegt til að það
megi bera saman við erfðaefni mel-
rakka í Vestur-Evrópu frá síðasta
jökulskeiði og erfðaefni núlifandi
refa á Islandi og annars staðar á út-
breiðslusvæði þeirra.
SUMMARY
The oldest known remains of
Arctic foxes in Iceland
Because of its geographical loca-
tion, Iceland harbours few
terrestrial mammals of which all
but the Arctic fox (Alopex lagopus)
were brought willingly or unwill-
ingly to the country by humans. It
has generally been believed that
Arctic foxes have been present
continuously in Iceland since the
end of the Ice Age but so far there
has been no definite proof that the
species lived in Iceland prior to
human settlement. Furthermore,
legends exist of the wilful intro-
duction of Arctic foxes to Iceland
by foreigners as revenge against
Icelanders.
There is indirect evidence that the
Arctic fox was already present in
Iceland when humans settled in the
country about 1100 years ago. In the
first Icelandic lawbook, Grágás,
which was written in the early 12th
century (laws had been passed
down verbally for almost 200 years
prior to that), it was clearly stated
that the Arctic fox could be hunted
anywhere, suggesting that Arctic
foxes were abundant at that time. In
contrast the importation of red fox-
es (Vulpes vulpes), wolves (Canis
lupus) and brown bears (Ursus arct-
os) was strictly prohibited by law.
Furthermore, in the early 20th
century the naturalist Guðmundur
G. Bárðarson found jaws, teeth and
bones of at least five adult foxes and
one fox cub in a layer of subfossil
shells which is assumed to be
2600-2800 years old. However, the
bones were never dated and may
be lost now. Finally, a recent
circumpolar study of Arctic fox
genetic structure suggests that the
Icelandic Arctic fox has been large-
ly isolated from other Arctic fox
populations for a long time, possi-
bly since the end of the Ice Age.
In January 2004, during work to
improve a road at the Hvalsárhöfdi
peninsula in coastal north-western
Iceland, a part of a rock face just above
sea level was removed by explosions.
In the process a small cave at the basal
part of a basalt layer was exposed.
This layer is made of unusually fresh
basalt, 8-10 million years old, no
secondary minerals or signs of
weathering was seen, and the cave
was lined with reddish scoria. In the
scree formed by the scoria of the cave
a total of 7 almost complete skulls of
Arctic foxes were discovered, together
with bones from a number of fish and
birds. Collagen was successfully
extracted from approximately 100 mg
bone powder from 6 of the 7 skulls at
the Archaeological Research Labora-
tory, Stockholm University, Sweden.
Accelerator Mass Spectrometry radio-
carbon datings were subsequently
conducted for the samples at the
Ángström Laboratory, Uppsala Uni-
versity, Sweden. The uncalibrated
results indicated a 14C age of 3485±30,
3350±30, 3390±40, 3330±35, 3270±30
and 3615±35 years for the six skulls,
respectively. Thus it has been establis-
hed conclusively for the first time that
Arctic foxes roamed Iceland long
before human settlement.
The above results raise new ques-
tions as to the origin of the initial
Icelandic Arctic fox population.
During the height of the last glaci-
ation the species ranged from
Alaska in the east to southern
Ireland in the west and as far south
as northern Italy and Crimea. There
was sea ice in abundance in the
North Atlantic, both west and east
of Iceland. Polar bears roamed the
pack ice in search of seals and it is
very likely that Arctic foxes fol-
lowed them onto the ice and scav-
enged scraps of meat left on seal
carcasses. It is quite probable that
Arctic foxes occasionally arrived in
Iceland at the time but due to the
thick ice cap extending 50-120 km
beyond its present day shoreline,
the country would not have been
inhabitable for foxes or their prey.
The same was true of northern
Greenland and the Canadian Arctic
archipelago. At the end of the Ice
Age the ice caps in Western Europe
and Iceland retreated earlier than
the ice caps of northern Greenland
and it is quite possible that the first
Arctic foxes to settle and reproduce
in Iceland actually arrived from
Western Europe rather than from
Canada or Greenland. However,
the question regarding the Icelandic
Arctic fox's origin is still open.
The fact that a number of bones,
both from fish and birds, were
found together with the fox bones
suggests that the cave had fre-
quently been used by foxes to feed
undisturbed, and finally to with-
draw into as death approached.
However, it seems to have been
accessible only for a short period in
geological terms, perhaps a few
hundred years.
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