Elstu þekktu leifar melrakka á Íslandi

Elstu þekktu leifar melrakka á Íslandi
Páll Hersteinsson, Veronica Nyström, Jón Hallur Jóhannsson, Björk Guðjónsdóttir og Margrét Hallsdóttir
Bls: 13–21 1.–2. hefti 76. árg. 2007

Vegna legu Íslands eru hér fáar tegundir villtra landspendýra. Allar nema ein hafa þær borist hingað fyrir tilverknað mannsins, ýmist viljandi eða óviljandi. Undantekningin er tófan Alopex lagopus (1. mynd) sem þó hefur vantað sönnur fyrir að hafi komist hingað af sjálfsdáðum fyrir landnám manna. Þrátt fyrir það hefur því lengi verið haldið fram að tófan hljóti að hafa verið hér þegar landnám manna hófst og hafi að öllum líkindum verið hér allt frá því að síðasta jökulskeiði lauk.
The oldest known remains of Arctic foxes in Iceland

Because of its geographical location, Iceland harbours few terrestrial mammals of which all but the Arctic fox (Alopex lagopus) were brought willingly or unwillingly 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 introduction 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 foxes (Vulpes vulpes), wolves (Canis lupus) and brown bears (Ursus arctos) 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 largely isolated from other Arctic fox populations for a long time, possibly 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 Laboratory, Stockholm University, Sweden. Accelerator Mass Spectrometry radiocarbon datings were subsequently conducted for the samples at the Ångström Laboratory, Uppsala University, 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 established conclusively for the first time that Arctic foxes roamed Iceland long before human settlement.

The above results raise new questions as to the origin of the initial Icelandic Arctic fox population. During the height of the last glaciation 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 followed them onto the ice and scavenged 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 frequently been used by foxes to feed undisturbed, and finally to withdraw into as death approached. However, it seems to have been accessible only for a short period in geological terms, perhaps a few hundred years.