The Braer - Origins of Ringed Birds
A total of 39 ringed birds were recovered as a result of the Braer oil spill. Thirty-four were Shags, fifteen from the nearby Sumburgh colony, and while this was the worst hit colony, birds from colonies throughout Shetland, (and as far away as Orkney), suffered mortalities.
The two main groups of birds affected by the oil spill
were locally resident species (e.g. Shags, Tysties, Eiders,
etc.) and winter visitors from the north (e.g. Long-tailed
Ducks, Great Northern Divers). Of the local resident
species Shags have been a target species for ringing effort
and this was reflected in the numbers of ringed birds found.
None of the winter visitors found dead were ringed e.g. Long-tailed
Ducks, Great Northern Divers, etc., probably because very few
individuals of these species have been ringed in their natal areas.
There were 15 birds recovered that had been ringed at the colony at Sumburgh, 11 from Fair Isle, 6 from Foula and singles from Hermaness in Unst and Swona in Orkney. This was 3.5% of the Shags collected. All of the colonies in Shetland where any significant numbers of Shags have been ringed are represented. It is not surprising that the bulk of the recoveries come from the Sumburgh colony as this is by far the closest to the site of the wreck. However because a chick was ringed in a colony it does not necessarily mean that the bird will return to that colony to breed, but it is likely that a large proportion of Shags will do so. Four birds ringed as breeding adults (2 from Sumburgh and singles from Foula and Fair Isle), were recovered. It was previously assumed that a large proportion of breeding Shags were sedentary, remaining in the vicinity of their colony throughout the year. If this had been the case then the bulk of the dead birds would have been from the colony at Sumburgh which would consequently have been wiped out by the spill. In fact, the recoveries show that there were birds present from over a wide area and that breeding adults from other colonies were in the area at the time of the spill. It is possible that birds from remote colonies such as Fair Isle and Foula are inclined to move to the Mainland during winter as the outer isles will be particularly exposed to severe weather conditions.
Shag, the species most affected by the spill
A single ringed bird was recovered during the spill. This had been ringed as a breeding female on Fair Isle in 1987. Presumably Eiders move to the more sheltered areas of Mainland during the winter to avoid the exposed coastlines of the outer isles. If a significant number of the casualties were established breeders rather than juveniles, recovery of the population could be long term.
Two ringed birds were recovered during the incident, one ringed and recovered within the Scalloway Islands, the other a bird ringed as a chick on Isbister Holm off Whalsay in 1982 and recovered at Quendale. This was quite a significant movement for a Black Guillemot as most are very sedentary and represents the furthest movement of any Tystie in the records of the Shetland Ringing Group.
A single bird was recovered, having been originally ringed in the
Farne Islands in 1964. This is the oldest Kittiwake recorded in the
British ringing scheme. Fairly large numbers of Kittiwakes have been
ringed in some of the Shetland colonies over the years and the fact
that none of these locally ringed birds were found amongst the 136
birds collected in the incident would suggest that many of the individuals
involved were not from Shetland colonies. The Shetland Ringing Group has
no previous records of birds from Shetland colonies being recovered in
the islands in winter. The only recovery of a Kittiwake in Shetland
in winter was of a bird from a colony in West Greenland. Birds from S
hetland colonies have been recorded in the southern North Sea and
France during the winter.
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