two reports about the fate of sea birds affected by oil slicks reveal a very sorry picture about their survival after they are released from captivity. In the uk , for example, only one per cent of guillemots (a sea bird) survived the first year of release. In the Netherlands, the figure stood at 20 per cent. Normal breeding success rate of guillemots is over 90 per cent.

Birds affected by oil slicks are treated according to their species and the type of oil in the spills. In the uk , guillemots are treated externally with a warm bath in a special liquid, followed by removal of all oil residues by pressure rinsing with warm water. Ingested oil is removed by administering a mix of salt and glucose with activated charcoal and fine kaolin (a fine white clay used as absorbent). The birds are then released. Before the birds are released, metallic rings are clamped around their legs. The reports are based on comparing the subsequent reports with those of healthy wild birds ringed previously.

In his study, C Wernham, ornithologist in the uk , could only make 77 recoveries from 2,912 rehabilitated guillemots since 1985. From this, Wernham estimates that only 0.6 per cent of the rehabilitated birds survived their first year. This is between 0.7 per cent and 1.3 per cent of what is normally expected for healthy birds.

Another study by C J Camphuysen, ornithologist from the Netherlands, had 108 recoveries out of 1,723 rehabilitated guillemots ringed in Netherlands since 1988. He compared these figures with 2,176 birds ringed as adults at the colony on the Isle of May in the Firth of Forth, Scotland. The study concluded that 22 per cent of the rehabilitated birds survived their first year.

However, bird welfare organisations do not bother with this data. For them, even a survival rate of one per cent is good enough. At the same time, such low survival rates are not observed in all birds. Mute swans ( Cygnus olor ) and penguins ( Sphensicus demrus ) are often treated successfully, with up to 84 per cent of the rehabilitated birds surviving.

There are various reasons for the death of sea birds released after treatment as the effect of oil varies from species to species. For example, the toxic effect of the oil ingested after preening (a natural practice in birds for the maintenance of feathers) leads to some physiological imbalance as the by products of oil enter various organs. Another possible reason is that the birds are not able to regain waterproofing of their feathers.

The two ornithologists suggest that since the oil comes from the illegal release or accidents on the part of oil companies and carriers, better detection of tank-cleaning operations of fuel tanks, especially in the case of tankers, should be international priority. They also suggest that released birds should be ringed and annual ringing of wild healthy birds should also continue so that colonies of birds involved in the oiling incident can be identified.