Swennen C. (1974) Observations on the effect of ejection of stomach oil by the Fulmar Fulmarus glacialis on other birds. ARDEA 62 (1-2): 111-117

Some experiments are described in which a Fulmar Petrel Fulmarus glacialis fouled a number of healthy birds, viz. 3 Herring Gulls Larus argentatus, 2 Guillemots Uria aalge and 1 Common Gull Larus canus with stomach oil. In all cases the feathers which had been hit by the oil became wet during bathing. The waterlogged birds sank deep into the water, were unable to fly and finally died of exposure or drowning. Only one of the birds, a Guillemot, survived the experiment by being nursed for a long time in a dry environment. It is clear that, whenever during a conflict the oil from the stomach of a Fulmar is ejected on the feathers of another bird, this is similar to the fatal contact with fuel oil. It is therefore remarkable that those birds do not show any sufficient reaction to a threatening Fulmar and are not able to remove the sticky stuff from their feathers.