337 



and attributed it in part to losses resulting from oil spilled by two wrecked 

 tankers in February 1952. 



The history of marine oil transport throughout the world includes many oil 

 spills ( Bourne, 1969) . A few of the major ones in recent years are mentioned here 

 as additional background. Statistics from the Liverjjool Underwriters Association 

 list 19 tanker groundings (with 17 spillages) and 238 tanker collisions (with 22 

 spillages) from June 19&4 to April 1967 (Aldrich, 1970). 



According to the Smithsonian Institution Outer for Short-Lived Phenomena, 

 15,000 to 25,000 oil-affected eiders came ashore on the Wadden Islands, Nether- 

 lands, in February 1969 (Aldrieh. 1970). 



Oil spilletl from the wrecked tanker "Torrey Canyon" in March 1967 off the 

 coast of England killed many tens of thousands of birds. Nearly 8,000 birds were 

 picked up still alive on the English coast alone for attempted rehabilitation 

 (Bourne, 1970). 



When the "Gerd Maersk" was stranded off the mouth of the Elbe River in 

 January 1955 at least 500,000 birds of 19 species were killed, the most abundant 

 being common .scoters (Goethe, 1968). 



Bird losses due to oil imllution have suppressed some local populations for pro- 

 longed periods. Uspenskii (19(>1) reported that more than 30,000 wintering old- 

 .squaw^ perished fnmi oil i)ollution near Gotland Island in the Baltic and that in 

 subsequent years, oldscpiaws had almost completely disaiyi)eared from Swedish 

 Lapland. 



EFFECT OF OIL ON BIRDS AND THEIR HABITAT 



Birds are killed by oil on water. Some survive the contamination, but are dis- 

 comforted and probably reduced in reproductive capability. The extent of oil- 

 ing, type of oil, and the prevailing weather conditions usually determine the fate 

 of these birds. 



The immediate effect of oil is on the birds' plumage. According to Clark (1969), 

 feathers become matted together, destroying the water-repellant property of the 

 plumage and allowing water to replace the air normally trapped in it. When the 

 plumage l)e<"omes oil-soaked and water-logged, birds lost buoyancy and the ability 

 to fly (Erickson, 1963), and diving ducks are unable to dive for foo<l (Chubb, 

 1954). Taning (in Tuck 1960) reported .seeing oil-affected alcids far out at sea, 

 so soaked with water that they could keep only their head and neck above the 

 surface. Some birds drown and are never swept ashore. 



Experimentally oiled ducks greatly increase their metabolic rates to compen- 

 sate for heat lost btx-ause of a breakdown of the insulating properties of the 

 plumage, with heavily oiled ducks losing more than twice the heat of normal 

 ducks (Hartung, 1967). Because oiled ducks either do not or can not increase 

 their feetling activity to compensate for the increased energy demands and be- 

 cause their fat reserves, if any, are quickly depleted, they suffer from accelerated 

 starvation. Accelerated starvation during periods of low temperatures is usually 

 fatal for mo.s't waterbirds. Tuck (1960) claimed that a patch of oil, one inch in 

 diameter, on the belly of a murre was sufficient to destroy the insulating air 

 pocket and cause death from exposure to the chilling effect of the sea. 



Sticky globs of oil were found on the beaches of Kodiak Island following the 

 oiling of birds there in February and March of 1970. and .Tames H. King (Personal 

 communication to Regional Director, P.SFW, Portland, Oregon, from J. G. King, 

 1970) sjieculated that this oil could kill birds bv adhering to their bills, mouths, 

 and mres and thus fatally impair breathing and feeding. 



Although the relative toxicity of North Slope crude oil to birds is not known, 

 many refined petroleum materials are known to be lethal ly toxic to waterbirds. 

 Hartung and Hunt (1966) demonstrated that various industrial oils caused lipid 

 pneumonia, gastor-intestinal irritation, fatty livers, and adrenal cortical hyper- 

 l>iasia when fed to ducks in single doses that were regarded to be less than 

 that which might be ingested during i)reening of oiled plunnges. AKhougli the 

 toxicity varied among the oils tested, all oils were more toxic when the captive 

 ducks v»'ere imder stress from crowding and low temperatures. Beer (1968) 

 observed comparable necrotic conditions among alcids retrieved fom the "Torrey 

 Canyon" spill. Some components of crude oils are carcinogenic (Rlumer, 1969). 



Stress is unlikely to be directly responsible for the deaths of birds but it is an 

 important contril)uting factor (C'ark. 1969). All of tlif> combined effects of 

 cold, starvation, toxic effects of oil. disturbance, internal injury and. presum- 

 ably, fright combine to cau'^e acute stress. The bird's resistance to secondary 

 infections and the toxic effects of oil are reduced, often beyond the threshold 



