were contaminated with oil and many of them 

 were unable to fly. Some of the eggs laid along 

 the high-tide mark failed to hatch after they 

 became contaminated with oil (Rittinghaus 

 1956). 



After ingestion of a relatively nontoxic lu- 

 bricating oil (2 g/kg), one mallard (Anas platy- 

 rhynchos) and two Pekin ducks stopped lay- 

 ing for about 2 weeks. Very small quantities 

 of oil coated on mallard eggs reduced their 

 hatchability to 21%, compared with 80% for 

 unoiled eggs. Experimentally oiled mallards 

 continued to incubate their clutches, but their 

 eggs failed to hatch (Hartung 1965). 



In an experimental application to test the 

 effects of 2,4-D and diesel fuel on eggs of ring- 

 necked pheasants (Phasianus colchicus), there 

 was no adverse effect by the 2,4-D on hatch- 

 ability, but application of the diesel fuel re- 

 duced hatchability to zero (Kopischke 1972). 



Behavior 



Exposure to oil causes some obvious 

 changes in behavior patterns of birds because 

 they abandon all activities to attempt to clean 

 the oil from their feathers by preening (Smith 

 1975). There may be other serious but less 

 readily observed direct effects that influence 

 the birds' ability to locate food, to migrate, or 

 to perform other essential activities. 



As discussed earlier, small amounts of oil in 

 the water cause significant changes in be- 

 havior of certain marine organisms. Modified 

 behavior among any of the numerous species 

 of animals in the food webs may have serious 

 indirect implications for the welfare of marine 

 birds that depend upon them. 



Organochlorines 



By 1971, and perhaps earlier, it became un- 

 likely that any bird dependent upon marine 

 food webs anywhere in the world was free of 

 contamination by the synthetic organo- 

 chlorine compounds that have become ubi- 

 quitous pollutants in the global ecosystems 

 (Sladen et al. 1966; Risebrough and Berger 

 1971; Began and Bourne 1972; Bourne and 

 Bogan 1972; Bennington et al. 1975; Rise- 

 brough 1977; Walker 1977; White and Rise- 

 brough 1977). More information is available 

 on the global distribution patterns of organo- 



chlorines than for other chemicals in marine 

 birds. Several direct biological effects of or- 

 ganochlorines on marine birds are known. 

 Other relevant information is available on the 

 distribution of these pollutants in estuarine, 

 freshwater, and terrestrial ecosystems, as 

 well as their biological effects on other birds. 



The most abundant synthetic organo- 

 chlorine compound in tissues and eggs of ma- 

 rine birds is frequently p,p '-DDE, a derivative 

 of p,p'-DDT, which is the principal component 

 of the commercial insecticidal mixture (Rise- 

 brough et al. 1968; Jensen et al. 1969; Koeman 

 et al. 1969). Other DDT compounds fre- 

 quently present in marine birds arep,p'-DDD, 

 p,p'-DDT, and o,p'-DDT (Bennington et al. 

 1975). 



Polychlorinated biphenyls (PCB's), or 

 chlorobiphenyls, consist of a mixture of com- 

 pounds differing in chlorine content and the 

 position of chlorine atoms on the parent bi- 

 phenyl molecule. Pentachlorobiphenyls and 

 hexachlorobiphenyls usually constitute the 

 majority of the chlorobiphenyls present in 

 marine birds, but trichlorobiphenyls and tet- 

 rachlorobiphenyls are occasionally present 

 (Risebrough and de Lappe 1972; White and 

 Risebrough 1977). 



A number of other synthetic organochlorine 

 compounds have been detected in marine 

 birds, but almost always at levels substan- 

 tially lower than those of the DDT and PCB 

 compounds. Hexachlorobenzene (HCB), which 

 has been found in tissues of great cormorants 

 (Phalacrocorax carbo), sandwich terns 

 (Thalasseus sandvicensis), and common eiders 

 (Somateria mollissima) from coastal areas of 

 the Netherlands (Koeman and van Genderen 

 1972; Koeman et al. 1972a), has been consid- 

 ered a potentially hazardous marine pollutant 

 (National Academy of Sciences 1975b). The 

 HCB is used as a fungicide but may enter the 

 marine environment in significant quantities 

 as a component of the tarry waste products 

 from the manufacture of chlorinated hydro- 

 carbons such as perchloroethylene and carbon 

 tetrachloride that are frequently discharged 

 at sea (Environmental Protection Agency 

 1973). 



Chlorinated styrenes were identified by gas 

 chromatography/mass spectrometry in tis- 

 sues of common eiders, sandwich terns, and 

 great cormorants from the Netherlands (Ten 

 Noever de Brauw and Koeman 1972) and in 



