METHODS USED AT PATUXENT WILDLIFE RESEARCH CENTER 

 TO STUDY THE EFFECTS OF OIL ON BIRDS 



William C. Eastin, Jr. 



Patuxent Wildlife Research Center 



U.S. Fish and Wildlife Service 



Laurel, Maryland 



INTRODUCTION 



The obvious damage to the flora and fauna following an oil spill receives 

 a considerable amount of attention. News media accounts are usually replete 

 with photographic evidence of the disastrous effects of these catastrophes. 

 Although the numbers of dead and oiled animals found at the scene of a spill 

 are somtimes large, the effect on wildlife from the low levels of oil re- 

 maining after cleanup procedures or from continuous low-level contamination 

 in other areas may be equally damaging. However, these low-level exposures 

 are difficult to detect. An understanding of their ecological impact requires 

 scientific attention. Chronic low-level effects of oil on the environment 

 are being investigated by a number of research groups. The Patuxent Wildlife 

 Research Center has focused its oil contamination research on birds. Members 

 of the research group include wildlife biologists, physiologists, and 

 chemists. The purpose of this paper is to present the experimental approaches 

 used by researchers at the Patuxent Center to resolve some of the questions 

 concerning the effects of chronic low levels of oil on birds. 



METHODS AND RESULTS 



Oil can be ingested by birds directly while drinking or feeding, in- 

 gested indirectly via the food chain, or applied to incubating eggs by the 

 adult. The effects of oil on avian species through these routes of exposure 

 were determined in three types of related experiments: 1) indoor pen studies, 

 2) incubator studies, and 3) outdoor field studies. To assess the effects of 

 oil ingestion on birds, investigators monitored several parameters, including 

 mortality, growth (weight gain and wing measurements), plasma enzymes, and 

 liver function. Several routine clinical biochemical techniques for assess- 

 ing damage to mammalian systems were adapted for birds. Thus, measurements 

 were made on plasma enzymes that reflect damage to specific organs such as 

 kidney, liver, and heart. In addition, a technique established for mammals 

 to directly indicate a change in hepatic function was found acceptable for 

 avian species (Patton 1978). Organ damage measured biochemically was con- 

 firmed at both the macroscopic and microscopic level by a pathologist 



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