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Avian Mortality at Oil Pits in the United States: A Review of the Problem and Efforts for Its Solution


Oil production operations produce waste fluids that may be stored in pits, open tanks, and other sites accessible to wildlife. Birds visit these fluid-filled pits and tanks (“oil pits”), which often resemble water sources, and may become trapped and die. The US Fish and Wildlife Service (USFWS) has a program to reduce these impacts by locating problem pits, documenting mortality of protected wildlife species, and seeking cleanup or corrective action at problem pits with the help of state and federal agencies regulating the oil industry. Species identification and verification of protected status for birds recovered from oil pits are performed at the USFWS National Fish and Wildlife Forensics Laboratory. From 1992 to 2005, a minimum of 2060 individual birds were identified from remains recovered from oil pits, representing 172 species from 44 families. The taxonomic and ecological diversity of these birds indicates that oil pits pose a threat to virtually all species of birds that encounter them. Ninety-two percent of identified bird remains belonged to protected species. Most remains identified at the Forensics Laboratory were from passerines, particularly ground-foraging species. Based on Forensics Laboratory and USFWS field data, oil pits currently cause the deaths of 500,000–1 million birds per year. Although law enforcement and industry efforts have produced genuine progress on this issue, oil pits remain a significant source of mortality for birds in the United States.

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This article is based on the work of Special Agents of the U.S. Fish and Wildlife Service Office of Law Enforcement, who perform the difficult and essential tasks of inspecting oil pits and recovering bird remains. In particular, I wish to thank Special Agents K. Garlick, R. C. Lee, Jr., T. McKay, M. Medina, S. Middleton, and G. Mowad for their leadership in this area and for providing unpublished reports. P. Ramirez, Jr., of the U.S. Fish and Wildlife Service Environmental Contaminants Program and R. Lamdin of the U.S. Environmental Protection Agency RCRA Program provided useful information and advice. R. C. Laybourne and B. A. Sabo developed the feather cleaning methods used at the Forensics Laboratory and contributed to the identification database reported here. G. Espinoza, L. Saturen, and M. E. Sims assisted with the cleaning and identification of oiled bird remains.

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Correspondence to Pepper W. Trail.

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Trail, P.W. Avian Mortality at Oil Pits in the United States: A Review of the Problem and Efforts for Its Solution. Environmental Management 38, 532–544 (2006).

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  • Bird mortality
  • Oil
  • Petroleum
  • Contaminants
  • E&P wastes
  • Pollution
  • Law enforcement
  • Forensics
  • Migratory Bird Treaty Act
  • RCRA