Date of Award
Master of Science (MS)
Wildlife and Fisheries Biology
Bowerman, William W
Johnson , Alan R
Foltz , Jeffrey W
This study was conducted to determine levels of lead and mercury in the raptors of the South-eastern Peruvian Amazon. The study took place within the Los Amigos Conservation Concession in Madre de Dios, Peru. Eighty-six raptors from among sixteen species were captured with Bal-Chatri traps. From each individual, feather samples were obtained for mercury analysis and blood was taken for lead analysis. Each raptor was then released without incident or injury.
Mercury amalgamation for gold extraction is widely used by small-scale, transient mining operations, which are numerous along the rivers and creeks in the tropical forests and other locations in Latin America. These mining operations have a high waste output of mercury into the water and the air. Mercury which is not bound to gold is dumped into the waste water which returns to the river; and mercury which is bound to gold is later burned off to purify the gold. Once elemental mercury is released into the environment, it cannot be cleaned up. It persists for decades, even centuries after the mining has ceased.
Predatory birds are useful for representing the contamination of the ecosystem at levels higher than mammalian bioindicators. The use of feathers to evaluate exposure of birds to heavy metals like mercury is a common method of analysis. During this investigation, a combination of tail and breast feathers were analyzed from each individual sampled.
It was determined that 81 of the raptors sampled had elevated mercury levels, with many at or above the level known to cause reproductive symptoms in other species. No toxic reference values exist for any of the species sampled. Further study is required to determine if these levels represent a significant threat to raptors.
Blood samples were analyzed for lead concentrations. Lead levels were consistant with or slightly above background levels, with the exception of one individual. This individual appeared healthy and normal upon capture, although his lead levels were consistant with those known to cause symptoms in other species. Probable causes for this individual's elevated blood lead level include having survived being shot with lead shot, ot having consumed a prey item which had been shot with lead shot.
The results of this study will provide insight as to the threat to raptors from mercury and lead from gold mining activity. The results will be reviewed by Peruvian agencies responsible for ecosystem monitoring. This study, among others, may lead to the control of mercury use for gold mining in the Amazon.
Shrum, Peggy, "ANALYSIS OF MERCURY AND LEAD IN BIRDS OF PREY FROM GOLD-MINING AREAS OF THE PERUVIAN AMAZON" (2009). All Theses. 753.