Improving Detection of Pesticide Poisoning in Birds

Birds and Pesticides Birds are an important and visible part of our environment and serve as sentinels of general environmental health. In North America, and in many other developed countries, most bird species are protected from unlicensed taking or kill of individuals. Yet one estimate of pesticide effects on U.S. farmland—considered conservative by many avian biologists and advocates—states that as many as 72 million birds die each year as a result of pesticide exposure (Pimentel 2001). Our ability to refine this estimate or to predict pesticide impacts more accurately is hampered by the difficulty of gathering data, identifying, and assessing pesticide effects on birds in reallife scenarios. Birds are extremely mobile, and it is difficult to exclude them from areas that are treated with pesticides. Whether in agriculture—where bird species attracted to agricultural pests can be economically important for the control of such pests (Kirk et al. 1996, Tucker 2002)—or in forestry, parks, or backyards, birds and pesticides intersect. Birds suffering from lethal or sublethal pesticide effects often escape the notice of humans. When they are noticed, some are brought in to rehabilitation centers. The wildlife rehabilitation community can become a valuable source of information. Research scientists and cooperators from government and industry are working with academic and nonprofit organizations to provide rehabilitators and wildlife professionals with the tools and resources to improve their knowledge of, and ability to report, pesticide incidents. This paper will discuss the science behind the effects of pesticides on birds, with special emphasis on cholinesterase inhibition, and provide practical information for rehabilitators and others interested in responding to suspected avian pesticide poisonings. While the focus here is birds, much of the information can easily be applied to other taxonomic groups. Mammals, fish, amphibians, and reptiles have all been reported as casualties following pesticide field trials, and biologists around the world are sounding an alarm about the state of reptile and amphibian diversity and population numbers. Birds clearly are not the only taxon under fire.