During the last twenty years marked declines in Peregrine Falcon populations have occurred in many parts of the world (Hickey, 1969). During recent years the peregrine has been placed on the list of Endangered Species. Several factors have been suggested as the cause of its decline. These include changing climatic conditions (Porter and White, 1973), human disturbance (Mattox, pers. comm.), and introduction of chlorinated hydrocarbons as pesticides into the environment (Ratcliffe, 1970). The third factor, introduction of chlorinated hydrocarbons, has occurred on the American, European and Asian continents. Even peregrines nesting in locations far from human population concentrations are exposed to chemical pollutants on migratory flights south, in nesting areas and in the wintering range. Most of the small birds utilized by the peregrine as prey in the north also migrate south every winter, many moving into farming areas where insecticides are frequently used. By feeding in these areas the passerines accumulate substantial amounts of chlorinated hydrocarbons which are stored in fat tissues. As the peregrines feed on these small birds, body levels of chlorinated hydrocarbons gradually increase. If subsequent levels·are high enough, they may cause death (Porter, 1972). In most cases, however, lethal levels are never reached: instead the lower levels produce eggshell thinning and breakage (Porter and Wiemeyer, 1969) which may be an important reason for world-wide decline in peregrine populations (Hickey and Roelle, 1969). Peregrines in the western United States have shown a 20% decrease in eggshell thickness since DDT was introduced (Enderson and Craig, 1974).
| Identifer | oai:union.ndltd.org:BGMYU2/oai:scholarsarchive.byu.edu:etd-8648 |
| Date | 01 April 1975 |
| Creators | Burnham, William A. |
| Publisher | BYU ScholarsArchive |
| Source Sets | Brigham Young University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations |
| Rights | http://lib.byu.edu/about/copyright/ |
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