Related Experiment Videos
DDE residues and eggshell changes in Alaskan falcons and hawks.
Science (New York, N.Y.)
|May 28, 1971
Summary
DDT exposure thinned eggshells in Alaskan peregrine falcons, with higher DDE pesticide levels correlating to thinner shells. This contamination has led to fewer fledged young in tundra and taiga peregrine populations.
Area of Science:
- Environmental Toxicology
- Avian Ecology
- Wildlife Science
Background:
- Organochlorine pesticides, such as DDT, have been linked to adverse effects in wildlife populations.
- Peregrine falcons and other raptors are susceptible to bioaccumulation of environmental contaminants.
- Eggshell thinning is a recognized indicator of pesticide exposure in birds.
Purpose of the Study:
- To investigate the impact of DDT exposure on eggshell thickness in various Alaskan raptor species.
- To correlate levels of DDE (a metabolite of DDT) with observed changes in eggshell thickness.
- To assess the reproductive consequences of pesticide contamination in peregrine falcons.
Main Methods:
- Measuring eggshell thickness in peregrine falcons, rough-legged hawks, and gyrfalcons from different Alaskan regions.
- Quantifying DDE residues in eggs from these species using lipid-based analysis.
- Analyzing the correlation between DDE concentrations and eggshell thickness.
- Monitoring fledging success rates in affected peregrine populations.
Main Results:
- Eggshell thickness was significantly reduced in Alaskan tundra peregrines (21.7%) and taiga peregrines (16.8%) exposed to DDT.
- DDE levels were highest in tundra peregrine eggs (889 ppm) and taiga peregrine eggs (673 ppm), showing a strong negative correlation with shell thickness.
- Aleutian peregrine eggs, rough-legged hawk eggs, and gyrfalcon eggs showed progressively lower DDE levels and less pronounced shell thinning.
- Tundra and taiga peregrine populations have experienced declining fledging success since 1966.
Conclusions:
- DDT contamination has demonstrably thinned eggshells in Alaskan peregrine falcons, with higher DDE levels correlating to greater shell thinning.
- The observed eggshell thinning and reduced reproductive success in tundra and taiga peregrines highlight the ecological impact of persistent organic pollutants.
- Gyrfalcons and rough-legged hawks exhibited lower exposure levels and less impact, suggesting differential susceptibility or exposure pathways.