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| American white pelicans were negatively impacted by DDT. |
During the mid-20th
century, DDT (dichlorodiphenyltrichloroethane) was a highly used insecticide that was detrimental to the survival
of populations of fish-eating birds in North America. The chemical was absorbed by aquatic
organisms, and would then bioaccumulate through the food chain. Alarmingly high concentrations were found in
top avian predators, including raptors and, more importantly to this blog post,
pelicans. High concentrations of DDT
resulted in egg-shell thinning, and since pelicans use their webbed feet to
incubate their eggs, they were literally crushing their eggs. Population sizes of brown pelicans and
American white pelicans plummeted.
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| DDT was sprayed excessively, as shown in this photo. |
Fortunately, in 1972, the federal government recognized the impact of
DDT, and the use of the chemical was banned. By the 1980s, pelican populations were
rebounding. Both species of North
American pelicans are now protected under the Migratory Bird Treaty Act of 1918.
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| This American white pelican chick and its sibling may not have survived had it not been for the ban of DDT. |
After DDT was banned, are the egg shells still thin or did they recover?
ReplyDeleteMichele, do you know if other Pelecaniformes have been affected similarly by the presence of DDT, or if it was mainly the Pelicans?
ReplyDelete