SILENT SPRING: THE DYING ROBINS OF MSU
In Silent Spring, Rachel Carson refers to numerous case studies and examples of the negative impacts of pesticides. One prominent example is the case of the dying robins on the campus of Michigan State University.
Here the story of Rachel Carson connects with that of an MSU faculty member, Professor George Wallace. Wallace, an ornithologist, and his graduate students John Mehner and Richard Bernard, collected birds—mostly robins—from MSU and surrounding suburbs from the mid-1950s into the 1960s. The birds were found either dead or dying in tremors. Tests on many of the birds’ carcasses revealed elevated levels of the pesticide, DDT.
In the late 1950s and 1960s, DDT was being sprayed by plane and from trucks at MSU and elsewhere in Lansing in an attempt to control Dutch Elm Disease.
Elms are a beautiful shade tree and MSU had over 5,000 elms on its campus. Dutch Elm Disease is caused by a fungus, which is spread by elm bark beetles that burrow through the bark and move from tree to tree. DDT was being used to kill the beetles, in the hope of restricting the spread of the disease.
Wallace and his students’ studies revealed that DDT did not kill just the beetles. Because DDT does not quickly degrade, poison remained on the elm leaves when they dropped in fall to become compost in the soil. Some of the DDT probably fell directly onto the soil during spraying or was washed onto it by rain.
Soil and compost were ingested by earthworms, and the worms were eaten by American Robins and other birds. The DDT concentrated in the tissues of the birds, so a little DDT in an earthworm became a lot in a robin eating dozens of earthworms in a day.
These results were rejected by some, who suggested no causal relationship with DDT, or that other toxins such as mercury used to control soil fungi were the cause of the birds’ deaths. Wallace was severely criticized by some of his scientific peers. There remains some controversy even to the present day, but most scientists now recognize that DDT and other insecticides pose significant risks to other living organisms.