DDT, a persistent organochlorine insecticide, accumulated in the tissues of bald eagles and other birds of prey through the food chain. As the birds ingested contaminated prey, the DDT became concentrated in their bodies, ultimately affecting their reproductive success. One of the most significant impacts of DDT on bald eagles was the thinning of eggshells. This occurred because DDT interfered with the metabolism of calcium, a crucial mineral for eggshell formation. As a result, the shells became thinner and more susceptible to breakage during incubation, leading to reduced hatching success and population declines.
Reduced immune function: DDT also affected the immune systems of bald eagles, making them more susceptible to diseases and infections. This further contributed to the decline of their populations.
Disruption of hormone regulation: DDT can mimic the effects of estrogen, a female sex hormone. This can disrupt the normal hormone balance in both male and female bald eagles, leading to reproductive problems, abnormal development, and behavioral changes.
The buildup of DDT in adult bald eagles had far-reaching consequences, not only for the species' reproductive success and survival but also for the entire ecosystem. The banning of DDT and the subsequent reduction of its use in many countries played a critical role in the recovery of bald eagle populations.