Ddt was harmful to birds because it prevented them from laying eggs. true or false

True.
DDT and its metabolite DDE alter hormones, that affect calcium metabolism and can impact reproduction and development of exposed animals. Birds were major victims of the chemicals' effects. They experience reproductive failure as their eggs lacked sufficient calcium, were extremely thin, and shells broke when sat upon by the nesting adult birds. DDT and its metabolites accumulated to the greatest extent in raptors (that is, carnivorous birds that hunt and kill other animals), birds that eat carrion (that is, dead animals) and fish-eating birds. There were drastic declines in populations of these birds that feed at the tops of food chains. Many carnivorous birds (for example, bald eagles, ospreys, and pelicans) were on the brink of extinction before action was taken at the federal level to ban the use of DDT—and eventually other chlorinated hydrocarbons.