Pesticides are the more recent threat, but their numbers were hit pretty hard prior to DDT by hunting. Congress put a stop to that in the 40s. Farmers saw them as a threat to livestock.
Hunting... Eagles existed in such large numbers and predated on small lifestock. For 36 years, Alaska paid a bounty of $2 per dead eagle. They had a confirmed 120,195 eagles which bounty was paid on.