In contrast to the large populations of the past, the unregulated use of pesticides, such as DDT, and the loss of uncontaminated waterways and habitat, caused the eagle to be placed on the endangered list but the focus on a cleaner environment has begun to pay off. Once these transported birds were raised to adulthood in their new homes their instincts caused them to return to the same nesting sites and thus the beginning of a new population of Bald Eagles in Pennsylvania. Recent surveys have recorded record numbers of Bald Eagles in Pennsylvania including areas along the Allegheny River. The exciting increase in the eagle population makes it more likely for visitors to get the chance to view this awesome bird. Visitors may want to keep an eye out for nests.
Eagles return to the same nesting site every year and add on to the original structure each season.
The largest nest ever recorded was 9 feet wide and 20 feet high.