BOISE, Idaho - Bald eagle populations surged in the northeastern United States and remained steady in other areas during the past 15 years, according to an analysis released by the U.S. Geological Survey.
Across most of the lower 48 states, bald eagles increased nearly 2 percent annually from 1986-2000. The analysis was based on more than 10,000 eagle sightings during mid-winter surveys in 42 states.
Results of 15 years of the Midwinter Bald Eagle Survey, which involves several hundred scientists and trained volunteers who count eagles from land, water and air, have just been published by the federal agency and Boise State University scientists.
"Eagles are one of the great success stories of the Endangered Species Act," said Tom France, director of the Northern Rockies office of the National Wildlife Foundation. "With the protections we have given them and their habitat, they'll soon be ready for delisting."
In the middle of the last century, populations declined dramatically due to the accumulation of the pesticide DDT in fish, a staple of the eagle's diet. The pesticides gradually poisoned adult birds and caused females to produce thin-shelled eggs that broke easily, destroying the embryo.
The National Wildlife Federation started the annual survey in 1979, a year after the bald eagle was listed as an endangered species in 43 states. In 1995, the bald eagle had recovered enough to be reclassified as "threatened." Proposals are pending to remove the bird from the list entirely.
During the study period, eagle numbers increased an average of 6.1 percent in the Northeast; 1.5 percent in the Southwest, and 1.1 percent in the Northwest. The Southwest declined by 0.7 percent.
Scientists are unsure why there was such a dramatic increase in the Northeast.
"We can only speculate," said Karen Steenhof, survey coordinator and a research scientist at the USGS Forest and Rangeland Ecosystem Science Center. "It might be the increasingly warmer winters, which meant more open water," allowing the fish-hunting birds more access to prey.
Juneau Empire ©2014. All Rights Reserved.