The greatest threat to the bald eagle is no longer pesticides, but development and suburban sprawl, say environmental scientists. The bald eagle has starred in one of the most successful species-restoration stories in U.S. history; thanks to the banning of DDT in 1972 and the careful efforts of environmental advocates, the eagle has soared back from the brink of extinction. Still, bald eagle populations have generally risen fastest in states with the lowest rates of population growth. The growth in numbers of vacation and second homes has put pressure on the birds throughout the Northeast. “Loss of habitat is the biggest threat facing eagles right now,” said Karen Steenhof, a biologist with the U.S. Geological Survey and an eagle-survey coordinator.