Maine's bald eagle population appeared to make a modest gain in 1980, but researchers still fear for the birds' survival. The University of Maine's eagle protection project reported that Maine eagles reared 40 young during the past year -- two more than the number reared in 1979. The National Wildlife Federation, which surveys the nation's bald eagle population, counted 115 of the birds in Maine earlier in the year. Bald eagles have been on the federal government's list of endangered species since 1978. Nearly all the 200 bald eagles known to be living in the Northeast now live around Cobscook Bay.