I have seen Bald Eagle(s) on the following dates during April:
4/3 1 adult
4/11 1 juvenile (likely 2010 bird)
4/12 2 adults perched a hundred feet away
4/21 1 adult
4/26 1 adult
The possibility of a pair either nesting or prospecting in the area must be considered. There plenty of bodies of water nearby including to support a pair; Round Meadow Pond, Wyman's Pond, Wachusett Lake (not the Res.), Mare Meadow Reservoir, Bickford Pond, NoTown Reservoir...to name a few. BTW, many of the lakes and reservoirs were formed many years ago to "feed" the paper mills in Fitchburg.