What made this loud call in the Hockomock Swamp in Massachusetts?

While looking around I found this video with a pair of intrepid photogs visiting the paranormal hotspot, Hockomock Swamp in Massachusetts. This area was dubbed the Bridgewater Triangle by Loren Coleman and it has had many Bigfoot, UFO, ghost, and thunderbird sightings in the area. While they were recording, they managed to spook themselves pretty well and ran in terror when some loud calls started. I've tried figuring it out and I'm stumped. Anybody familiar with the wildlife of Massachusetts want to help them identify the noise they heard?