Alexis noticed this dead barred owl, and then told me about it. Here's my picture, and hers is
here.
Barred owls, Strix varia, are rare enough in Boston that a sighting will buzz through the birding community, and dray a binocular-wielding crowd to find and see it. But they are fairly common in the near suburbs, breaking the calm of night with their surprisingly loud and high-pitched hoo-hoo HOOAHH!! In the Boston area they may eat any number of small animals: rats, mice, bats, flying squirrels, and even smaller owls. In southern places and swampy areas they'll eat frogs, lizards, and snakes. They are less shy of humans than their close relatives the spotted owls. This, along with the spotted owl's more demanding habitat needs means that barred owls are expanding into former spotted owl territory and displacing them.
There are few clues to tell what killed this owl. It's too decomposed to be sure, but its limbs are intact, making predation a less likely explanation than illness or starvation.