By Chris Volonte
Moving through New England in a wave each fall is a petite predator that might be one of the most frequently overlooked birds in Massachusetts. Measuring 8 inches long and weighing less than two tennis balls, northern saw-whet owls breed in southern Canada and the northern U.S., and at high elevations such as the Appalachians. They have large gnomelike heads, big eyes, soft feathers and a tendency to sit tamely when a person is near. They’re nocturnal, inconspicuous and — if you’re lucky enough to see one up close — impossibly cute.