I think the birds in question may be a barred owl. We live in a wooded section of Tuftonboro and were startled the other night by a night-long hissing/rasping call of two birds. At 2AM, curiousity got the better of me and I searched the wood margin (from my rear slider) with a flashlight.
Two barred owls popped into view. Upon further daylight research on the internet, many web-sites describe very varied vocalizations including screaming, coacking, rasping, wheezing, etc. We always assume they only make the usual "Who cooks for me" sound. Since the week before we had a bear on our front porch at 4:30 AM , seeing just owls was a great relief.
