Check any farms around they could have one of those air cannon that go off to spook geese and deer off the field. They are on a timer and build up pressure and then go off. There is one down from me and took a little bit to realise what it was.
Its Sunday shouldn't be any gun hunting going on. Yeah northern zone duck is open as well as squirrel, rabit, and crow. But no where on Sunday can you gun hunt unless its a farmer protecting livestock, or a trapper dispatching with a .22 short. Or **** at night possibly.