This happened a couple of years ago at my cousins' house in Cape Breton, Nova Scotia.
My aunt was at work, and the only people in the house were myself, my sister, mother, and youngest cousin.
We were playing Monopoly on the far side of the living room, on the floor, when we heard this really strange sound, like a parrot was cawing or something along those lines. We all looked at each other, and were really freaked out, because it was Nova Scotia; generally, there are no tropic birds in the area, and that's distinctly what we heard.
My cousin and I were quite scared and of course, we hid behind the chair. Naturally.
When my aunt came home from work we told her what we had heard. Now she told us, quite matter of factly, that when they bought the house from it's original owners, about 15 years before, that they had a bird, and it's stand was in the same spot we'd heard the noise coming from.
Needless to say I found it quite creepy, and still do, though really the experience wasn't that scary.