steph19 wrote:
I have a feeling that they have managed to get under the shingles/into the attic, as they head into a corner (kind of like pictured above) and then disappear.
No doubt they live close by.
Like in this beautiful Heathwood neighbourhood.

Or this Mattamy master bathroom vent - that's missing the required screen.
Oh well !! what' s a little debris, a copious quantity of sticks, dead insects, piles of bird poop, and a dead baby bird or two going to do anyways in that exhaust duct? It's much much better just to pay someone a heap of money later to remove all that crap then to have that new home inspected.
