Not sure why, but the fallings limbs have been a problem this past year. It may be somehow related to the drought we have had, not sure.
I have been staying under hemlocks lately if possble - I try to find one that is not appears to have safe trees around it. There just never seems to be a lot of fallen branches under hemlocks - the limbs of the hemlock must help to divert falling limbs from other trees.
I found this sweet site about 3 weeks ago - there was a wishbone shaped, large limb hanging in the hemlock, so I found a long dead limb and began whacking at it - and I'll be danged if that wishbone didn't jump right off its perch and try to impale me. But once cleared out the hemlock gave me peice of mind and I slept well that night.