...by cedar waxwings! 
It's the time of year that these birds swarm the neighbourhood in search of berries, and they happen to really like the mountain ash in our front yard. Right now there are hundreds of birds flying from tree to tree around my property. Apparently they get drunk from eating the fermented berries, and have trouble navigating...I think a bird has hit every window of my house so far. At this point, there don't seem to be any casualties.
It's the time of year that these birds swarm the neighbourhood in search of berries, and they happen to really like the mountain ash in our front yard. Right now there are hundreds of birds flying from tree to tree around my property. Apparently they get drunk from eating the fermented berries, and have trouble navigating...I think a bird has hit every window of my house so far. At this point, there don't seem to be any casualties.
Luckily, the birds can't do much to hurt the windows, it's just disconcerting to hear a thud every few minutes. I'm hoping that we don't see any injured birds on the ground this year. So far so good...it seems the flock has moved on now...will probably see them back in a day or two.