It took a full side run into the window. Luckily we were right there and I ran out to rescue it (it did a face plant into the grass below and had its little heinie sticking up into the air) before dh came along with the lawnmower. I put it in the shade in a protected area.
Last I checked, it seems to have perked up. I hope it's flown off by now.
"To be conscious that you are ignorant is a great step to knowledge." ~ Benjamin Disraeli (1804 - 1881)