Jackie... you were closer... but not quite there.
Steve nailed it... it's a "bird print", left over from a bird that had managed to slip down my chimney, ended up in the fireplace (getting covered with ashes of course) then flew out of the fireplace and aimed for the first "outside" he could see... Which unfortunately is on the other side of the living room window.
Despite having chimney caps, birds frequently find their way down my chimney and end up trapped behind the glass fireplace doors. As soon as I open the doors to free to bird, they (almost always) immediately fly into a window... leaving a lovely ash bird print... and I grab whatever towel is handy to toss over the bird so I can scoop him up and take him back outside. If he hits the window hard enough to knock himself silly, R takes over and nurses him until he recovers enough to have a fighting chance out outside... (She's pretty good at it, she hasn't lost one yet!)
We don't get birds down the chimney all the time, but it happens often enough during warm weather that my windows often have bird prints on them.
Here's an old picture (a year or two ago) of one of the birds that we've had to catch and toss back outside.
Good job Steve.... I wonder if it was easier for your artist's eye to see the image of the bird in the ashes on my window (or maybe you just have birds flying into your windows and leaving prints too!)
I'll close with a few pictures I took today...
Deer crowded around the back fence, eagerly eating last fall's dry cottonwood leaves (the bench was knocked over by the wind today... it was fierce and blew just about all day!).
Sunset colored clouds through the trees...