No, this is not a trick nor any act of neighbor vandalism. To anyone who doesn’t know the fact, this impression of an owl on the window would definitely look weird and otherworldly.

What looks like an incomplete image of a flying creature is actually a trace of an owl which accidentally collided with the glass pane at a home in Kendal, England. The figure complete with head, body and wings is in fact the powder down of the owl left behind after the impact. “Powder down is a special type of down feathers” which produces a dust like substance used by the birds to coat all external feathers. The dust in addition to waterproofing, keeping off parasites is useful to the birds in a number of ways.

If you are wondering about the owl then the resident did search for the bird but not finding it in the vicinity supposed  it to have flown away without any injury.

BBC