An owl apparently crashed into the window of Sally Arnold's home in Kendal, England, leaving this image. Experts said the silhouette was left by the bird's "powder down" - a substance protecting growing feathers. Here is a selection of photos sent in by you of various bird imprints.

Ann Colgan: "I was upstairs when I heard an almighty crash. I found this imprint on the bedroom window. I subsequently found the pigeon on the patio, under the window, it appeared to have broken its neck." Taken in Holyport, Berkshire.

Paul Thomas: "We had heard a 'thump' during the night but had not found anything out of place or unusual the next morning. It was not until a few days later when my daughter came round that we saw the imprint." Taken in Sanderstead, Surrey.

Charlie Wilson: " I was in the room at the time with my curtains closed and the sound of the bird hitting the glass frightened the life out of me!" Taken in Guildford, Surrey.

Barbara Mellor: "A seagull hit the bedroom window of my bungalow with a tremendous thud which set my dog off barking. I was amazed not to find a dead seagull outside on the path. It must have flown off - I would think with a dreadful headache!" Taken in Budleigh Salterton, Devon.

David Morton: "We recognised the imprint straight away as a tawny owl and as in the Kendal incident, the bird appears to have been uninjured." Photo taken by Sally Morton, near Ross-on-Wye in Herefordshire.

Mladen Radman: "This was the second time I encountered a bird's imprint on the window but the first time I had a camera to hand. There is an eerie beauty in the ghost like image." Taken in Edwalton, Nottingham.

Robert Baxter: "I noticed the imprint when it was illuminated by patio lights that evening, and was surprised by the detail, including an imprint of the bird's eye." Taken in Chafford Hundred, Essex.

Chris Dew: "When I stayed in Keswick for a wedding in July 2010 we returned to our room to see the perfect imprint of a duck on our window." Taken in the Lake District.

Kate Schreiber said her father-in-law saw an owl print on his bedroom window in Effingham, Surrey. "The owl crashed into the window during the middle of the night, he heard an almighty thud and got up to investigate but of course there was nothing to be seen until the next morning.," she said.

Barry Howard: "Imprint of pigeon after collision with patio door. We have at least one bird strike against a window each year and it's always a pigeon. There's such a loud bang it's surprising they manage to fly away but they do." Taken in Mudeford, Dorset.

Mike Neal: "We came home and saw this imprint on the patio window, I believe it is a Sparrow hawk. Obviously I was very concerned about the safety of the bird, but fortunately it was no where to be seen so I guess that it flew off safely." Taken in Bedfordshire.

Ian Watson: "This picture was taken at my sister's house in Attleborough in Norfolk, UK. You can see a collared dove outline on the window."