Is it UFO? or just a bird?

This is an old photo which was taken by my wife on our trip. I'm sure there's nothing in the sky when taking the photo, but after we opened this photo on the computer, I found an unusual spot in this photo, then I zoomed in the picture…… my god, it looks like a flying hat!

Is it a bird??

My wife remembers she totally took 3 photos within 2-3 seconds, there's nothing at the same place in the first and third photo, it means the speed of this 'flying hat' is very high, so I don't think it's a bird.

Or UFO?

Now, I'm finding the original size of this photo on my old computer, I will upload the big version of this photo to Dropbox and copy the share link here later.

If you are interested in this mystery, please stay tuned!! I will be back on this topic!!