There's usually a logical explanation for anything odd .... it just takes some time to work it out.
For the last year or two I've been intrigued by a pair of mallards (
Anas platyrhynchos) regularly seen waddling around the Sheffield University grounds - particularly the main car park and outside the Students Union. Why - were the students feeding them (with all those loans to think about)? To the best of my knowledge it was some distance from any water.
However, today, walking through Weston Park (which houses Sheffield's Museum, one of the Art Galleries and parts of the University), voila! A pond that wasn't there the last time I looked!
I could have photographed the ducks but I was more taken by the rays of sunshine sloping through the trees!