Had a similar problem couple of times in the past, my ducks & geese quit entering the pond; they would just stand near the edge, or go in for a (very) quick dip, then return to land.....
Once a large turtle was nibbling on duckling legs, and two other times alligators had chosen to set up house and dine on the locals.
Hope this isn't your problem-
last gator (a 6 footer), had cut the population almost in half before Animal Control was able to capture it.
Edited by D. Roy (01/11/13 02:08 AM)