A Safe Haven

The duck shooting season is about to start and wild ducks are arriving at our town's well-named Sanctuary Ponds. How do they know?
Extra:  The crabapple tree had a bumper crop this year. There's a limit to the amount of crabapple jelly one can make and the rest of the fruit is being enjoyed by birds in the tree and on the ground. Lots had to be raked up before I mowed the orchard.