Many geese/ducks/etc. are NOT safe on ponds at night - it's their only choice of location in the wild but it is not safe. Bobcats, coyotes etc. can all swim and jump in on a goose/duck. Happens all the time - happened to our neighbors recently and 2 geese were drowned and eaten on the bank.
So, IMHO sitting on the side of a pond at night is a "sitting duck" waiting for a predator. Haven't you seen National Geographic where predators go to the watering holes at night/day to sneak up on their prey....
Do you have a barn or antyhing you can put them in at night that isn't too HOT so they are safe that is predator proof? It has to have air and ventilation and shelter from rain/etc. but not be too smothering/hot so they can move around and have plenty of room??
Some people leave theirs out and just get new geese/ducks when they are eaten or attacked. Not very caring, not very smart people.