I've heard that ducks will eat fish from a pond. Is this true? I have a small pond with goldfish and I don't want them to eat the goldfish. Do ducks HAVE to have a water source? If so, how much is enough for a couple of ducks? Also, is there a breed that won't fly away? I'd hate to get some, get attached and then have them leave. Will they go in with my chickens at night? What type of food do they eat? Do they winter well? How would I keep my cat and the neighbors cats & dogs from getting them? TIA!