I let a pair nest on my island, then I came home to a party that they were throwing and they invited about 40 relatives. The following year I had an explosion of Eurasian Water Milfoil in the pond. From then on I had to battle it, even when using Sonar A.S. every other year.
I have since learned that a SINGLE goose can pool enough fertilizer in the pond EVERY DAY to grow 115# of algae......
I have a permanent NO VACANCY sign out now on the island.