we have black swans and egyptian geese on my parents lake also wild giant canada geese. Nothing else can handle egyptians. My parents really want black necked swans and have a place to get a pair. I don't think its a good idea. The black swans are good they are peaceful as long as nothing bugs them and will put geese in their place. But I don't know black necks that welll arent they smaller than giant canada geese? Would they get bullied?