I read this is in a story and find it suspect.
I took a seminar a few months ago on Canada Geese management. My understanding is that geese do not stay scared off by decoys, whether their swans, coyotes or alligators. They might be wary and avoid them for a while, but they soon realize that it isn’t actually a threat.
If you’re talking about geese in the US during the summer*, when they would normally be up in Canada, it’s even tougher. Those geese usually have flightless goslings to protect, and don’t get scared off easily by anything, then they molt and can’t fly away even if they wanted to. Once the goslings are born, you’re generally stuck with the geese for a few months, no matter how many decoys or lasers or border collies you use to chase them away.
*These are geese people are generally annoyed with and want to chase away.
I’ve seen geese and swans close together in the same pond many times. Once I saw a flock of about 6 swans who lived in a harbour on the sea. There was a single white goose with them who evidently thought he or she was part of the gang.
Yeah, I doubted the idea because I’ve tried both bobble-head owl statues and rubber snakes to divert birds from my garden, to no effect. Spinning metal pinwheels do tend to keep them off the ledges.
This sort of identity/morphology mismatch leads many confused birds to undergo goose-change operations.
Friends of mine have a farm/orchard. Birds are very difficult to scare off. For a while they used air cannons that would periodically “BOOM”. Effective, but complaints from neighbors miles away lead to a switch to a less noisy system. Currently they have speakers broadcasting sounds of “bird distress” every few minutes. Not as effective as the cannons, but better than nothing.
I have a half dozen customers who aren’t fans of geese making their homes in their ponds. A few have tried decoys to no effect. One introduced a pair of swans and the geese don’t stick around anymore. The others do things like set up sprinklers around the pond or make a habit of chasing them off. Another way they deal with them is in the spring when the geese lay eggs the send a guy out to each nest and roll the eggs over. I’m not sure how that works. They said if the break them the geese lay new eggs but if they disturb them the geese don’t try again.
There are a lot of geese where I work.
Someone placed some life-sized cutouts of coyotes on the lawn where they congregate. The geese proceeded to poop around them.
This is called addling or oiling. Addling shakes up the interior so the egg cannot hatch, oiling is coating the egg with corn oil so it can’t get oxygen and won’t hatch. When you don’t break or remove the eggs, the geese still think they’re viable and don’t lay any more.
Since these eggs never become goslings, the geese don’t have anything to protect, and can be successfully chased away before they molt. Decoys still don’t work, though.