Re Toby's comment - actually we know a lot about where the Brent Geese come from and where they go to, as many of them are colour ringed. They are part of the population which winters in Ireland, which is where they are ringed. Some of the geese whcih pass through the Cleddau actually winter in France. See the Avifauna entry here: https://pembsavifauna.co.uk/category/brent-goose/
