the British population of the Grey Heron does not migrate as such- it tends to disperse widely around the British Isles post breeding. In Europe Grey Herons tend to move south and west during the winter, returning to eastern european countries in the spring
Got lots of them where I live (North Wales) and until last week I thought they only ate fish until I saw two of them on the golf course and they were stamping on the ground to make the worms come up, never stop learning do we.
Then there are the heron species that frequent the other side of the world. Some are endemic to Australia and don't move at all. Some migrate only a few hundred miles but do so very gradually.
sorry, should have been more specific. as we now live in chicago, on a lake by us there were both grey and white herons till last week, that why i wondered if they migrate as its getting quite cold here now. going to be minus 7 for a few days this week during the daytime! also wondered about the geese we have here. as we are quite close to canada, will these geese leave for warmer climes too do you think?
Any aquatic or wading bird is going to have to move somewhere else if all the open water surfaces become totally frozen over in winter. It's that, or starve.
you have a few more heron types than we do in europe! Herons in the US are partially migrate depending on location- much like Europe. From Michigan the Great Blue and Green Herons go south for the winter- for example the populations in Washington state remain all year round generally. The Cattle and Great White Egrets do a similair thing. As regards geese- many migrate but it is human activity that allows some to winter around Lake Michigan- feeding on winter wheat and finding food and water put out by humans. Lake Michigan is fantastic in the winter when the waves freeze onto the shore- but it beats me how any bird survives the intense cold!!