You may think that you're seeing more birds around your WildSquare than usual, and you'd be right. The blackbird is one of Britain's commonest garden birds and the chances are you'll see one when you do your survey. Many blackbirds are local and will stay in the same area all their lives. However in the winter blackbird populations are increased by the arrival of more blackbirds from colder places such as Russia, Eastern and Central Europe. So the blackbird you see in your garden may have flown thousands of miles to get there. The same goes for ducks and black headed gulls, some of the ones you see may have flown in from Moscow, Berlin, Stockholm or other areas around the Baltic Sea. They all fly over here in the winter because the climate is milder here than it is where they normally live. This is because Britain and Ireland are warmed by something called the gulf current.
You can't tell the difference between native birds that live here all year round and others that have just flown in, so how do we know it happens? It's all down to bird ringing. Scientists and conservationists catch birds and put small rings on thier legs with an identification number on it. They record where the bird was found and details about it's weight and condition. Later on other scientists in other countries will catch birds to ring them. If they find any that already have rings they will make a note of their ID number and look through the records to find out where that bird was first ringed and how many other times it has been caught. Scientists have been doing this for many years all over the world and in this way have been able to build up a fascinating picuture of the behaviour and migration routes of lots of different bird species.