If one of the first signs of summer is the swallows arriving, then seeing them line up on the telegraph wires before heading off is one of the signs that summer is over, and it’s time to sweep the chimneys and fill up the log shed.
Over the last few weeks, my local Facebook groups have been full of pictures of house martins and swallows behaving strangely – clustering on the sides of buildings, hiding huddled together under the eaves and flying in huge flocks along the roads. They are gathering strength and filling their bellies before heading off across the Channel for just one stage of their epic journey south.
Everyone is familiar with the amazing story of these seemingly fragile birds flying all the way to Southern Africa and back every year, but a lot more of our wildlife that migrates than people might realise.
A lot of our birds are migratory, but because our birds who fly south are replaced by birds from the north, it’s not always obvious. That blackbird on your bird table probably isn’t the one that was there in the summer, but could be from Russia or Scandinavia.
Lots of migrations are annual and predictable, but sometimes we get an ‘irruption’; an occasional influx. For example, every ten years or so, if there is a particularly hard winter in Scandinavia the waxwings will eat all the berries and need to migrate south to find new supplies in the UK. I have seen these filling a rowan tree, and it’s a beautiful sight; somehow reminiscent of a Japanese painting.
Some birds are ‘moult migrants’. Birds go through an annual moult when they lose their feathers, and some, like the shelducks, lose all their flight feathers. Before this happens, they fly to remote locations and islands so that they can moult well away from predators.
It’s not just birds: many of our insects also migrate. The Painted Lady butterfly is very common here in summer, but spends winter in North Africa where it goes to breed. Dolphins migrate, as do whales and many fish. Eels are famous for their journey over the whole Atlantic Ocean, from the nurseries in the Sargasso Sea to quiet rivers and creeks in the UK, where they spend 12 years growing before heading back out to sea to start the cycle all over again.
For a chance to see some of our migratory birds, Seaton Wetlands in East Devon is fantastic, accessible and varied, and the Fleet behind Chesil Beach often has some interesting visitors.
Human activities can impact migrations, and hunting of geese in the north, and songbirds around the Mediterranean, have caused big problems in the past. Thanks to international treaties, this is improving, but is still an issue. Birds don’t see international borders, and are true citizens of the world. Maybe we could learn something?