It is a fact that the vast majority of birds migrate, and that only a minority are sedentary. In extreme cases, such as the famous Arctic tern, a bird may travel up to 44,000 miles in a single year for the sole purpose of migration. This bird, which in 1982 was ringed as an unfledged chick in Northumberland in the summer, was found in Australia in October that same year, which means it must have travelled a distance of 14,000 miles, assuming a direct route. This staggering distance is certainly humbling, and the Arctic tern most definitely deserves its reputation as a wonderful curiosity of nature.
But closer to home we shall look. Here, we have our own wonders of the avian world, many of which partake in the annual migratory movement from places such as Africa and northern Europe. What is often a surprise to many people is that some bird species have migratory variants and domestic variants. Take the Blackbird, for instance; this seemingly very common bird is domestic all year round in the UK, but numbers can swell to huge proportions over the winter when visitors from all over Europe come to the UK. On the other hand, while we have visitors coming to the UK, many of our own summer species leave for warmer climates because of a scarcity of insects and other invertebrates in the ground. In fact, roughly half of UK birds migrate at some point over the winter period.
Migratory species fall into three broad groups. The first are known as irruptions, or sudden arrivals in large numbers. Our All About feature on page xx discusses the Waxwing, a bird that is famous for arriving in irruptions. The second are known as altitudinal migrants, or, in easier terms, birds that migrate only “up or down”; an example of this would be a bird arriving from Scandinavia to escape the severe cold. They would migrate south in winter and then north in summer. The third type are known as moulting migrants; some birds are at risk when they lose their flight feathers due to moulting, so it’s better, from a selective perspective, to find a location where moulting can be done safely, away from the prying eyes of dangerous predators.
Many migrants from places such as Africa will be leaving us shortly. In a dream journey for many of us, they will leave the UK and travel towards South Africa, passing such places as the Nile Valley, perhaps capturing a glimpse of the Pyramids from high above; or even moving across Tanzania and taking a break on Mt. Kilimanjaro, before soaring above Olduvai Gorge, the seat of humanity.
On the other side, you can expect partial migrants such as Blackbirds, Robins and Chaffinches to arrive and complement the existing populations of similar domestic varieties; this, of course, often depends on the severity of winter in eastern Europe, so it’s a good idea to keep an eye out and provide additional energy-rich food for these birds, especially you notice greater numbers of these birds in your garden.
More permanent winter visitors include those migrants from northern and eastern Scandinavian countries, coming here for the far milder weather and easier pickings of food. These birds include Fieldfares, Redwings, Bramblings and many kinds of ducks and geese.
As always, it’s useful to be on the lookout for, and even make notes of, any interesting migrants you may see. Put out food, as arguably their main purpose, aside from a warmer environment, is to discover a new source of sustenance. Don’t forget, some of these birds travel far, and there’s nothing better than a hearty meal at the end of a long journey.