The title is a quote from Aristotle and is difficult to dispute. His other proclamation on swallows, that they spend the winter in the mud of ponds, is plainly absurd. Bird migration is one area in which the reality is more fascinating and remarkable than the myth. Science, rather than reducing romantic notions to mundane facts is proving that bird migration is more amazing than we’d ever dreamt possible. But how can talk of migrant birds from Africa be relevant in the middle of winter?
The answer to the last question is that while we may think of February as winter, to birds and other wildlife we are well into spring. Indeed, warm fronts on 7th February 2004 saw a scattering of swallows as well as small groups of house martins and even the odd yellow wagtail on the south coast of England, a good two months earlier than usual! This was an extreme event but it was only an outlier of a general trend towards many of our migrants arriving earlier. A study in Guernsey (Sparks, 2007) showed that the mean arrival dates of many of our sub-Saharan migrants has shifted substantially between the periods of 1903-1945 and recent years of 1985-2005. In the latter period swallows arrived 16 days, wheatears and willow warblers 18 days, house martins 27 days and sand martins an incredible 36 days earlier.
“None though are as celebrated as the cuckoo, which for over a century has prompted a letter to the editor of The Times.”
Some of our migrants are greeted with great fanfare whilst some slip into the country without causing much of a stir. The first returnees such as sand martins, wheatears and chiffchaffs are probably only noticed by the keener birdwatcher. Swallows, house martins and swifts on the other hand are familiar birds and are eagerly anticipated. None though are as celebrated as the cuckoo, which for over a century has prompted a letter to the editor of The Times. The promise of warmer weather is probably the primary reason we look forward to the return of these birds so much.
It’s always interesting to see what sparks a welcome in other countries and perverse to think that in Iceland the birds that are eagerly anticipated are those that spend the winter with us. Pink-footed goose, whooper swan and redwing are seen as signs of spring there. The golden plover is said to arrive in Iceland to push away the snow. In Lithuania it’s starlings that are celebrated as the herald of spring. Nestboxes are made ready for their arrival , the swirling masses that entertain us throughout the winter at iconic roosts on piers and bridges hail from there, the low countries and even as far as Russia!
“A swift was tracked from Liberia to England in only five days, averaging 25mph over its 3000 mile journey.”
As mentioned earlier, science continues to inform us of the wonders of migration. Ringing studies have shown just how far birds go and have revealed interesting movements of birds that were previously thought of as sedentary, such as starlings, robins and blackbirds. Rather than relying on the chance recapture of birds that were previously marked, cutting-edge technology is now telling the story. Data loggers and satellite tracking systems are becoming forever smaller and lightweight and are now being fitted to the slightest of songbirds and revealing remarkable insights.
The British Trust for Ornithology has been tracking the fortunes of cuckoos on their migration from here to Africa and back and keeping us all updated with the latest news. A swift was tracked from Liberia to England in only five days, averaging 25mph over its 3000 mile journey. Undoubtedly the most incredible feat though was performed by a bar-tailed godwit. These waders breed right across the high Arctic, some spend the winter in Britain or pass through on the way to and from the tundra. One bird, with the rather unromantic moniker of E7, was tracked travelling from Alaska to New Zealand. A distance of 7145 miles, that was achieved at an average speed of nearly 35 miles per hour on a non-stop flight of a little over 8 days!
Social media is another modern advance which is helping us to track our migrant birds. As I write, with snow swirling outside the window, an old acquaintance on Twitter is reporting swallows streaming north over his adopted home in Tanzania. So give a thought on this February morning to our harbingers of spring. They are already on their way!
- Peter Brash is a wildlife and countryside advisor for the National Trust. He specialises in animal ecology; specifically birds, insects and bats. As well as the surveying of habitats, wildlife interpretation and engagement.
- The Weekly Witter is a new regular Monday morning mouthpiece for our many specialists to talk about what’s on their minds at the moment.