Which half-ounce bird travels the 4100km (2650 miles) twice a year between Britain and the Sahal Region of Africa?
It was my job as a young child in the early 1950s to scythe the stinging nettles from around our farm’s chicken coops. I used a hand scythe so I would not sting myself and I made sure there were dock leaves nearby just in case. On one occasion, I stumbled onto a nest, carefully strung between several nettle stems, and constructed of dead grasses and lined with horsehair. It contained three small eggs, greenish white and delicately spotted with ochreous brown. I checked my bird book to confirm the nest belonged to a whitethroat.
This is a small grey and brown warbler with a pure white throat that migrates between Britain and north Africa each year. It has an even smaller cousin – the lesser whitethroat – but this species is less common in Britain, more secretive and its eggs are whiter and more boldly patterned than the ones I saw. Although there are about 118 species of warbler in North America, neither of these varieties are represented. New World warblers travel as far north as Alaska for breeding and winter in northern South America and the West Indies.
I cried myself to sleep that night knowing that the adult birds would not return to their nest because of my disturbance. I was correct. Subsequently, when I saw whitethroats on exposed branches delivering their scratchy song with gusto, I wondered which of them might have lost their brood because of me. By September, most had dispersed south to Africa.
These birds begin their long migration south to the Sahel Region, just beyond the Sahara. The region stretches 3400 miles (5500km) from the Atlantic to the Red Sea. The journey can be as long as 3500 miles (6,000km) and takes several weeks to complete. They fly by night. The biggest challenge is to safely traverse the Sahara by finding tail winds at some altitude to help with the crossing and eating plenty of berries from the Salvadora bush before they start (easy to digest and rich in sugar).
Reading about whitethroats and their long migration introduced me to the geography of North Africa and in particular to those countries that belonged to the British Empire. Combined with stamp collecting, I learned about territories such as Ghana, Nigeria, Sierra Leone, the British Cameroons, Gambia Togoland, Uganda, the Sudan and Somalia that only became independent of Britain during the years 1957 to 1965.
It’s sad to admit that there are fewer whitethroats migrating in recent years because of the desertification of their winter habitat, caused by drought and over-farming. This was particularly serious back in the late 1960s when the numbers of whitethroats reaching Britain reduced by 70 percent. These days, about a million birds make it to Britain each year to breed, and the species are widespread migrants to other parts of Europe.
I owe it to the whitethroat and the migration of other birds to introduce me to world geography, that evebtually became one of my two degree subjects at university (the other subject was geology). Some other bird species that migrate incredible distances are as follows:
- Swallow (UK): travels to South Africa/Namibia, Arabia or India for winter covering 5,000 to 6,000 miles (8,000-10,000km) each way. It flies low during the day, does about 200 miles (300km) a day, and takes 6 weeks to travel.
- Arctic Tern (UK): has the longest migration of any bird, traveling as far as Antartica; covers 22,000 miles (35,000km) a year. The North America Arctic tern travels even further – 24,000 miles (40,000km) annually.
- Goldcrest (UK): this bird weighs only 0.2 ounces (5 grams) yet will migrate across the North Sea to Britain from northern Europe. It is one of the lightest birds to migrate and will stop half way for a rest, if need be on a fishing boat at sea.
- Bar-tailed godwit (US): migrates from Alaska to New Zealand without stopping; the 7,145 mile (11,500km) takes 9 days.
- Red knots (US): shore birds that nest in the High Arctic and migrate to the southern tip of South America, a journey of 9,000 miles (14,000km).
These are just a few examples of the many bird that migrate long distances each year to escape bad weather and find new sources of food.