How and why do birds migrate? Martin Benadie explores the wonder of bird migration, looking at the different species you can expect to see in southern Africa, along with the ‘sky routes’ they take to get to our sunny shores.
Seasonal migration is where individuals move to and from geographically separated home ranges to exploit changes in environmental conditions and seasons. Why many bird species travel such immense distances to do this however always leaves me with a sense of wonder and amazement. Each year, billions of birds funnel from Europe and Asia into southern Africa and back again. Birds visiting southern Africa in the austral summer can number over 180 species and all typically follow the same migration routes. What is just staggering is that almost half of the 10,000 recorded bird species in the world migrate! It is estimated that 5 billion birds of at least 200 species migrate to sub-Saharan Africa.
These bird flyways into southern Africa can be grouped into two main routes:
Most intra-African migrants breed in southern Africa during the austral summer. Examples of common species in this group include red-chested cuckoo, African paradise-flycatcher and African pygmy kingfisher. Woodland kingfishers start moving from Central Africa in September down into southern Africa – their call a distinctive cue that they have arrived. The yellow-billed kite and Wahlberg’s eagle also undertake seasonal movements to breed. In March and April, Wahlberg’s eagles leave their breeding grounds in southern Africa’s woodlands and head north to as far as Sudan. The southern carmine bee-eater is another African migrant.
Woodland kingfisher – Photograph by Caroline Culbert
Palaearctic migrants do not breed in southern Africa. Their motivator to move is mostly to escape adverse weather conditions in their breeding grounds. The willow warbler is a tiny passerine that travels up to 12,000 km from Siberia to southern Africa. Amur falcons are delightful raptors that navigate up to 22,000 km each year along their vast migration route from Siberia through the Himalayas and all the way down to Somalia, Kenya and South Africa. Barn swallows are well-known visitors flying around 11,000 km between Europe and Asia to southern Africa. It is phenomenal to think that young barn swallows travelling from their nests in Britain to ‘winter’ in southern Africa face such a long journey, and that for a bird only weighing 20 grams! The mortality rate in juvenile barn swallows is as high as 80% though. Some other long-distance travellers include lesser kestrel, European honey buzzard and European bee-eater. Another interesting group of long-haul flyers are the waders (shorebirds). Red knots frequently move around 3000 km non-stop, often across open seas.
Southern Carmine bee-eaters in the Linyanti – Photograph by Russel Friedman
Birds on the Move: Under Threat
Migrating birds also unfortunately face many challenges on the way, with birds being heavily persecuted in certain areas. In Senegal alone it is thought that as many as 25 million birds are caught for the cage-bird trade. Birds are also slaughtered for food and traditional medicine. Conservation India estimates that between 120,000 and 140,000 Amur falcons are slaughtered every year in north-eastern India!
At the onset of summer in southern Africa look and listen for that first Diderick cuckoo or greater striped swallow and spare a thought at the great effort these migrants make each year in getting here. Over the centuries, man has always grappled to understand birds’ migrations. Perhaps humankind is not as sophisticated as they think.
Written by Martin Benadie, Guide and Copywriter at Wilderness Safaris