Wings have given the great skies of our Earth to the birds. In their many shapes and patterns birds curl and float exorbitantly like clouds, sifting and sliding aerially, tumbling and streaking high up against the blues and puffy whites.
But for many species the drift is purposeful and obligate and directional. For these birds, the airways have become great routes across our horizons, linking habitats intercontinentally.
Bird migration is one of nature’s most enigmatic and mysterious phenomena. It’s a story of great distances, perilous journeys, endurance and awe-inspiring precision. It’s a story linked intimately to the changing seasons, of trees with falling leaves of auburn, changing carpets of flowers and melting ice. It’s a story of a celebration of the powerful, dynamic forces that have shaped our landscapes.
Over geological time, over millions of years as the patterns of the continents changed and climates shifted, birds have responded by travelling, flying in search of food and breeding grounds, becoming part of the ebb and flow of the climate and connecting to the cycles of a spinning planet.
Some migrations are very short – the movement of a few hundred metres down a mountain slope, a subtle drop in altitude, like that taken by the Cape rock-jumper, a species found only in the southern parts of our country. Others are very long. Think of the epic circumnavigations of the globe undertaken by such species as the Arctic tern which nests in the far north during the Arctic summer, starting to fly south as early as August, following the African coastline to reach the Antarctic by November and then drifting with the winds that blow east, enjoying months in the deep, low latitudes before retracing its flight all the way home.
Migration is really about being in the right place at the right time. For this reason, birds have two body clocks built into their physiology to give them good circannual (yearly) and circadian (daily) rhythms.
Environmental stimuli activate their hormonal systems, which causes fattening, moult and restlessness, and then the air seems to call them to the sky.
For many local birdwatchers the South African summer is a time of exciting arrival. With the lengthening of days, warming of nights, busyness of sounds, there’s a frenetic buzz of life and our wilderness seems to explode into a vivid dance, feathered in carnival displays of avian migratory abundance as birds appear everywhere.
From the tiny willow warbler (weighing between seven and 12 grams) from western Europe to the bright white stork (weighing up to four kilograms), also from the north, we witness a diversity of birds arriving annually, some descending in their millions.
This tremendous wealth of species is an affirmation of the interconnectedness of the global environment, of its indifference to political borders and its overarching power as an ancient interdependent system. And as the birds start to decrease in number or alter their patterns – phenomena of recent times – it’s also a very real reminder of a world in dangerous flux and pending irreversible change.
Become a member of BirdLife and become part of conservation
By watching migratory birds and recording their movements and numbers, the citizen scientists who belong to BirdLife South Africa and work with the Animal Demography Unit of the University of Cape Town are using their birding skills to take part in very important data-capturing work called atlassing. Use your hobby to become part of conservation – find out more about becoming a member at www.birdlife.org.za.
