Migration is a fascinating topic
[The Namibian – September 2010]

Migration is a fascinating topic that has posed research questions for decades. Although the how,where, when and why of navigation and routing continues to interest scientists, a newer urgent question concerning the effects of climate change on biodiversity and animal migration must be addressed. In both celebration of and concern for all things living, 2010 has been declared the “International Year of Biodiversity” by the United Nations. The Ministry of Environment and Tourism, as custodians of our natural environment, has through their Directorate of Environmental Affairs invited and supported the development of local resource materials to enhance awareness of our unique Namibian heritage, our biodiversity.

Birds are wildlife that can be seen by almost everyone every day. Because migrant bird species move across the globe, they can be seen as ambassadors for the world’s biodiversity and for our responsibility to reduce threats to life on earth. NARREC (Namibia Animal Rehabilitation, Research and Education Centre) has produced a poster on migrant birds and their migration routes to and from Namibia. These routes are both within Africa, intra-continental as well as from Europe and Asia, inter-continental. The poster also highlights the threats to biodiversity, climate change, pollution and habitat alteration. These negative actions and events together with other inappropriate human behaviour occur globally and threaten a wide variety of flora and fauna. Migrant bird species are vulnerable to poor land management and unethical behaviour over many lands as twice a year they move on their north-south routes through countries and across continents.

Migrant birds also highlight a southern hemisphere celebration, the arrival of spring and the promise of rains to come. The basic pattern of bird migration throughout the continents is between northern breeding grounds and southern “wintering” grounds. Birds leave the increasingly cold weather and shortening daylight hours in the north to use the summertime food abundance in the southern hemisphere. Birds use a range of aids to navigate across 1000’s of kilometres. Although most birds take a general route, a number of birds use “fly-ways”. For example large birds of prey that rely on soaring rather than flapping to fly need thermals to reach their destination. Thermals are up-draughts of warm air found over land, and large migrant bird species have specific migration routes that avoid crossing large tracts of water when entering or leaving Africa.

Most bird species travel more or less on time, arriving in Namibia from late September through to November and leaving again from March through April. Some birds migrate close to the earth and others up to 2 kilometres high. Besides their physiological and genetic direction finders, the birds use mountains, rivers, coastlines, the sun, the stars and the winds to navigate. Before leaving on migration birds pack on fat, some even double their weight even though all do need to stop and feed en-route. From Asia, eastern, central and western Europe, northern and central Africa to and from southern Africa, migrant birds move to follow a summer bounty.

Although Namibia and Africa does not have the bird that holds the record for the smallest of migrants, a 3 gram American hummingbird species that flies around 3 200 kilometres a year, we do see the Arctic Tern which holds the world’s distance record. For decades the Arctic Tern has been recognized as the most spectacular of all the migrating birds. Weighing only 100-120 grams, this tern never takes the shortest route between its northern breeding grounds and the Antarctic Circle, its southern summer destination. Seemingly fantastic distances like 35 000 kilometres a year were written about until recently when a satellite tracked Arctic Tern logged 70 900 kilometres in a single year.

NIED the National Institute for Educational Development will distribute 7000 posters to schools in the thirteen regions. Other distribution will be given to the Ministry of Youth. Anybody interested in acquiring posters can contact NARREC

Liz Komen