Birds are the most mobile organisms on the planet. Their ability to fly vast distances enables them to exploit predictable, short-term peaks in food availability. Almost one-fifth of all birds undertakes regular movements, usually tied to seasonal cycles. However, such large-scale movements also incur risks from commuting across the landscape. The balance between these costs and benefits determines who stays and who migrates. Recent studies suggest that migration promotes speciation, principally through the formation of sedentary daughter species. Here we highlight some examples and speculate how rapid global change might affect this process.
Migration has long fascinated people and considerable effort has been devoted to learning how birds migrate. We marvel at the physiological adaptations that enable Bar-tailed Godwits to fly nonstop for eight days from Alaska to New Zealand without eating or drinking. We have determined the range of cues that birds use to navigate to return to the same breeding and wintering sites year after year. We have demonstrated that the migratory urge is inherited, with genes coding for the direction and duration of migration. However, we know that the risk of being blown off course during a young bird’s initial migration can be greatly reduced by travelling with more experienced individuals and we have even used small planes to establish new migration routes for threatened species. But why do birds migrate in the first place?
この記事は African Birdlife の November/December 2021 版に掲載されています。
7 日間の Magzter GOLD 無料トライアルを開始して、何千もの厳選されたプレミアム ストーリー、9,000 以上の雑誌や新聞にアクセスしてください。
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この記事は African Birdlife の November/December 2021 版に掲載されています。
7 日間の Magzter GOLD 無料トライアルを開始して、何千もの厳選されたプレミアム ストーリー、9,000 以上の雑誌や新聞にアクセスしてください。
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Keith Barnes, co-author of the new Field Guide to Birds of Greater Southern Africa, chats about the long-neglected birding regions just north of the Kunene and Zambezi, getting back to watching birds and the vulture that changed his life.
footloose IN FYNBOS
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CAPE crusade
The Cape Bird Club/City of Cape Town Birding Big Year Challenge
water & WINGS
WATER IS LIFE. As wildlife photographer Greg du Toit knows better than most.
winter wanderer
as summer becomes a memory in the south, the skies are a little quieter as the migrants have returned to the warming north. But one bird endemic to the southern African region takes its own little winter journey.
when perfect isn't enough
Egg signatures and forgeries in the cuckoo-drongo arms race
Southern SIGHTINGS
The late summer period naturally started quietening down after the midsummer excitement, but there were still some classy rarities on offer for birders all over the subregion. As always, none of the records included here have been adjudicated by any of the subregion's Rarities Committees.
flood impact on wetland birds
One of the features of a warming planet is increasingly erratic rainfall; years of drought followed by devastating floods. Fortunately, many waterbirds are pre-adapted to cope with such extremes, especially in southern Africa where they have evolved to exploit episodic rainfall events in semi-arid and arid regions. But how do waterbirds respond to floods in areas where rainfall - and access to water - is more predictable? Peter Ryan explores the consequences of recent floods on the birds of the Western Cape's Olifants River valley.
a star is born
It’s every producer’s dream to plan a wildlife television series and pick the right characters before filming.
