To flee or not to flee...? Red-billed Queleas flock tightly to evade a Yellow-billed Kite. The 'fire-drill' hypothesis proposes that the frequent false-alarm flights by foraging flocks of birds help to prepare them for the real thing.
Many birds feed in flocks to reduce the risk of predation. By doing so, they benefit in three ways. First, because there are more eyes scanning for threats, the probability of detecting an approaching predator increases with group size. A linked benefit of this collective vigilance is that by having others to help spot predators, birds in flocks can spend more time feeding.
Secondly, by forming a cohesive group that twists and turns together in flight, flocking birds confuse predators, reducing their success. And thirdly, even if the predator succeeds in killing one member of the group, the risk of predation to any one individual decreases with group size. For group foraging to persist, these benefits have to outweigh the potential disadvantages, such as competition for food and the distraction of social interactions.
この記事は African Birdlife の May/June 2022 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 May/June 2022 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。
すでに購読者です? サインイン
EXPLORING NEW HORIZONS
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
The Walker Bay Diversity Trail is a leisurely hike with a multitude of flowers, feathers and flavours along the way.
Living forwards
How photographing birds helps me face adversity
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.
