Research press release


Nature Communications

Zoology: Sharing is key to wild dog hunting success

森林地帯に生息する絶滅危惧種のリカオン(Lycaon pictus)は、何度も短距離ダッシュして狩猟を行うが、個別の成功率は低い。ところが、リカオンは同じ群れの仲間が仕留めた獲物を分かち合うことでエネルギーの無駄を補っていることが明らかになった。この研究結果を報告する2編の論文が掲載される。


今回、Alan Wilsonたちは、ボツワナにおいて群れで生息する6頭のリカオン全てに高分解能データの得られるGPS首輪を取り付けて、5か月以上にわたって狩猟に出かけた個体の動きを追跡観察した。すると、従来の学説に反し、個体間の協力行動や長距離の狩猟を示す証拠はほとんど得られず、大部分の追跡行動は、短距離ダッシュであり、殺傷率は約15%と比較的低かった。つまり、100回の追跡で仕留めた獲物は15匹ということだった。


Endangered African wild dogs (Lycaon pictus) living in woodland habitats hunt using multiple short-distance bursts with low individual success rates, but share successful kills among pack members in order to offset lost energy, find two studies published in Nature Communications.

Pursuit predators expend a lot of energy chasing prey, although this high energetic demand may be offset if cooperative hunting by many individuals allows for larger prey to be killed and shared. African wild dogs are thought of as a prime example of efficient cooperative hunters, and have been recorded in open savannah pursuing large prey at relatively low speeds, over long distances within collaborative groups. However, populations of this endangered species are now restricted to more densely wooded savannah, where it has been unclear if this hunting strategy is successful.

Alan Wilson and colleagues attach high-resolution GPS collars to all members of a pack of six African wild dogs in Botswana, and track their movements during hunting trips over more than five months. They find that, contrary to previous assumptions, there was little evidence of cooperation between individuals or long-distance hunting episodes, with the majority of chases being characterised by short distance bursts, with a relatively low kill rate of around 15% (i.e. they kill 15 prey out of 100 they chase).

In a separate paper, the same authors use an energy-balance model to estimate the energetic costs (versus the returns) of this hunting strategy, and show that these costly pursuits are offset by packs sharing successful kills among the group. The authors compare this strategy to the sprint-pursuit behaviour of cheetahs which is energetically more demanding but has a higher kill rate (around 26%), and find that although an African wild dog hunting alone is about half as efficient as a cheetah in terms of the cost versus return of hunting, wild dogs hunting in packs are almost three times more efficient than cheetahs. These studies suggest that African wild dogs have a more robust energy strategy than previously thought, and that such a flexible hunting behaviour could be crucial for their continued survival in less favoured habitats.

doi: 10.1038/ncomms11033 | 英語の原文

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