Jackson Craig R, Maddox Thomas, Mbise Franco P, Stokke Bård G, Belant Jerrold L, Bevanger Kjetil, Durant Sarah M, Fyumagwa Robert, Ranke Peter S, Røskaft Eivin, May Roel, Fossøy Frode
Norwegian Institute for Nature Research Trondheim Norway.
Fauna and Flora International Cambridge UK.
Ecol Evol. 2020 May 19;10(13):6769-6774. doi: 10.1002/ece3.6366. eCollection 2020 Jul.
Carrion represents an unpredictable and widely distributed primary food source for vultures and other avian scavengers. Avian scavengers in African savanna ecosystems are reported to rely exclusively on visual stimuli to locate carcasses. However, carnivores' predation of large mammalian herbivores and subsequent competition for access to the carcass can result in considerable noise, often audible over long distances and for prolonged periods. Vultures and other avian scavengers may therefore detect and respond to these auditory cues, as do the mammalian carnivores alongside which vultures have coevolved, but this has not been investigated to date. Working in the Serengeti ecosystem, Tanzania, we used diurnal auditory broadcasts to simulate predation and competitive carnivore feeding interactions. Based on the current understanding of avian scavenger ecology, we hypothesized that avian responses to call-in stations would be evoked exclusively by visual, rather than auditory, cues. We therefore predicted that (a) the arrival of avian scavengers at call-in stations should be preceded and facilitated by mammalian carnivores and that (b) the arrival of avian scavengers would be positively correlated with the number of mammalian scavengers present, which would increase detectability. We recorded 482 birds during 122 separate playback events. In 22% of these instances, avian scavengers arrived first, ruling out responses based exclusively on visual observations of mammalian carnivores, thereby contradicting our first prediction. Furthermore, the first avian arrivals at survey sessions were inversely related to the number of hyenas and jackals present, contradicting our second prediction. Since no bait or carcasses were used during the experiments, these responses are indicative of the birds' ability to detect and respond to audio stimuli. Our findings challenge the current consensus of sensory perception and foraging in these species and provide evidence that avian scavengers have the ability to use sound to locate food resources.
腐肉是秃鹫和其他食腐鸟类不可预测且分布广泛的主要食物来源。据报道，非洲稀树草原生态系统中的食腐鸟类完全依靠视觉刺激来定位尸体。然而，食肉动物对大型食草哺乳动物的捕食以及随后对尸体的争夺会产生相当大的噪音，这种噪音通常能在远距离长时间听到。因此，秃鹫和其他食腐鸟类可能会像与它们共同进化的食肉哺乳动物一样，检测并对这些听觉线索做出反应，但迄今为止尚未对此进行研究。在坦桑尼亚的塞伦盖蒂生态系统中，我们利用日间听觉广播来模拟捕食和食肉动物的竞争性进食互动。基于目前对食腐鸟类生态学的理解，我们假设食腐鸟类对呼叫站的反应完全是由视觉而非听觉线索引发的。因此，我们预测：（a）食腐鸟类到达呼叫站之前应该有食肉哺乳动物在场并为其提供便利，且（b）食腐鸟类的到达与在场的食腐哺乳动物数量呈正相关，这会增加可探测性。在122次单独的播放事件中，我们记录到了482只鸟。在这些情况中，22%的情况下食腐鸟类最先到达，这排除了完全基于对食肉哺乳动物的视觉观察做出反应的可能性，从而与我们的第一个预测相矛盾。此外，在调查时段最先到达的食腐鸟类与在场的鬣狗和胡狼数量呈负相关，这与我们的第二个预测相矛盾。由于实验过程中未使用诱饵或尸体，这些反应表明鸟类有能力检测并对音频刺激做出反应。我们的研究结果挑战了目前关于这些物种感官感知和觅食的共识，并提供了证据表明食腐鸟类有能力利用声音来定位食物资源。
