Shearer David J, Beilke Elizabeth A
Department of Biology, Ball State University, 2000 W University Ave, Muncie, IN, 47306, USA.
Department of Biology, Indiana State University, 600 North Chestnut Street, Terre Haute, IN, 47809, USA.
Anim Cogn. 2023 Mar;26(2):357-367. doi: 10.1007/s10071-022-01663-z. Epub 2022 Aug 5.
The ability to detect an incoming attack provides a final opportunity for an animal to avoid predation. In birds, vision is the main sensory mode in detecting attacks, but auditory cues likely play an important role. The role of auditory cues from predators themselves remains largely unstudied. We evaluated the ability of free-living, gregarious sparrows (Passerellidae) to recognize attacks based on the non-vocal sounds made by predators or indirect auditory cues of ongoing attacks, mainly in the form of brief wingbeat sequences from predatory and non-predatory birds. Behavioral responses to playbacks were video-recorded and expressed in terms of a flock's propensity to respond, either by flushing to cover, becoming vigilant, or both. Sparrows responded equally to hawk wingbeats and those of small passerines. Both predator and non-predator wingbeat sequences induced anti-predator responses, especially when played loudly. Loud control sounds, such as hammering, induced few responses. Birds also responded to the sounds of a walking and running terrestrial predator (a dog), but reactions to the walking predator often involved birds jumping onto objects for a better view of their surroundings rather than immediate flight to cover. In an additional experiment, we examined how characteristics of wingbeat sequences (i.e., the number and cadence of hawk wingbeats) affected passerine responses. It indicated that only two consecutive hawk wingbeats, presented at a natural cadence, are necessary to elicit a strong response to a playback. Single hawk wingbeats induced only weak escape responses, as did artificially slowed cadences. Birds in general likely possess the ability to recognize non-vocal, auditory cues of incoming attacks, which may be produced by approaching threats or departing congeners.
察觉来袭攻击的能力为动物提供了最后一次躲避捕食的机会。在鸟类中，视觉是察觉攻击的主要感官模式，但听觉线索可能也起着重要作用。来自捕食者自身的听觉线索的作用在很大程度上仍未得到研究。我们评估了自由生活的群居麻雀（雀科）基于捕食者发出的非声音信号或正在进行的攻击的间接听觉线索（主要是以捕食性和非捕食性鸟类短暂的振翅序列形式）识别攻击的能力。对回放的行为反应进行了视频记录，并以鸟群做出反应的倾向来表示，反应方式要么是飞离以躲避，变得警觉，或者两者皆有。麻雀对鹰的振翅声和小型雀形目鸟类的振翅声反应相同。捕食者和非捕食者的振翅序列都会引发反捕食反应，尤其是当大声播放时。响亮的对照声音，如锤击声，引发的反应很少。鸟类也会对行走和奔跑的陆生捕食者（一只狗）的声音做出反应，但对行走的捕食者的反应通常是鸟类跳到物体上以便更好地观察周围环境，而不是立即飞离躲避。在另一个实验中，我们研究了振翅序列的特征（即鹰振翅的次数和节奏）如何影响雀形目鸟类的反应。结果表明，以自然节奏呈现的仅两个连续的鹰振翅声就足以引发对回放的强烈反应。单个鹰振翅声仅引发微弱的逃避反应，人工放慢节奏时也是如此。一般来说，鸟类可能具备识别来袭攻击的非声音听觉线索的能力，这些线索可能由接近的威胁或离去的同类产生。
