Biology I, University of Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany.
Anim Cogn. 2011 Mar;14(2):245-57. doi: 10.1007/s10071-010-0358-1. Epub 2010 Dec 4.
Living in complex social systems requires perceptual and cognitive capacities for the recognition of group membership and individual competitors. Olfaction is one means by which this can be achieved. Many animals can identify individual proteins in urine, skin secretions, or saliva by scent. Additionally, marking behaviour in several mammals and especially in horses indicates the importance of sniffing conspecifics' faeces for olfactory recognition. To test this hypothesis, we conducted two separate experiments: Experiment 1 addressed the question of whether horses can recognise the group membership of other horses by sniffing their faeces. The horses were presented with four faecal samples: (1) their own, (2) those of other members of their own group, (3) those of unfamiliar mares, and (4) those of unfamiliar geldings. Experiment two was designed to assess whether horses can identify the group member from whom a faecal sample came. Here, we presented two groups of horses with faecal samples from their group mates in random distribution. As controls, soil heaps and sheep faecal samples were used. In experiment one, horses distinguished their own from their conspecifics' faeces, but did not differentiate between familiarity and sex. In experiment two, the horses from both groups paid most attention to the faeces of the horses from which they received the highest amount of aggressive behaviours. We therefore suggest that horses of both sexes can distinguish individual competitors among their group mates by the smell of their faeces.
生活在复杂的社会系统中，需要具备识别群体成员和个体竞争者的感知和认知能力。嗅觉就是实现这一目标的一种手段。许多动物可以通过气味识别尿液、皮肤分泌物或唾液中的个体蛋白质。此外，几种哺乳动物，尤其是马的标记行为表明，嗅探同种动物的粪便对于嗅觉识别非常重要。为了验证这一假设，我们进行了两项独立的实验：实验 1 探讨了马是否可以通过嗅闻粪便来识别其他马的群体归属。实验中向马呈现了四种粪便样本：（1）自己的粪便，（2）自己群体中其他成员的粪便，（3）陌生母马的粪便，（4）陌生公马的粪便。实验 2 旨在评估马是否可以从粪便样本中识别出群体成员。在这里，我们将两组马的粪便样本随机分配给它们的群体成员。作为对照，我们还使用了土堆和绵羊的粪便样本。在实验 1 中，马可以区分自己的粪便和同类的粪便，但无法区分熟悉度和性别。在实验 2 中，两组马都更关注那些来自它们收到最多攻击行为的马的粪便。因此，我们认为，无论是公马还是母马，都可以通过粪便的气味来区分群体中的个体竞争者。
