Ostreiher Roni, Heifetz Aviad
Department of Life Science , The Open University of Israel , The Dorothy de Rothschild Campus, 1 University Road, POB 808, Raanana 4353107 , Israel.
The Open University of Israel , The Dorothy de Rothschild Campus, 1 University Road, POB 808, Raanana 4353107 , Israel.
R Soc Open Sci. 2017 Feb 8;4(2):160738. doi: 10.1098/rsos.160738. eCollection 2017 Feb.
The sentinel behaviour of 38 Arabian babbler adult floaters, who lived alone within a territory belonging to a foreign group, was studied and compared with their own sentinel behaviour in the past, when they were group members. All floaters acted as sentinels and uttered 'alarm calls'. This suggests that sentinel activity is due at least, in part, to selfish motives. Floaters sentinelled less than they did as group members, with the decrease in sentinel activity sharper for ex-dominants than for ex-subordinates. One possible explanation for these differences is that sentinel activity is aimed not only at detecting predators, but also at detecting foreign conspecifics. Within a group, the latter incentive is stronger for breeding dominants than for subordinates, whereas all floaters alike may be trying to detect the owners of the territory in which they were roaming but also to avoid being detected by them. Other possible explanations are that floaters have less time and energy for sentinel activity because they are weaker or because foraging is more difficult in a foreign territory. This may be especially so for dominants who used to enjoy privileged access to food in their group. No significant difference was found in the rate of sentinels' 'alarm calls' between floaters and group members, suggesting that their main purpose is predator-prey communication, of which warning groupmates may be a side benefit.
对38只阿拉伯鸫鹛成年游荡者的哨兵行为进行了研究，这些游荡者独自生活在属于其他群体的领地内，并与它们过去作为群体成员时的哨兵行为进行了比较。所有游荡者都充当哨兵并发出“警报叫声”。这表明哨兵活动至少部分是出于自私动机。游荡者担任哨兵的次数比它们作为群体成员时少，前优势个体的哨兵活动减少幅度比前从属个体更大。这些差异的一个可能解释是，哨兵活动不仅旨在发现捕食者，还旨在发现外来同种个体。在一个群体中，后一种动机对繁殖优势个体比对从属个体更强，而所有游荡者可能都试图发现它们正在游荡的领地的主人，但同时也要避免被主人发现。其他可能的解释是，游荡者用于哨兵活动的时间和精力较少，因为它们较弱，或者因为在陌生领地觅食更困难。对于那些过去在群体中享有获取食物特权的优势个体来说，情况可能尤其如此。游荡者和群体成员之间在哨兵“警报叫声”的频率上没有发现显著差异，这表明它们的主要目的是捕食者与猎物之间的交流，而警告同伴可能是附带的好处。
