Social discrimination and aggression by laying hens in large groups: from peck orders to social tolerance
Social discrimination and aggression by laying hens in large groups: from peck orders to social tolerance
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DOI：
10.1016/j.applanim.2003.08.010
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发表时间：
2003-12-02
影响因子：
2.3
通讯作者：
Keeling, LJ
中科院分区：
文献类型：
--
作者：
D'Eath, RB;Keeling, LJ
家鸡（Gallus gallus arcticus）自然地生活在小群体中，具有最有可能基于建立战斗的优势等级（啄食顺序），其次是涉及个体识别的地位记忆评估。在较大的群体中，这种系统被认为是崩溃的，母鸡可能会通过变得不那么具有攻击性或将它们的活动限制在限定的“领土”内来适应。在本研究中，我们测试了10只和120只的蛋鸡区分不熟悉的鸟类的能力。将受试者置于带垂直条的试验笼中，置于家庭围栏外的两个位置之一。在四个测试日的每一天，将来自每组大小的16只受试母鸡呈现给它们的家组（熟悉的）和相同大小的不同组（不熟悉的）。在一半的试验日，各组在围栏之间交换，以控制位置的影响。无论地点，母鸡在小团体之间的熟悉（F）和不熟悉（U）的科目，表现出更多的攻击对不熟悉的母鸡（企图打架：F = 18.8%，U = 56.3%的测试;所有的侵略：F = 60.9%，U = 85.9%的测试）。在大群体中，对受试者的攻击性总体水平降低，因为尝试打架是罕见的（F = 0.0%，U = 4.7%的测试），并且攻击性结果在对不熟悉或熟悉的母鸡的反应中没有差异（F = 46.9%，U = 42.2%的测试）。在这些大的群体中没有群伴/陌生人歧视，这使得这些母鸡不太可能根据群体内的个体识别来进行传统的啄食顺序。无论测试笼在围栏旁边的位置如何，大群中的某些个体母鸡更有可能接近它，没有证据表明母鸡在围栏内有有限的“领土”。在大的群体中（但不是在小的群体中），接近并具有攻击性的母鸡都比受试者更重，鸡冠也更大。两者合计，这些研究结果是一致的想法，在大组母鸡变得不那么积极，并可能改变他们的社会制度，其中的主导地位是通过直接评估和“状态信号”，而不是记住的个人评估的一个小组啄食顺序。(C)2003 Elsevier B. V.保留所有权利。
Domestic fowl (Gallus gallus domesticus) naturally live in small groups, with a dominance hierarchy (pecking order) which is most likely based on establishment fights, followed by remembered assessment of status involving individual recognition. In larger groups, this system is thought to break-down, and hens may adapt by becoming less aggressive, or by restricting their movements to defined 'territories'. In the present study, we tested the ability of laying hens living in groups of 10 and 120 to discriminate flockmates from unfamiliar birds. Subjects were presented in test cages with vertical bars, positioned outside the home pens in one of two places. Sixteen subject hens from each group size were presented to their home group (familiar) and a different group of the same size (unfamiliar) on each of four test days. For half of the test days, the groups were swapped between pens to control for the effect of location. Regardless of the location, hens in small groups discriminated between familiar (F) and unfamiliar (U) subjects by showing more aggression towards unfamiliar hens (attempted fights: F = 18.8%, U = 56.3% of tests; all aggression: F = 60.9%, U = 85.9% of tests). In large groups, the overall level of aggression towards subjects was reduced in that attempted fights were rare (F = 0.0%, U = 4.7% of tests), and aggressive outcomes were no different in response to unfamiliar or familiar hens (F = 46.9%, U = 42.2% of tests). The absence of flockmate/stranger discrimination in these large groups makes it unlikely that these hens had a conventional pecking order based on individual recognition within the group. Regardless of the location of the test cage beside the pen, certain individual hens in large groups were more likely to approach it, showing no evidence that hens have limited 'territories' within the pen. In large groups (but not in small), hens that approached and were aggressive were both heavier and had larger combs than the subjects. Taken together, these findings are consistent with the idea that in large groups hens become less aggressive and may change their social system to one where dominance is determined through direct assessment and 'status signalling' rather than the remembered individual assessment of a small group pecking order. (C) 2003 Elsevier B.V. All rights reserved.