Factors influencing overnight loss of body mass in the communal roosts of a social bird
Factors influencing overnight loss of body mass in the communal roosts of a social bird
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DOI：
10.1111/j.1365-2435.2008.01511.x
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发表时间：
2009-04-01
影响因子：
5.2
通讯作者：
McGowan, Andrew
中科院分区：
文献类型：
--
作者：
Hatchwell, Ben J.;Sharp, Stuart P.;McGowan, Andrew
1. 假设鸟类的集体栖息行为可以通过降低夜间生存所需的能量消耗来降低饥饿的风险。然而，所获得的代谢益处可能取决于多种因素，包括个体在栖息地内的位置。2．长尾山雀 Aegithalos caudatus L. 是一种社会性物种，在非繁殖季节成群生活，形成线性栖息群，个体竞争以避免占据栖息地两端的边缘位置。通过对 18 个暂时圈养的长尾山雀群的观察，我们研究了位置和其他因素对栖息期间损失质量的影响。3．我们发现，平均而言，长尾山雀在一夜之间损失了约 9% 的体重，而占据栖息地外围位置的个体比占据内部位置的个体损失的质量明显更多。4。隔夜质量损失与最低温度有关，在 4 摄氏度时最大，随着温度的升高和降低而减少。这一结果表明，长尾山雀可能利用兼性夜间低温来减少低环境温度下的能量消耗。质量损失也往往随着群体规模的增加而增加，这可能是因为较大群体中对内部位置的竞争更加激烈，尽管我们没有直接证据证明这一点。质量损失也与栖息时的质量呈正相关，雄性损失的质量略多于雌性。5．没有证据表明，个体在栖息时根据其可能的栖息位置战略性地调整其日常质量，即使外部位置始终如一且因此可以预见地由同一个人在连续的夜晚占据。6。我们得出的结论是，长尾山雀通过集体栖息来减轻夜间生存的成本，但获得的好处因栖息地内的位置而异，这解释了之前对栖息地形成过程中竞争性相互作用的观察。7。从公共行为中获得的好处可能因个人而异，并且这些好处的冲突程度可能取决于内在和外在因素。
1. Communal roosting behaviour in birds is hypothesized to reduce the risk of starvation by lowering the energetic expenditure required to survive the night. However, the metabolic benefit gained is likely to depend on various factors, including an individual's position within the roost.2. The long-tailed tit Aegithalos caudatus L. is a social species that lives in flocks during the non-breeding season, forming linear roosting huddles in which individuals compete to avoid occupying the peripheral positions at either end of the roost. Using observations of 18 temporarily captive flocks of long-tailed tits, we examine the effects of position and other factors on the mass lost during roosting.3. We found that, on average, long-tailed tits lost about 9% of their body mass overnight, and that individuals occupying the peripheral positions in a roost lost significantly more mass than those occupying inner positions.4. Overnight mass loss was related to minimum temperature, being greatest at 4 degrees C and decreasing at higher and lower temperatures. This result suggests that long-tailed tits may use facultative nocturnal hypothermia to reduce energetic costs at low ambient temperature. Mass loss also tended to increase with group size, perhaps because of the greater competition for inner positions in larger flocks, although we have no direct evidence for this. Mass loss was also positively correlated with mass when going to roost, and males lost marginally more mass than females.5. There was no evidence that individuals strategically adjusted their daily mass when going to roost in relation to their likely roosting position even though outer positions are consistently and therefore predictably occupied by the same individuals on successive nights.6. We conclude that long-tailed tits mitigate the costs of surviving the night by roosting communally, but the benefits gained vary in relation to position within the roost, explaining previous observations of competitive interactions during roost formation.7. The benefit derived from communal behaviour is likely to vary among individuals and the degree of conflict over these benefits is likely to depend on both intrinsic and extrinsic factors.