Glucocorticoids have wide-ranging effects on animals' behaviour, but many of these effects remain poorly understood because numerous confounding factors have often been neglected in previous studies. Here, we present data from a 2-year study of 7 groups of wild Verreaux's sifakas (Propithecus verreauxi), in which we examined concentrations of faecal glucocorticoid metabolites (fGCMs, n = 2350 samples) simultaneously in relation to ambient temperatures, food intake, rank, reproduction, adult sex ratios, social interactions, vigilance and self-scratching. Multi-variate analyses revealed that fGCM concentrations were positively correlated with increases in daily temperature fluctuations and tended to decrease with increasing fruit intake. fGCM concentrations increased when males were sexually mature and began to disperse, and dominant males had higher fGCM concentrations than subordinate males. In contrast to males, older females showed a non-significant trend to have lower fGCM levels, potentially reflecting differences in male and female life-history strategies. Reproducing females had the highest fGCM concentrations during late gestation and had higher fGCM levels than non-reproducing females, except during early lactation. Variation in fGCM concentrations was not associated with variation in social interactions, adult sex ratios, vigilance and self-scratching. Altogether, we show that measures of glucocorticoid output constitute appropriate tools for studying energetic burdens of ecological and reproductive challenges. However, they seem to be insufficient indicators for immediate endocrinological responses to social and nonsocial behaviours that are not directly linked to energy metabolism.

中文翻译：

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野生Verreaux sifakas中糖皮质激素代谢物浓度的动态和决定因素。

糖皮质激素对动物的行为具有广泛的影响，但由于许多混杂因素在以前的研究中经常被忽略，因此对这些作用中的许多作用仍知之甚少。在这里，我们提供了一项对7组野生Verreaux sifakas（Propithecus verreauxi）进行的为期2年研究的数据，其中我们同时检查了粪便糖皮质激素代谢物（fGCM，n = 2350个样品）的浓度与环境温度，食物摄入量，等级，生育，成年性别比例，社交互动，警惕和自我抓挠。多变量分析显示，fGCM浓度与每日温度波动的增加呈正相关，并且随着水果摄入量的增加而趋于下降。当男性性成熟并开始消散时，fGCM浓度会增加，优势男性的fGCM浓度高于下级男性。与男性相反，年龄较大的女性表现出较低的fGCM水平的趋势不明显，这可能反映了男性和女性生活史策略的差异。繁殖女性在妊娠后期具有最高的fGCM浓度，并且与非繁殖女性相比具有更高的fGCM水平（早期哺乳期除外）。fGCM浓度的变化与社交互动，成人性别比例，警惕性和自我抓挠的变化无关。总而言之，我们表明糖皮质激素输出的量度构成了研究生态和生殖挑战的能量负担的适当工具。然而，