Edible dormice (Glis glis) can remain entirely solitary but frequently share sleeping sites with conspecifics in groups of up to 16 adults and yearlings. Here, we analysed grouping behaviour of 4564 marked individuals, captured in a 13-year study in nest boxes in a deciduous forest. We aimed to clarify (i) whether social thermoregulation is the primary cause for group formation and (ii) which factors affect group size and composition. Dormice temporarily formed both mixed and single-sex groups in response to acute cold ambient temperatures, especially those individuals with small body mass. Thus, thermoregulatory huddling appears to be the driving force for group formation in this species. Huddling was avoided-except for conditions of severe cold load-in years of full mast seeding, which is associated with reproduction and high foraging activity. Almost all females remained solitary during reproduction and lactation. Hence, entire populations of dormice switched between predominantly solitary lives in reproductive years to social behaviour in non-reproductive years. Non-social behaviour pointed to costs of huddling in terms of competition for local food resources even when food is generally abundant. The impact of competition was mitigated by a sex ratio that was biased towards males, which avoids sharing of food resources with related females that have extremely high energy demands during lactation. Importantly, dormice preferentially huddled in male-biased groups with litter mates from previous years. The fraction of related individuals increased with group size. Hence, group composition partly offsets the costs of shared food resources via indirect fitness benefits.

中文翻译：

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社会体温调节的使用随着脉冲资源消耗者的肥大播种和繁殖而波动。


食用睡鼠 (Glis glis) 可以完全独居，但经常与同种动物共享睡眠地点，成群最多可容纳 16 只成年睡鼠和一岁幼鼠。在这里，我们分析了 4564 个标记个体的分组行为，这些个体是在落叶林巢箱中进行的一项为期 13 年的研究中捕获的。我们的目的是澄清（i）社会体温调节是否是群体形成的主要原因，以及（ii）哪些因素影响群体规模和组成。为了应对严寒的环境温度，睡鼠会暂时形成混合群体和单一性别群体，尤其是那些体重较小的个体。因此，体温调节的聚集似乎是该物种群体形成的驱动力。在满量播种的年份里，除了严寒负荷的条件外，避免了挤作一团，这与繁殖和高觅食活动有关。几乎所有雌性在繁殖和哺乳期间都保持独居。因此，整个睡鼠种群在繁殖期的主要独居生活转变为非繁殖期的社会行为。非社会行为表明，即使食物普遍充足，但为了争夺当地食物资源而挤在一起的成本也很高。偏向雄性的性别比例减轻了竞争的影响，这避免了与哺乳期能量需求极高的相关雌性共享食物资源。重要的是，睡鼠优先与前几年的同窝同伴挤在雄性偏向的群体中。相关个体的比例随着群体规模的增加而增加。因此，群体组成通过间接的健身效益部分抵消了共享食物资源的成本。