Erhardt Stefanie, Förschler Marc I, Fietz Joanna
Department of Zoology, Institute of Biology University of Hohenheim Stuttgart Germany.
KomBioTa - Center of Biodiversity and Integrative Taxonomy University of Hohenheim Stuttgart Germany.
Ecol Evol. 2025 Apr 21;15(4):e71340. doi: 10.1002/ece3.71340. eCollection 2025 Apr.
Biodiversity is decreasing worldwide, and early indicators are needed to identify endangered populations before they start to decline in abundance. In mammals, body mass (BM) is regarded as an indicator of fitness, and its loss is used as an early warning signal preceding population decline. The garden dormouse (, Gliridae, BM: 60-110 g) is a small mammalian hibernator that has disappeared from over 50% of its former range in the last decades. The aim of this study was to investigate whether garden dormice from a presumably thriving and stable population already show early warning signals, which may precede a population decline. We therefore conducted capture-mark-recapture studies during 2003-2005 (Period 1) and 2018-2021 (Period 2) in the Northern Black Forest, one of its last natural distribution areas in Germany. We collected fecal samples, measured BM, and tibia length as a proxy for size and age. Results revealed that in Period 2 adult dormice had a significantly lower (12%) pre-hibernation BM, corrected for body size, and juveniles showed a significantly lower BM gain after weaning than nearly two decades ago. Fecal samples collected in Period 2 showed that arthropods represented the main food residues in fecal samples during juvenile growth and pre-hibernation fattening. Ambient temperature during hibernation showed no correlation with BM at emergence. We could not detect a phenological time shift in reproduction; however, we found only one birth peak in Period 2, compared with two birth peaks in Period 1. Observed changes in BM and reproduction pattern represent early warning signals, as they point to an insufficient availability of high-quality food, which prevents dormice from meeting their nutritional requirements, with potentially serious consequences for their reproductive success and survival. As arthropods are the dominant food resource, their decline may at least partly explain this phenomenon.
全球生物多样性正在减少，因此需要早期指标来在濒危种群数量开始下降之前识别它们。在哺乳动物中，体重被视为健康状况的一个指标，体重下降被用作种群数量下降之前的一个早期预警信号。花园睡鼠（睡鼠科，体重：60 - 110克）是一种小型哺乳动物冬眠者，在过去几十年里，它已从其原分布范围的50%以上区域消失。本研究的目的是调查来自一个可能繁荣且稳定的种群的花园睡鼠是否已经显示出可能先于种群数量下降的早期预警信号。因此，我们在2003 - 2005年（第1阶段）和2018 - 2021年（第2阶段）于德国最后一个自然分布区域之一的北黑森林进行了标记重捕研究。我们收集了粪便样本，测量了体重以及作为体型和年龄指标的胫骨长度。结果显示，在第2阶段，成年睡鼠在经过体型校正后的冬眠前体重显著降低了12%，并且幼崽断奶后的体重增加也比近二十年前显著更低。在第2阶段收集的粪便样本表明，节肢动物是幼崽生长和冬眠前育肥期间粪便样本中的主要食物残渣。冬眠期间的环境温度与出蛰时的体重没有相关性。我们没有检测到繁殖物候时间的变化；然而，我们发现在第2阶段只有一个出生高峰，而在第1阶段有两个出生高峰。观察到的体重和繁殖模式的变化代表了早期预警信号，因为它们表明高质量食物的可获得性不足，这使睡鼠无法满足其营养需求，可能对它们的繁殖成功率和生存产生严重后果。由于节肢动物是主要的食物资源，它们的减少可能至少部分解释了这一现象。
