Andreozzi Chelsea L, Merenlender Adina M
Department of Environmental Science, Policy, and Management, University of California, Berkeley, 130 Mulford Hall, Berkeley, CA 94720, United States.
J Mammal. 2024 Jul 2;105(5):988-1000. doi: 10.1093/jmammal/gyae070. eCollection 2024 Oct.
Bats are among the least well-known mammals, particularly in terms of their behavior and activity patterns during the winter. Here, we use passive acoustic monitoring to overcome some of the challenges inherent in surveying cryptic forest bats during the wet season to quantify overwintering behavior for 11 species in California coast redwood forests under varying microclimates. Because different species are active at different forest heights, we also examined the effect of acoustic detector placement (treetop or ground level). Generalized linear mixed models were used to relate acoustic detection probability for 8 species to daytime and nighttime temperature, relative humidity, water vapor pressure, and detector placement. The results indicate that daytime maximum temperature best explained variation in nightly probability of detection, and temperature threshold at which bats were predicted to be detected varied considerably across species. By using more precise species detection methods, we were able to resolve significant differences in activity patterns between and , 2 species with similar acoustic signatures that are often lumped together. was predicted to have a 50% probability of detection at maximum daytime temperature as low as 12.5 °C, whereas was not predicted to have 50% detection probability until maximum daytime temperature was at least 22 °C, suggesting that spends less time in torpor. Also, monitoring at the top of the canopy revealed 4 migratory species to be present in the ecosystem on significantly more monitoring nights than could be observed using conventional ground-based monitoring methods. Improving winter bat survey methods provides evidence that diverse bat species are more active in redwood forests during the winter than previously documented. This finding suggests that coastal forests could provide important winter bat habitat for both resident and migratory species.
蝙蝠是最鲜为人知的哺乳动物之一，尤其是在冬季它们的行为和活动模式方面。在此，我们使用被动声学监测来克服在雨季调查隐秘的森林蝙蝠时所固有的一些挑战，以量化加利福尼亚海岸红木森林中11个物种在不同小气候条件下的越冬行为。由于不同物种在森林的不同高度活动，我们还研究了声学探测器放置位置（树顶或地面）的影响。使用广义线性混合模型将8个物种的声学探测概率与白天和夜间温度、相对湿度、水汽压以及探测器放置位置相关联。结果表明，白天最高温度最能解释夜间探测概率的变化，并且预测蝙蝠被探测到的温度阈值在不同物种间差异很大。通过使用更精确的物种探测方法，我们能够分辨出两种声学特征相似且常被归为一类的物种——[物种1]和[物种2]在活动模式上的显著差异。预测[物种1]在白天最高温度低至12.5°C时就有50%的被探测概率，而[物种2]直到白天最高温度至少为22°C时才预计有50%的被探测概率，这表明[物种1]处于蛰伏状态的时间较少。此外，在树冠顶部进行监测发现，与传统的地面监测方法相比，在更多的监测夜晚发现生态系统中存在4种迁徙物种。改进冬季蝙蝠调查方法提供了证据，表明在冬季红木森林中，多种蝙蝠物种比以前记录的更为活跃。这一发现表明，沿海森林可能为留居和迁徙物种提供重要的冬季蝙蝠栖息地。
