Data from: Elevational changes in the avian community of a Mesoamerican cloud forest park

Harboring many range-restricted and specialized species, high elevation tropical cloud forests are diverse habitats represented in many protected areas. Despite this, many such areas receive little practical protection from deforestation and land conversion. Moreover, montane species may be more sensitive to climate change owing to various factors affecting community assembly across elevational gradients. Few studies have used annual monitoring to assess how biological communities in cloud forests may be shifting in response to habitat or climate change or assessed the efficacy of protected areas in buffering these effects. We analysed avifaunal community trends in a ten-year dataset of constant-effort bird point-count data in a cloud forest national park in Honduras, Central America. We found that species richness and diversity increased at higher elevations, but decreased at lower elevations. Abundances of most dietary and forest-dependency groups exhibited similar trends, and many key cloud forest species shifted upslope and/or increased in abundance. Taken together, our results suggest that the avian community is moving upslope and species composition is changing. Results for species richness and diversity were similar when only non-degraded transects were considered, suggesting the role of climate change as an important driver. At lower elevations, however, many species may be negatively affected by increased habitat degradation, favoring species with low forest-dependency. Continued habitat conversion and climate change could push the cloud forest bird community further upslope, potentially resulting in increased competition, mortality and even extirpation of some species. Increased protection is unlikely to mitigate the effects of climate change.

热带高海拔云雾林（cloud forest）孕育着众多分布范围受限的特化物种，是诸多保护区内极具代表性的多样生境。尽管如此，多数此类保护区仍难以获得针对森林砍伐与土地转换的切实保护。此外，由于诸多影响海拔梯度上群落组装的因素，山地物种对气候变化或许更为敏感。鲜有研究借助年度监测手段，评估云雾林内的生物群落如何随生境变化或气候变化发生演替，也鲜有研究评估保护区在缓冲此类影响方面的效能。我们针对中美洲洪都拉斯某云雾林国家公园内收集的、为期十年的恒定努力鸟类点计数（constant-effort bird point-count）数据集，分析了鸟类群落的动态趋势。研究发现，物种丰富度与多样性在高海拔区域呈上升趋势，而在低海拔区域则有所下降。多数食性类群与森林依存类群的种群丰度呈现相似趋势，且诸多关键云雾林物种向高海拔迁移或种群丰度上升。综合来看，研究结果表明鸟类群落正向高海拔迁移，物种组成亦发生改变。仅考虑未退化样线时，物种丰富度与多样性的分析结果保持一致，这表明气候变化是重要的驱动因素。但在低海拔区域，诸多物种或因生境退化加剧而受到负面影响，使得低森林依存度的物种更具生存优势。持续的生境转换与气候变化或将进一步推动云雾林鸟类群落向高海拔迁移，进而可能加剧种间竞争、提升种群死亡率，甚至导致部分物种局部灭绝。加强保护区保护或难以缓解气候变化带来的影响。