Data from: Hot temperatures during the dry season reduce survival of a resident tropical bird

Understanding how climate change will shape species distributions in the future requires a functional understanding of the demographic responses of animals to their environment. For birds, most of our knowledge of how climate influences population vital rates stems from research in temperate environments, even though most of the Earth’s avian diversity is concentrated in the tropics. We evaluated effects of Southern Oscillation Index (SOI) and local temperature and rainfall at multiple temporal scales on sex-specific survival of a resident tropical bird, the Rufous-and-White Wren Thryophilus rufalbus, studied over 15 years in the dry forests of northwestern Costa Rica. We found that annual apparent survival of males was 8% higher than females, more variable over time, and responded more strongly to environmental variation than female survival, which did not vary strongly with SOI or local weather. For males, mean and maximum local temperatures were better predictors of survival than either rainfall or SOI, with high temperatures during the dry season and early wet season negatively influencing survival. These results suggest that, even for species adapted to hot environments, further temperature increases may threaten the persistence of local populations in the absence of distributional shifts.

要理解气候变化未来将如何重塑物种的分布格局，必先透彻掌握动物种群对其生存环境的种群统计学响应机制。就鸟类而言，当前学界关于气候如何影响种群生命参数的认知大多源自温带环境下的研究，而全球绝大多数鸟类多样性却集中于热带地区。我们针对定居性热带鸟类棕白鹪鹩（Thryophilus rufalbus），在哥斯达黎加西北部的干旱森林开展了长达15年的野外监测，评估了多时间尺度下的南方涛动指数（Southern Oscillation Index, SOI）、局地气温与降雨量对其性别特异性存活率的影响。研究结果显示：雄性个体的年度表观存活率较雌性高出8%，且随时间波动更为显著，对环境变化的响应强度也高于雌性；而雌性存活率并未随南方涛动指数或局地气象条件出现明显波动。对于雄性个体而言，局地平均气温与最高气温是比降雨量或南方涛动指数更有效的存活率预测因子，旱季与湿季早期的高温会对其存活率产生负面影响。上述结果表明，即便对于适应了高温环境的物种而言，若无法实现分布范围的转移，未来气温的进一步升高仍可能威胁其局地种群的存续。