Abstract The global climate is changing faster than previously anticipated. Although scientists expect cumulatively deleterious impacts to birds and other wildlife, effects on individual species are likely more complex. The California Department of Fish and Wildlife has monitored >100 songbirds across 37,600 km2 of Northern California conifer forests for close to two decades to facilitate informed, science-based conservation planning. The study area represents 42% of all conifer forests in the state. Autonomous sound recorders were used to survey birds at 1065 randomly distributed sites from 2002 to 2016. The richness of Neotropical migrants declined below 1515 m (90% CI: 1150–1950 m) elevation whereas it increased above this threshold after controlling for changes in tree cover due to forestry and wildfire. This finding suggests an overall upward shift in Neotropical migrant distributions in response to an annual 0.037 °C (90% CI: 0.029–0.045 °C) increase in mean daily May temperature during the timespan. Residents and altitudinal migrants may be less vulnerable to increasing temperatures, conversely, as evidence of elevational shifting was much weaker or non-existent for them. Yet for individual species, there were both declines and increases in occupancy. Rapid and mixed population trends, in combination with elevational range shifts, suggest that songbirds vary widely in their capacity to adapt to climate change and other stressors. Conservation of structurally-complex and fire resilient forests above ~1500 m elevation is paramount in helping to buffer songbirds against rising temperatures. The expansion of biodiversity monitoring across large taxonomic, spatial, and temporal extents is vital to effective conservation planning.

中文翻译：

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鸣禽对加利福尼亚针叶林气候变化的快速而多样的反应

摘要 全球气候变化的速度比先前预期的要快。尽管科学家预计会对鸟类和其他野生动物产生累积性有害影响，但对个别物种的影响可能更为复杂。加利福尼亚州鱼类和野生动物部近 20 年来一直在北加利福尼亚州 37,600 平方公里的针叶林中监测了 100 多只鸣禽，以促进知情的、以科学为基础的保护规划。研究区域占该州所有针叶林的 42%。从 2002 年到 2016 年，使用自主录音机对 1065 个随机分布地点的鸟类进行了调查。新热带候鸟的丰富度在海拔 1515 m（90% CI：1150-1950 m）以下下降，而在控制树木变化后增加到该阈值由于林业和野火而覆盖。这一发现表明，随着时间跨度内 5 月平均每日温度每年增加 0.037 °C（90% CI：0.029–0.045 °C），新热带移民分布总体上移。相反，居民和高海拔移民可能不太容易受到气温升高的影响，因为对他们来说，海拔变化的证据要弱得多或根本不存在。然而，对于个别物种，入住率既有下降也有增加。快速和混合的人口趋势，加上海拔范围的变化，表明鸣禽适应气候变化和其他压力的能力差异很大。保护海拔约 1500 米以上的结构复杂且具有防火能力的森林对于帮助鸣禽抵御不断升高的温度至关重要。