Ornithological Station, Faculty of Biological Sciences, University of Wrocław, Wrocław 50-335, Poland.
Department of Ecology, Swedish University of Agricultural Sciences, Uppsala SE-750 07, Sweden.
Proc Natl Acad Sci U S A. 2023 May 9;120(19):e2208389120. doi: 10.1073/pnas.2208389120. Epub 2023 May 1.
Climate change affects timing of reproduction in many bird species, but few studies have investigated its influence on annual reproductive output. Here, we assess changes in the annual production of young by female breeders in 201 populations of 104 bird species (N = 745,962 clutches) covering all continents between 1970 and 2019. Overall, average offspring production has declined in recent decades, but considerable differences were found among species and populations. A total of 56.7% of populations showed a declining trend in offspring production (significant in 17.4%), whereas 43.3% exhibited an increase (significant in 10.4%). The results show that climatic changes affect offspring production through compounded effects on ecological and life history traits of species. Migratory and larger-bodied species experienced reduced offspring production with increasing temperatures during the chick-rearing period, whereas smaller-bodied, sedentary species tended to produce more offspring. Likewise, multi-brooded species showed increased breeding success with increasing temperatures, whereas rising temperatures were unrelated to reproductive success in single-brooded species. Our study suggests that rapid declines in size of bird populations reported by many studies from different parts of the world are driven only to a small degree by changes in the production of young.
气候变化影响了许多鸟类物种的繁殖时间，但很少有研究调查其对年度繁殖产量的影响。在这里，我们评估了 1970 年至 2019 年间，分布在各大洲的 104 种鸟类的 201 个繁殖种群中（N=745962 个巢）中，雌性繁殖者每年繁殖后代的数量的变化。总体而言，近几十年来，平均后代繁殖数量呈下降趋势，但在物种和种群之间存在相当大的差异。共有 56.7%的种群（17.4%显著）表现出后代繁殖量下降的趋势，而 43.3%的种群（10.4%显著）表现出增加的趋势。研究结果表明，气候变化通过对物种的生态和生活史特征产生复合影响，从而影响后代的繁殖数量。在育雏期，随着温度升高，候鸟和体型较大的物种后代繁殖数量减少，而体型较小、定居的物种往往会繁殖更多的后代。同样，多窝繁殖的物种随着温度升高繁殖成功率增加，而单窝繁殖的物种的繁殖成功率与温度升高无关。我们的研究表明，许多来自世界各地的不同研究报告的鸟类种群数量迅速减少，这在很大程度上是由幼鸟繁殖数量的变化所驱动的。
