The population dynamics of urban animals has been so far remarkably understudied. At the same time, urban species’ population trends can provide important information on the consequences of environmental changes in cities. We modelled long-term population trends of 93 bird species breeding in urban areas in 16 European countries as a function of species’ traits, characterising variability in their urbanization and ecology. We found that: (i) earlier colonisers have more negative population trends than recent colonisers; (ii) more urbanized open habitat species had more positive population trends than less urbanized open habitat species; (iii) highly urbanized birds breeding above the ground had more negative trends than highly urbanized ground breeders. These patterns can be explained by several processes occurring in cities as well as outside city borders. Namely, (i) pre-industrial colonisers might struggle to persist in rapidly changing urban areas, limiting their foraging and breeding opportunities of the birds. (ii) Open habitats are under pressure of intensive agricultural exploitation in rural areas, which may negatively affect populations of less urbanized birds. In contrast, urban areas do not experience such pressure keeping the trends of urbanized open habitat species more positive. (iii) Differences in population trends between highly urbanized ground and above-ground breeders suggest that the latter may lose their breeding opportunities in modern buildings that do not provide suitable breeding sites. Our results indicate that even once successful, city dwellers may not keep pace with changes in urban areas, but these areas may also provide suitable habitats for biodiversity.

中文翻译：

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生态特征预测欧洲城市鸟类的种群趋势

迄今为止，人们对城市动物种群动态的研究还远远不够。同时，城市物种的种群趋势可以提供有关城市环境变化后果的重要信息。我们根据物种性状对 16 个欧洲国家城市地区繁殖的 93 种鸟类的长期种群趋势进行了建模，表征了其城市化和生态的变异性。我们发现：（i）早期殖民者比近期殖民者有更多的负面人口趋势； (ii) 城市化程度较高的开放栖息地物种比较城市化程度较低的开放栖息地物种具有更积极的种群趋势； (iii) 高度城市化的地面鸟类繁殖比高度城市化的地面繁殖有更多的负面趋势。这些模式可以通过发生在城市以及城市边界之外的几个过程来解释。也就是说，（i）前工业化的殖民者可能难以在快速变化的城市地区坚持下去，从而限制了鸟类的觅食和繁殖机会。 (ii) 开放栖息地面临农村地区集约化农业开发的压力，这可能对城市化程度较低的鸟类种群产生负面影响。相比之下，城市地区并没有经历这样的压力，使城市化开放栖息地物种的趋势更加积极。 (iii) 高度城市化的地面和地上繁殖者之间的种群趋势差异表明，后者可能会失去在不提供合适繁殖场所的现代建筑中繁殖的机会。我们的结果表明，即使一旦成功，城市居民可能无法跟上城市地区的变化，但这些地区也可能为生物多样性提供合适的栖息地。