Increasing urbanisation and human pressure on lands have huge impacts on biodiversity. Some species, known as “urban exploiters”, manage to expand in urban landscapes, relying on human resources. The House Sparrow (Passer domesticus) is the perfect example of a human-commensal species. Surprisingly, this urban exploiter has been declining all over Europe over the past decades. The proximate causes of this decline remain poorly understood. We particularly lack understanding about urban habitat characteristics that are particularly unfavourable for House Sparrows. In the present study, we analysed fine-scale habitat characteristics of House Sparrow population sizes and trends using a fifteen-year House Sparrow census (2003–2017) covering the urban diversity of Paris (nearly 200 census sites), one of the densest European cities. We documented for the first time the dramatic decline (−89%) of the species in Paris over the study period. The temporal decline over the whole city correlates with the concomitant increase in the number of breeding Sparrowhawks. We could not detect statistical influences of annual variations in weather conditions and pollution. The decline of House Sparrows is spatially heterogeneous. Indeed, site-scale analyses revealed sharpest declines at sites that initially hosted the largest numbers of sparrows, which are areas with a relatively high proportion of green spaces and new buildings. Further experimental studies are now needed to disentangle the exact impact of specific characteristics of the urban environment on House Sparrow populations.

日益城市化和人类对土地的压力对生物多样性产生了巨大影响。一些被称为“城市剥削者”的物种依靠人力资源设法在城市景观中扩展。麻雀（Passer domesticus）是人类常见物种的完美典范。令人惊讶的是，过去几十年来，这个城市开发者在整个欧洲一直在下降。造成这种下降的主要原因尚不清楚。我们特别缺乏对麻雀特别不利的城市栖息地特征的了解。在本研究中，我们使用涵盖巴黎城市多样性（近200个人口普查点）的15年间麻雀人口普查（2003-2017年）分析了麻雀种群规模和趋势的精细尺度生境特征城市。在研究期间，我们首次记录了巴黎物种的急剧下降（-89％）。整个城市的时间下降与繁殖鹰雀数量的增加有关。我们无法检测到天气状况和污染年度变化的统计影响。麻雀的衰落在空间上是异质的。确实，站点规模的分析显示，最初容纳最多麻雀的站点下降幅度最大，而这些区域的绿地和新建筑物的比例相对较高。现在需要进一步的实验研究来弄清城市环境特定特征对麻雀种群的确切影响。