Given current urbanization trends, understanding the factors that affect local biodiversity is paramount for designing sound management practices. Existing evidence suggests that the assembly of urban communities is influenced by the environmental filtering of organisms based on their traits. Here, we investigate how environmental characteristics including isolation measurements affect the functional composition of avian assemblages in green spaces of Merida, Mexico, a Neotropical city. We sampled 22 sites, analyzed point-count data collected during fall migration, and characterized the habitat with regard to floristic and structural vegetation attributes, vegetation cover within green spaces, urban infrastructure, and isolation. We assessed the relationship between habitat descriptors and bird functional traits using RLQ and fourth-corner tests and compared trait–environment associations between resident and wintering species. Our results showed that functional composition of resident bird assemblages was linked to the environmental characteristics of the site, while the functional composition of wintering species was not. In particular, the degree of isolation revealed to be an important determinant of trait composition. Plant species richness, particularly native tree and shrub species, were critical for the functional composition of resident birds in green spaces. Our findings suggested shifts in body mass from less to more isolated green spaces. Specifically, we observed that large-bodied species predominated in isolated green spaces. This information is useful given the predicted increases in habitat isolation and transformation of green spaces due to urbanization.

中文翻译：

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新热带城市绿地鸟类群落功能构成的驱动因素：墨西哥梅里达的案例研究

鉴于当前的城市化趋势，了解影响当地生物多样性的因素对于设计合理的管理实践至关重要。现有证据表明，城市社区的组装受到基于生物特征的环境过滤的影响。在这里，我们调查了包括隔离测量在内的环境特征如何影响新热带城市墨西哥梅里达绿色空间中鸟类组合的功能组成。我们对 22 个地点进行了采样，分析了秋季迁徙期间收集的点数数据，并根据植物区系和结构植被属性、绿地内的植被覆盖、城市基础设施和隔离对栖息地进行了表征。我们使用 RLQ 和第四角测试评估了栖息地描述符与鸟类功能特征之间的关系，并比较了常驻物种和越冬物种之间的特征-环境关联。我们的研究结果表明，留鸟群的功能组成与场地的环境特征有关，而越冬物种的功能组成则没有。特别是，隔离程度是性状组成的一个重要决定因素。植物物种丰富度，尤其是本地乔木和灌木物种，对于绿地中留鸟的功能组成至关重要。我们的研究结果表明，体重从较少的绿色空间变为更加孤立的绿色空间。具体来说，我们观察到大型物种在孤立的绿色空间中占主导地位。