Investigations of urbanization effects on birds have focused mainly on breeding traits expressed after the nest-building stage (e.g. first-egg date, clutch size, breeding success, and offspring characteristics). Urban studies largely ignored how and why the aspects of nest building might be associated with the degree of urbanization. As urban environments are expected to present novel environmental changes relative to rural environments, it is important to evaluate how nest-building behavior is impacted by vegetation modifications associated with urbanization. To examine nest design in a Mediterranean city environment, we allowed urban great tits (Parus major) to breed in nest boxes in areas that differed in local vegetation cover. We found that different measures of nest size or mass were not associated with vegetation cover. In particular, nests located adjacent to streets with lower vegetation cover were not smaller or lighter than nests in parks with higher vegetation cover. Nests adjacent to streets contained more pine needles than nests in parks. In addition, in nests adjacent to streets, nests from boxes attached to pine trees contained more pine needles than nests from boxes attached to other trees. We suggest that urban-related alterations in vegetation cover do not directly impose physical limits on nest size in species that are opportunistic in the selection of nesting material. However, nest composition as reflected in the use of pine needles was clearly affected by habitat type and the planted tree species present, which implies that rapid habitat change impacts nest composition. We do not exclude that urbanization might impact other aspects of nest building behaviour not covered in our study (e.g. costs of searching for nest material), and that the strengths of the associations between urbanization and nest structures might differ among study populations or species.

中文翻译：

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不断变化的世界中的巢穴设计：以地中海城市环境为案例研究的大山雀 Parus 主要巢穴。

城市化对鸟类影响的研究主要集中在筑巢阶段后表现出的繁殖特征（例如第一个蛋日期、离合器大小、繁殖成功率和后代特征）。城市研究在很大程度上忽略了筑巢的各个方面如何以及为什么与城市化程度相关。由于预计城市环境将呈现相对于农村环境的新环境变化，因此评估筑巢行为如何受到与城市化相关的植被改变的影响非常重要。为了检查地中海城市环境中的巢穴设计，我们允许城市大山雀（Parus major) 在当地植被覆盖不同的地区的巢箱中繁殖。我们发现巢大小或质量的不同测量值与植被覆盖无关。特别是，位于植被覆盖度较低的街道附近的巢穴并不比植被覆盖度较高的公园中的巢穴更小或更轻。靠近街道的巢穴比公园里的巢穴含有更多的松针。此外，在靠近街道的巢穴中，附着在松树上的盒子里的松针比附着在其他树上的盒子里的松针多。我们认为，与城市相关的植被覆盖变化不会直接对选择筑巢材料的机会主义物种的巢大小施加物理限制。然而，使用松针所反映的巢构成明显受到栖息地类型和存在的种植树种的影响，这意味着栖息地的快速变化会影响巢的构成。我们不排除城市化可能会影响我们研究中未涵盖的筑巢行为的其他方面（例如寻找巢穴材料的成本），并且城市化与巢穴结构之间的关联强度可能因研究种群或物种而异。