家燕营巢特征及其对城市环境的适应性

城市面积在全球范围内迅速扩张，一些鸟类种群通过改变营巢特征，在与自然生境截然不同的城市中筑巢繁殖。但目前城市环境对于鸟类营巢影响的研究较缺乏。为了解鸟类营巢对城市环境的适应，于2016、2019年在黑龙江哈尔滨的城市与乡村环境，分别测量家燕（Hirundo rustica）巢（如，大小及形状）及巢址特征等（如，距地面和屋顶距离）参数，以探究：（1）家燕巢特征在乡村及城市生境是否存在差异？（2）家燕巢特征在年际间是否存在变化？并为城市家燕种群的保护提供理论依据及合理建议。研究采用Kruskal-Wallis秩和检验以及Wilcoxon秩和检验比较分析所测量的巢特征参数在城乡之间、年际间的差异，并对组间参数进行线性判别分析（LDA，Linear Discriminant Analysis）。结果发现，城乡间具有显著差异：（1）与乡村相比，城市巢距离屋顶更远，距地相对更近（P<0.05）；（2）城市巢更浅（P<0.05）；（3）从2016到2019年，城市和乡村巢都变得更深，半径更大（P<0.05）。根据这些发现，推测城市楼房建筑的楼道为家燕繁殖提供了相对更为封闭、安全的环境，旧巢及较为丰富的支撑物为家燕提供了适宜的巢址，有可能节省亲鸟在营巢上的繁殖投入；但同时应当警惕门窗关闭、资源受限、人为干扰等不利因素可能造成的生态陷阱。

Nesting characteristics and plasticity of barn swallow (Hirundo rustica) in urban environment

Since the 20th century, urban areas have rapidly expanded worldwide, and some bird populations have changed their nesting characteristics in urban habitat that completely differed from their natural habitats. However, we still have limited knowledge about the impact of urban environment on bird nesting. Both the positive and negative urbanization effects on birds nesting and breeding outputs have been reported. In order to understand the plasticity of bird nests in urban environment, this study measured 10 nesting (e.g., size and shape) and site parameters (e.g., distance from the ground and roof) of barn swallow (Hirundo rustica) from both urban and rural habitats in Harbin, Heilongjiang Province in 2016 and 2019. We aimed to explore:(1) Did any difference exist in nest characteristics between rural and urban habitats? (2) Did the nest characteristics of barn swallow vary between years? We also provided the theoretical basis and reasonable suggestions for protection of urban barn swallow populations. Kruskal-wallis rank sum test and Wilcoxon rank sum test were used to compare and analyze the differences between urban and rural nests and inter-annual characteristic parameters, and Linear Discriminant Analysis (LDA) was performed on characteristics of urban and rural nests in 2016 and 2019. The results showed the difference between urban and rural areas:(1) compared with nests in rural habitat, urban nests were farther from the roof and closer to the ground relatively (P<0.05), and to avoid bad weather or predation may caused rural nests much higher from grounds and closer to roofs which built outside doors; (2) The nests in urban were much shallower than those in rural habitat (P<0.05), and may correlate with saving earths or times invested in building nests which above supporting substrates. As for difference from 2016 to 2019, (3) both urban and rural nests became deeper with larger radius (P<0.05) which assumed that because the barn swallows reused the old nests with repairs, which made the nests became bigger and deeper with the using time increased many. In terms of these results, we assumed that the stairway corridors in urban buildings provided a relatively closed and safe environment for barn swallows, and the old nests and abundant anthropogenic upholders provided suitable nesting sites for them, which could save the breeding costs of bird parents on the nest. Nevertheless, we should also pay great attentions on the ecological traps caused by closed doors and windows, limited resources, and human interference which can decrease the birds'' breeding success.