各种环境因子对于鸟类的繁殖成效有着直接或间接的影响，而人为干扰特别是城市化在很大程度上改变了诸多环境因子。城市化对于环境因子的改变包括土地利用变化、城市热岛效应、人工夜光等方面，而这些改变引起的城市植被、栖息地质量、春季温度、资源可用性、夜间光线和物种行为（例如产卵、觅食和交流行为）方面的变化会影响到鸟类是否进行繁殖、繁殖时间窗口以及繁殖成效。

对温带和热带鸟类生活史特征进行比较有助于理解不同气候因子对于鸟类的选择压力。本研究同时监测了中国热带和温带家燕种群的繁殖活动，比较了两个种群的繁殖表现，并分别调查了天气条件对其繁殖成功率的影响。热带家燕种群的窝卵数和窝雏数都明显少于温带种群；其繁殖成功率也显著低于温带种群。日间平均气温对两个种群家燕窝卵数和窝雏数都产生负面影响；此外日间平均气温对于热带，而不是温带家燕雏鸟的存活产生负面影响。研究结果有助于我们理解广泛分布的鸟类物种在不同环境中的适应策略，以及气候变化将如何影响不同气候区域的鸟类。

候鸟通过迁徙行为往返于繁殖地和越冬地之间，候鸟不同种群间迁徙模式的形成受到不同环境因子的影响。以往研究结果表明中国西北地区的家燕种群利用西亚-东非迁飞通道和中亚迁飞通道进行迁徙。本研究结果显示，中国东部地区家燕种群利用东亚-澳大利西亚迁飞通道迁徙，其越冬地集中于东南亚地区：中国东北地区繁殖家燕迁徙多途径内陆地区到达泰国越冬；而中国华南地区繁殖家燕以岛屿为跳板进行迁徙，到达加里曼丹岛等地区越冬。不同中国家燕种群间迁徙模式差异较大，而造成这些差异的原因有待进一步探索。

Various environmental factors have a direct or indirect impact on the breeding success of birds, and human disturbances, especially urbanization, have greatly altered many of these environmental factors. The changes brought about by urbanization include land-use change, urban heat island effect (UHI), artificial light at night (ALAN), etc., which in turn affect urban vegetation, habitat quality, spring temperature, resource availability, nighttime light, and species behaviours (e.g., laying, foraging and communicating), all of which can influence bird breeding choices, optimal time windows and reproductive success.

Temperate–tropical comparisons of avian life history traits are helpful to understand the different selective pressures placed on birds by different climate factors. In this study, we monitored the breeding activities of the Barn Swallow (Hirundo rustica) simultaneously at a single tropical site and a single temperate site in China, compared the breeding performances of the two populations, and investigated the effects of weather conditions on reproductive success separately. The clutch and brood sizes of the Barn Swallow at the topical site were significantly smaller than those at the temperate site. Furthermore, the breeding success of the Barn Swallow at the tropical site was significantly lower than that at the temperate site. The mean daytime temperature had a negative effect on the clutch size and brood size at both sites; it had a negative effect on nestling survival at the tropical site, but not the temperate site. This study will help us understand the adaptation strategies of widely distributed bird species in different environments, and how climate change will affect birds in different climate zones.

Migratory birds travel between breeding and wintering sites through migration behaviour, and the formation of different migratory patterns among populations is influenced by various environmental factors. Previous research found that Barn Swallows in Northwest China make use of the West Asian-East African Flyway and Central Asian Flyway. Our study shows that Barn Swallow populations in eastern China migrate using the East Asian-Australasian Flyway with their wintering sites concentrated in Southeast Asia: swallows breeding in Northeast China migrate inland to Thailand for wintering; while those from South China use islands as stepping stones to migrate to areas like Kalimantan Island. The differences in migratory patterns among different swallow populations are significant, and further exploration is needed to understand their formation.