Data from: Urbanization and artificial light at night reduce the functional connectivity of migratory aerial habitat

Flying animals use aerial habitats to forage, communicate and travel. However, human activities that fragment aerial habitat with built structures, noise, and chemical or light pollution, may limit the ability of wildlife to use airspace efficiently. Applying landscape connectivity theory to aerial habitats could reveal how long-distance migrants respond to sources of aerial habitat fragmentation along their migratory routes. Artificial light at night is a major component of urbanization that fragments dark skies across North America. Attraction of nocturnal migrants to urban light is well documented, but species-specific responses, especially throughout a full migration from breeding to wintering grounds, are not. We tested hypotheses about long-distance migratory movements in relation to artificial light using a highly nocturnal, Nearctic-Neotropical avian migrant (Eastern whip-poor-will Antrostomus vociferus). We applied a resource selection framework at multiple spatial scales to explore whether GPS-tracked birds (n = 10) responded to urbanization in general, or artificial light specifically, during migratory flights. We found little evidence of attraction to artificial light during nocturnal flights. Artificial light and urbanization were highly correlated and difficult to disentangle, but the birds generally avoided urban areas and selected dark-connected skies for travel. Migratory stopovers (locations where GPS-tracked birds (n = 20) paused for at least one night), were located almost exclusively in dark, rural areas. Our results illustrate that considering how nocturnal aerial migrants respond to both aerial and terrestrial habitat elements can improve our understanding of what may facilitate their long-distance movements.

飞行类动物依托空中生境开展觅食、交流与移动活动。然而，人类通过建造人工构筑物、产生噪声污染、释放化学污染物以及制造光污染等活动破碎化空中生境，可能会限制野生动物高效利用空域的能力。将景观连通性理论应用于空中生境研究，可揭示长途迁徙动物如何响应迁徙路线上的空中生境破碎化源。夜间人工照明是北美地区城市化进程中破碎化暗夜天空的主要因素之一。夜行性迁徙动物被城市灯光吸引的现象已有大量文献记录，但物种特异性的响应模式——尤其是从繁殖地到越冬地的完整迁徙周期内的响应——尚未得到充分研究。本研究以高度夜行性的新北区-新热带区迁徙鸟类东部鞭夜鹰（Antrostomus vociferus）为研究对象，验证了关于长途迁徙活动与夜间人工照明关联的假说。我们采用多空间尺度的资源选择分析框架，探究10只经GPS追踪的鸟类在迁徙飞行过程中，是对城市化整体产生响应，还是特异性响应夜间人工照明。研究结果显示，未发现夜行性飞行过程中鸟类受夜间人工照明吸引的显著证据。夜间人工照明与城市化程度高度相关，难以单独剥离其影响，但研究鸟类总体上会避开城市区域，选择暗夜连通的空域进行迁徙飞行。迁徙中途停歇点（即20只经GPS追踪的鸟类至少停留一晚的区域）几乎全部位于暗夜农村区域。本研究结果表明，考虑夜行性空中迁徙动物对空中与陆地生境要素的响应模式，可加深我们对促进其长途迁徙的关键因素的认知。