Weak evidence of carry-over effects of overwinter climate and habitat productivity on spring passage of migratory songbirds at a northern stopover site in Ontario

Reduced rainfall in tropical regions decreases the availability of food resources for overwintering songbirds, with negative impacts on their body condition. Increasingly dry conditions at tropical wintering sites as a result of climate change may impact the ability of temperate-breeding songbirds to prepare for and execute their spring migration. We studied the carry-over effects of natural climatic fluctuations created by the El Niño Southern Oscillation (ENSO) in tropical overwintering areas on seven long-distance migratory songbirds at a Canadian stopover site. We used the Normalized Difference Vegetation Index as a proxy for tropical habitat productivity and resource availability and a 34-year bird banding dataset from Long Point, Ontario, Canada to assess migration timing and stopover body condition. To increase our ability to detect potential carry-over effects, we employed a novel approach of using recent migratory connectivity studies to restrict the wintering ranges to areas m...

热带地区降雨量减少会降低越冬鸣禽的食物资源可获得性，对其身体状况产生负面影响。气候变化导致热带越冬地干旱状况加剧，可能影响温带繁殖鸣禽准备和执行春季迁徙的能力。我们研究了热带越冬区厄尔尼诺-南方涛动（El Niño Southern Oscillation, ENSO）引起的自然气候波动对加拿大中途停留点七种长距离迁徙鸣禽的滞后效应。我们使用归一化差异植被指数（Normalized Difference Vegetation Index）作为热带栖息地生产力和资源可获得性的替代指标，并利用加拿大安大略省朗波因特34年的鸟类环志数据集评估迁徙时间和中途停留时的身体状况。为了提高检测潜在滞后效应的能力，我们采用了一种新方法——利用近期迁徙连通性研究将越冬范围限制在...