Vulnerability to global change in arctic-breeding shorebirds

这项研究计划的目的是调查北极繁殖的滨鸟对气候变化的生物后果的脆弱性。在北极繁殖的滨鸟每年从热带地区迁徙，利用加拿大北极短暂夏季出现的大量昆虫。全球变暖对北极地区的潜在影响包括：由于树木线向北移动进入苔原和湿地栖息地，栖息地发生改变；由于昆虫物候变化和北极湿地干燥，滨鸟食物群落发生变化；由于暖冬导致食肉动物群落增加，导致这些种群的死亡率降低(例如：赤狐)和在筑巢和觅食地的直接竞争，这是温带繁殖者向北迁移的结果。我们将在两个北部研究地点探讨这些后果。在马尼托巴省的丘吉尔附近，我们将研究四种北极繁殖的滨鸟，它们对栖息地变化的敏感性各不相同。半舌鸻在营养贫乏的海岸砾石栖息地筑巢，预计变化相对缓慢。Whimbrel在干燥的苔原和潮湿的莎草草地上筑巢和觅食，栖息地的灵活性可能使它们更有弹性。Dunlin只在潮湿的莎草草地筑巢，这些草地有干燥的危险，导致筑巢和觅食栖息地的丧失。红颈phalarpes在小而浅的北极池塘边缘筑巢和觅食，这些栖息地面临着干燥和灌木侵占的极端风险。我们将记录这些物种栖息地的变化是否会导致繁殖成功率降低。我们还将研究繁殖时间对幼滨鸟生长速度和存活率的影响。如果昆虫的食物出现得比迁徙的滨鸟早，那么就会出现不匹配，从而导致较低的生长速度和存活率。在努纳武特的Akimiski I.，我们还将确定杀鹿（一种常见的温带繁殖鸟类，其分布正在向北移动）是否会与觅食和栖息地要求非常相似的半平斑鸻竞争。

The objective of this research program is to investigate the vulnerability of arctic-breeding shorebirds to biological consequences of a changing climate. Arctic-breeding shorebirds migrate annually from tropical regions to make use of the abundance of insects that emerge during the Canadian arctic's short summer. Proposed consequences of global warming for the arctic region include habitat alterations due to northward movement of the tree line into tundra and wetland habitats, changes in communities of shorebird food due to changes in phenology of insects and drying of arctic wetlands, increases in predator communities as a result of milder winters that incur lower mortality on these populations (e.g., red foxes) and direct competition on nesting and foraging grounds as a result of the northward movement of temperate breeders. We will explore these consequences at two northern study locations. Near Churchill, Manitoba, we will study four species of arctic-breeding shorebirds who vary in the susceptibility of their habitats to change. The Semipalmated Plover nests on nutrient poor, gravel coastal habitats that predicted to change relatively slowly. Whimbrel nest and feed on both dry tundra and in wet sedge meadows, habitat flexibility that may make them more resilient. Dunlin nest only in wet sedge meadows that are at risk of drying, causing losses of nesting and foraging habitat. Red-necked Phalaropes nest and feed on the edges of small, shallow arctic ponds, habitats at extreme risk to drying and shrub encroachment. We will document whether changes in habitats of these species result in lower reproductive success. We will also examine the influence of timing of breeding on growth rates and survival of young shorebirds. If insect food emerges earlier than the arrival of migrating shorebirds then there can be a mismatch that will result in lower growth rates and survival. On Akimiski I., Nunavut, we will also determine whether the Killdeer, a common temperate breeding bird whose distribution is moving northward, competes with the Semipalmated Plover, a species with very similar foraging and habitat requirements.