Vulnerability to global change in arctic-breeding shorebirds

点击翻译按钮获取中文摘要

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.