| Popis: |
The warming climate is driving earlier spring snow melt and longer growing seasons in tundra regions of northwestern North America, thereby changing the timing of ecological processes. On Herschel Island, Yukon, Canada, we investigated changes in the migratory bird community, and the potential for phenological mismatch of egg hatching with the pulses in abundance of arthropod prey on which young birds depend for growth. We found an apparent reduction in abundance or loss of some species dependent on freshwater ponds or sparsely vegetated upland tundra. Tracking hatch dates of passerines and shorebirds along with the changes in biomass of mobile life history stages of arthropods (principally Araneae, Tipulidae, Carabidae, Muscidae, Chironomidae, Mycetophilidae, and Ichneumonidae), we found no evidence for phenological mismatch in the 2007–2009 time period. Most nests hatched, and the period of most rapid chick growth occurred, in advance of the highest availability of arthropod biomass. Shorebirds hatched significantly later than passerines, less in advance of the peak abundances of arthropods. They are most at risk of future mismatch, given likely trend to earlier onset of arthropod availability and longer migration routes. Herschel Island is a well-studied site warranting further monitoring to assess changes in the Arctic tundra ecosystem. |
