Coupled Dynamics of Lemmings and Long-Distance Migratory Birds

Abstract

The reproductive success of tundra-nesting birds exhibits considerable variation. It has been proposed that this variation is the result of predators switching from lemmings to bird eggs and nestlings in years after the lemming population has crashed. In a recent study (Blomqvist et al. 2002) that included a long time series of data of tundra-breeding birds, two species of geese and two species of waders, were analyzed. Several results support the ``bird-lemming{''} hypothesis: (1) measurements of reproductive output correlates with lemming abundance, (2) measurements of reproductive output exhibit 3-year cycles as does the lemming abundance index, (3) adult waders migrate earlier in years when nest predation is expected to be most intense, (4) timing of migration of adult waders exhibits 3-year cycles. An attempt to test the impact of climate on reproductive success or survival of juveniles was unsuccessful.