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SEED SUPPLY AS A LIMITING FACTOR FOR GRANIVOROUS BIRD ASSEMBLAGES IN THE MONTE DESERT, ARGENTINA Pedro G. Blendinger &  Ricardo A. Ojeda

Seed availability may limit the size of granivorous bird populations, particularly in desert environments. We studied seasonal and annual fluctuations in the abundance of granivorous birds at three sites in the Northern Monte, and how such changes were related to seed supply. Granivore abundance and biomass, as well as seed abundance, were greater in winter. Changes in total granivore abundance were mostly due to variations in numbers of the most mobile bird species, all of which exhibited similar patterns of variation in their abundance. Evidence suggests that, during the nonbreeding season, the most mobile species are able to track patches of high seed availability over long distances, whereas abundance of less vagile species largely depends on the local ecological conditions. Seed supply is a proximate factor that limits the abundance of granivorous birds in the Monte during the winter, but not their species richness. Granivore abundance was not correlated with seed supply in spring.


Austral Ecology (2001) 26: 413 - 422