Summer Rainfall and Winter Sparrow Densities: A Test of the Food Limitation Hypothesis
1982; Oxford University Press; Volume: 99; Issue: 1 Linguagem: Inglês
10.2307/4086028
ISSN1938-4254
AutoresJohn B. Dunning, James H. Brown,
Tópico(s)Wildlife Ecology and Conservation
ResumoWe used published data on winter sparrow densities (from Christmas Bird Counts) and summer precipitation to test the hypothesis that local densities of wintering sparrows in southeastern Arizona are affected by the abundance of food. Our analyses rest on the assumption, justified by previous studies, that the abundance of seeds available to wintering granivorous birds is correlated with the quantity of rainfall the previous summer. Our results strongly supported two a priori predictions: (1) the density of sparrows should be positively correlated with summer rainfall, and (2) the density of individual sparrow species should be positively correlated with the total density of all other sparrow species. Our findings provide further evidence that winter finch populations are food-limited and suggest that interspecific competition may be important in at least some avian communities.
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