Spatial and temporal patterns of granivorous ant seed predation in patchy cereal crop areas of central Spain |
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Authors: | Mario Díaz |
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Institution: | (1) Departmento de Biología Animal I (Vertebrados), Facultad de Biología, Universidad Compultense, 28040 Madrid, Spain |
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Abstract: | Summary Patterns of granivorous ant seed predation in extensive cereal croplands of central Spain were investigated by measuring seed
removal rates on artificial seed patches. Sampling was designed to cope with the seasonal and daily foraging cycle of ant
colonies. Simultaneously with removal rates, I measured seed availability, habitat physiognomy at two spatial scales (landscape
and microhabitat), weather variables (temperature and rainfall), and distance to the nearest ant nest. Ant seed predation
was concentrated on shrublands, and associated with places with high covers of shrubs, chamaephytes and stones. These results
were in close agreement with those obtained by analyzing the spatial distribution of granivorous ant nests (Díaz 1991). Moreover,
there was a close relationship between seed removal rates and distance to the nearest ant nest, that fitted the predictions
of the optimal foraging model developed by Reyes-López (1987). Seasonal and daily patterns of ant foraging activity seemed
to depend more on endogenous factors than on environmental variation. I conclude that ants were not able to track the spatial
and temporal variation of their food resources in these man-modified habitats, so that their potential to interact with other
members of the granivore system is greatly reduced by human activities. |
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Keywords: | Seed predation patterns Messor capitatus Cereal croplands Environmental factors Life history constraints |
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