Granivory in the Chilean matorral: Extending the information on arid zones of South America

Comparative studies of granivory intensity across different arid and semi-arid regions of the world have assumed homogeneity of conditions over large geographical areas, despite the existence of evident heterogeneities at local and regional scales. For South America, previous evidence from the Monte desert, Argentina, showed that granivory intensity is low compared with other continents and that seed removal rates by taxon (granivore ranking) are in decreasing order: ants > birds = small mammals. In this work, we examined the assumed generality of this pattern for another South American region, the Chilean matorral. We studied the differences between sparse and dense habitats of the matorral in granivory intensity throughout the year. Although total seed removal did not differ between habitats, differences among granivores did occur. Ants were the most important seed removers in both habitats, although they did not differ from birds in the sparse habitat. Further, ants were the most important seed consumers during summer, but their seed removal rare is almost negligible the rest of the year. Birds maintained an intermediate rate of seed consumption through the year. Granivory intensity by small mammals was very low in both habitats during the whole year. The granivore ranking obtained for the Chilean matorral was: ants > birds > mammals, in dense habitat; and ants = birds > mammals, in sparse matorral. Ant abundance is correlated with seed removal throughout the year. This relationship was not found in the other taxa. We discuss possible causes for the differences among habitats, taxa, and seasons, as well as distinct granivore rankings from different continents.