Published online by Cambridge University Press: 20 September 2013
A range of species eating the same fruit suggests that niche overlap can occur, along with potential competition among them. To test if the overlap in the coterie of fruit-eating birds is larger than would be expected by chance, we performed a comparison with coteries generated from the use of null models. The study was carried out in an area of savanna woodland of 127 ha in Uberlândia city, Brazil. Four individuals of five zoochorous plant species were selected and 60 h of focal observation was performed on each species. We recorded species of birds that consumed fruits and the quantity of fruit removed. We used an index of Proportional Similarity (PS) between each pair of plant species, using the relative proportion of fruit taken by each bird species of each plant. The mean value of observed PS was compared with the mean PS generated from randomizations. Thirty-six bird species were recorded eating fruits in the selected plant species. The mean overlap observed (PS = 0.183) was significantly higher (P = 0.032) than the mean overlap generated by the null models (PS = 0.123). This pattern suggests that competition is not an important factor in the formation of the coteries and there is sharing of resources. The abundance of fruits offered, especially in the rainy season, and the relatively low number of frugivorous species may be factors explaining the low influence of interactions and therefore the overlap between coteries.
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