Great Green Macaws and the annual cycle of their food plants in Ecuador
The Great Green Macaw (Ara ambiguus) is one of the largest New World parrots and is considered endangered with extinction. Their precarious decline in western Ecuador has been attributed to food scarcity, among other pressures. To understand the effects of food abundance on macaw behavior, phenological patterns of a community of food plants were documented in a dry tropical forest in southwest Ecuador from June 1999 to May 2000. Edible biomass was estimated weekly for 100 trees representing 10 species of macaw food plants. Simultaneously, we conducted a census of macaws. Of the plants studied, little food was produced during nearly 4 consecutive months (February–May). Food availability was unrelated to macaw abundance, but was positively correlated with the amount of time macaws spent in the study area. One plant species (Cynometra bauhiniifolia) produced more food than nine other species combined and was responsible for the correlation. Additional study of macaws foraging on C. bauhiniifolia and other plant species is needed, with special attention paid to those species with both large crops and large seeds. Although the diet of Great Green Macaws remains poorly known, our study illustrates the potential importance of quantifying differences in food production by plant species consumed by threatened granivores.