Foraging ecology of parrots in a modified landscape: Seasonal trends and introduced species

We studied the diet and foraging ecology of a community of six psittacines in western Costa Rica. All had a varied diet with clear seasonal changes in preferred food items, mostly due to changes in plant phenology. There was a significant relationship between parrot mass and food types: larger-bodied parrots consumed more seeds and smaller-bodied parakeets consumed more fruit pulp. Leaves, bark, and lichen were also consumed by most psittacines. Most parrots consumed more plant species in the dry season when food availability was at its peak. Levins' niche breath showed varying levels of diet specialization among species and, for some species, variation among seasons. There was less similarity in seasonal psittacine diets when compared to overall diets. Scarlet Macaws (Ara macao) under study were captive raised and released which may have contributed to their narrow diet breadth as they may have lacked the knowledge or experience to exploit additional food sources. Non-native and cultivated species comprised 76% of the diet of Scarlet Macaws, and averaged 28% for all other species. This suggests that foraging parrots may have increased conflicts with humans as landscapes become increasingly modified. Forest restoration strategies should augment the abundance of food species consumed when overall food supply is at its annual low.