Spatial and seasonal variation in niche partitioning between blue manakin (Chiroxiphia caudata) and greenish schiffornis (Schiffornis virescens) in southeastern Brazil

Abstract

The diet of Chiroxiphia caudata and Schiffornis virescens were studied over three years in four forest sites in the southeastern Atlantic Forest of Brazil. Theory suggests that coexistence of similar species is possible by resource-use differences. To test this, patterns of niche overlap and niche breadth in diet were measured in different seasons and forest sites, based on fruit morphological traits and plant life forms. The results suggest seasonal and spatial variation in resource partitioning. During periods of high fruit availability, there was no evidence of fruit trait selection. In contrast, during periods of fruit scarcity in primary forests, there was evidence of niche partitioning, where C. caudata foraged for larger fruits in canopy and S. virescens searched for understory plants. The niche overlap was higher in secondary forest during periods of scarcity, when both species used small understory fruits.

Foi estudada a dieta de Chiroxiphia caudata e Schiffornis virescens durante três anos, em quatro tipos de fisionomias florestais no sudeste da Mata Atlântica, Brasil. A teoria sugere que a coexistência de espécies semelhantes é possível pelas diferenças no uso dos recursos. Assim, nós mensuramos a amplitude e sobreposição de nicho considerando a morfologia dos frutos consumidos e a forma de vida das espécies de plantas utilizadas em quatro tipos florestais e em diferentes estações. Os resultados sugerem mudanças sazonais e espaciais na partilha de recursos. Durante períodos de alta disponibilidade de frutos, não há evidências de partilha de recursos. Já em períodos de escassez de frutos nas florestas primárias, C. caudata consumiu frutos grandes presentes no dossel enquanto S. virescens utilizou os frutos pequenos do sub-bosque. Na floresta secundária, o período de escassez foi marcado por sobreposição intensa de nicho onde ambas as espécies consumiram frutos pequenos de sub-bosque.

Keywords:

• Atlantic Forest
• bird
• Brazil
• food resource
• fruit
• insect

Acknowledgements

We wish to express our gratitude to Bette A. Loiselle for her suggestions. We are indebted to Maria F. Freitas, João R. Figueiredo, Maria L. Kawasaki and Renato Goldemberg, who identified the plant species. We also thank Antonio M. Rosa and the staff of the Intervales States Park for assisting with the fieldwork and to Sandra M.J.P. Silva for helping us with fruit measurements. We appreciate the improvements in English expression made by Phil Stouffer through the Association of Field Ornithologists program of editorial assistance. This study was supported by CNPq, CAPES, FMB and is part of the BIOTA/FAPESP Program, the Virtual Institute of Biodiversity (http://www.biota.org.br) through grant no. 98/05090-6 to W.R.S., and FAPESP grant no. 98/10968-0 to E.H.