2.1. Study area
The Canudos Biological Station (CBS) is managed by the Fundação Biodiversitas, and it is located in the municipality of Canudos in the northeastern micro-region of Bahia State, Brazil (09_540S, 39_070W, altitude: 400 m). The CBS experiences average annual temperatures of 24.15 _C, with November through March being the warmest season of the year and the period of greatest rainfall, although annual precipitation usually amounts to less than 400 mm (SEI, 1998).
The vegetation in the CBS is predominantly composed of shrubby hyperxerophytic Caatinga whose floristic composition has a high level of endemism in comparison to most Caatinga areas (Silva, 2007).