Habitat use and seed dispersal effectiveness by oilbirds (Steatornis caripensis) in the southern Andes of Colombia

The behavior of frugivorous animals (e.g. movement patterns) usually influence plant populations through processes of seed dispersal, however, there are still systems that need to be described and analyzed. This study analyzed information on the habitat use and seed dispersal effectiveness for a population of oilbirds (Stearornis caripensis) in the southern Andes of Colombia. To determine what structural and floristic factors influence habitat choice (such as fragmentation, forest cover, and elevation) we analyzed the frequency of use of different land covers by three oilbirds with GPS devices attached. We also used data from 25 vegetation plots (0.1 ha) to characterized the most frequent sites visited by oilbirds. In addition, geographic information systems were used to evaluate the degree of fragmentation and forest cover in the region, and compare it with the sites frequently used by oilbirds. Seed dispersal effectiveness was assessed from the quantity of dispersed seeds dispersed at the main roosting cave, the estimated number of seeds reaching adequate habitats for establishment, germination rates of dispersed seeds, and estimates of seed and seedling survival (from literature review). Oilbirds prefer to visit dense forests, avoid high altitudes and visit both continuous and disturbed forests. The most frequently visited sites have a high proportion of plants known to be consumed by oilbirds. No relationship was found between seed dispersal effectiveness (SDE) and the mean elevation range of the plant species, but SDE was higher when oilbirds were out of the nesting period. The results suggest that the degradation of oilbird populations may confer negative conservation implications on plants (especially large seeded species). Although oilbirds visit secondary forests infrequently ( < 10%), they perform a unique ecological role in dispersing seeds to remote locations, including dense forests, as well as degraded and fragmented environments. Oilbirds may be incorporated in ecological restoration programs that aim to sustainably manage biodiversity.