Tropical countryside riparian corridors provide critical habitat and connectivity for seed-dispersing forest birds in a fragmented landscape

Abstract

We conducted extensive mist netting and radio tracking of common frugivorous, seed-dispersing, and tropical forest-dwelling blue-crowned manakins (Lepidothrix coronata; BCMA) and white-ruffed manakins (Corapipo altera; WRMA) to study their habitat use, movements, breeding success, and seed dispersal potential in the fragmented landscape of southern Costa Rica. We obtained 1354 GPS locations from 20 BCMAs and 4040 GPS locations from 54 WRMAs we tracked. These birds were dependent on forest remnants and rarely moved through open habitats. This was more likely for WRMAs, which were slightly more tolerant of forest fragmentation. BCMAs preferred the local Las Cruces Forest Reserve and riparian corridors to smaller (<10 ha) and more isolated forest fragments. Radio tracking showed that both species used small forest fragments less than expected based on the birds' sites of capture. In general, age ratios were immature-biased and sex ratios were female-biased, especially in riparian corridors, which enabled movements across the highly deforested landscape. Average daily nest survival rate was 92.2 % for BCMA nests and 97.1 % for WRMA nests. Both species used riparian corridors 3-5 times more than expected based on land cover, utilizing these corridors for food, water, breeding, and for moving across a highly deforested landscape. Although most movements of both species were 100 m or less, some birds moved more than 600 m between observations, sometimes in only 15 min. These manakins are abundant in the forest understory and are capable of dispersing seeds more than 600 m, helping the regeneration of native vegetation. Tropical countryside riparian corridors provide critical habitat and connectivity for these common seed-dispersing forest understory birds in a fragmented landscape.