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.

Long-term declines in bird populations in tropical agricultural countryside

“…3) positively and leads to long-term increases in some of the forest birds recorded there, indicating the importance of even modest efforts to keep and restore native trees in this agricultural countryside. These findings agree with our previous research showing the importance of forest remnants, riparian corridors, and individual trees for connecting this human-dominated landscape and for supporting some of the native forest bird diversity by providing breeding habitat, stepping stones for movement, habitat for surplus nonbreeders, and mosaics of different habitat types with varying phenologies of fruit, nectar, and insect production (12,13,44). Finally, populations of long-distance migratory species did better than those of the sedentary residents, in line with global assessments showing that migratory birds' mobility helps reduce their extinction likelihood (45).…”

“…As most of this landscape is already agricultural, relying on the existing forest reserves is not sufficient, and agricultural areas need to be better integrated into conservation programs. The conservation value of many tropical agricultural landscapes can be augmented substantially with modest investment and limited conflict because remnant trees, riparian strips, forest fragments, and their resident avifauna supply people and domestic animals with fruits, shade, clean water, crop pollination, and other ecosystem services (38,44,(50)(51)(52)(53). Working with individual landowners to provide them with clear incentives to conserve forest remnants should be a top priority, as exemplified by Costa Rica's successful "Payment for Environmental Services" program (54).…”

Long-term monitoring reveals an avian species credit in secondary forest patches of Costa Rica

“…These results support understandings gained from regional studies that have shown that in landscapes such as Coto Brus, where low-intensity agriculture is a significant part of the land-use matrix, forested riparian corridors (Şekercioḡlu et al, 2015), clusters of trees as small as 20 m wide (Mendenhall et al, 2011), as well as secondary forest patches, can all contribute to biodiversity (Mendenhall et al, 2014), and affect resilience, stability, and ecosystem services (Karp et al, 2011). …”

Local tropical forest restoration strategies affect tree recruitment more strongly than does landscape forest cover

“…; Sekercioglu et al . ; Zahawi, Duran & Kormann ). A second possible explanation is that we, like many field and remote sensing studies, evaluated the effect of overall forest cover, rather than presence of individual species around each plot.…”