Landscape Corridors Promote Long-Distance Seed Dispersal by Birds During Winter but Not During Summer at an Experimentally Fragmented Restoration Site

In fragmented landscapes, plant population persistence and community diversity can hinge upon plants dispersing seeds long distances between isolated patches of habitat. Landscape corridors, which connect otherwise isolated patches, have been shown to increase seed dispersal by birds moving between patch fragments. However, because bird behaviors change seasonally, the strength of this "corridor effect" may also change. We assessed the utility of corridors for promoting seed dispersal by birds during both summer and winter in a well-replicated corridor experiment conducted in early successional longleaf pine (Pinus palustris) savannah habitat at the Savannah River Site in South Carolina, USA. We used a single species of bird-dispersed fruiting plant, American black nightshade (Solanum americanum), and controlled the timing and number of fruits available to birds during summer and winter. Corridors increased long-distance seed dispersal during winter but not during summer, indicating that the effectiveness of corridors for promoting long-distance seed dispersal can depend upon plant reproductive timing and seasonal differences in bird movement. A better understanding of the seasonality of plant-animal interactions will permit better predictions about whether and how corridors provide connectivity for plants.