Impacts of habitat loss and fragmentation on seed dispersal by an Afrotropical bird community in an anthropogenic landscape: Insights from movement models

Abstract

Habitat loss and fragmentation can affect seed dispersal by impacting seed dispersers' habitat choices, behavior, and movement patterns. Here we studied seed dispersal by an Afrotropical bird community in an anthropogenic landscape in Kenya. We used telemetry data of six bird species, estimated their habitat choices, behavior, and movement patterns in the forest fragments and the matrix. We then integrated our model estimates into a seed dispersal simulation model with multiple artificial anthropogenic landscapes, experiencing different levels of habitat loss and fragmentation. In our simulations, we included two seed disperser groups: forest specialist and habitat generalist birds that moved in the landscape using a mixture-correlated random walk, and encamped and traveled in the different habitat types. Increased habitat loss diminished seed dispersal distances, where seeds carried by forest specialist dispersers suffered a stronger reduction in dispersal distances compared to habitat generalists, and number of seeds deposited in habitat fragments, where fewer seeds were deposited into the fragments by habitat generalist dispersers compared to forest specialists. The effects of habitat fragmentation were similar to but weaker than that of habitat loss, and most apparent at an intermediate level of habitat loss. Other seed dispersal metrics, including spatial extent of seed rain and nearest neighbor distances among seeds, did not show any strong relationships with either habitat loss or fragmentation. Therefore, movement models offer valuable perspectives on how habitat loss and fragmentation can influence seed dispersal patterns, by reliably estimating habitat choices, behavior, and movement patterns of dispersers, and potentially benefiting efforts to conserve this ecological interaction.