Interaction rewiring can buffer the reduction of long‐distance dispersal of seeds when large birds go extinct: an allometric perspective

Abstract

The loss of large frugivorous birds can impact their plant partners through loss of ecological services, like long‐distance dispersal of seeds. Yet, interaction rewiring, or the redistribution of interactions among remaining bird species, might help counteract the loss of long‐distance dispersal from large bird extinctions. Here, we tested if rewiring could mitigate loss of long‐distance dispersal and whether its effectiveness differed among plants with small and large fruits at different scales. We analyzed interaction data from eight Andean bird–plant seed dispersal networks, simulated extinction of large birds, allowed for lost interactions to rewire based on previous observed interactions, trait‐matching between birds and plants, and similarity in body sizes among birds (trait‐resemblance), and related changes in long‐distance dispersal to fruit‐size ratios. At the local scale, reduction in long‐distance dispersal varied among individual networks depending on whether rewiring occurred or not and the type of rewiring. At the regional scale, after aggregating results across local networks, reduction in long‐distance dispersal was between 20 and 40% for relatively small‐fruited plants (size ratio ≤ 0.25) and between 40 and 80% for relatively large‐fruited plants (size ratio ≥ 0.75) without interaction rewiring. However, with rewiring, reduction in long‐distance dispersal of smaller‐fruited plants was limited to 4% and between 4 and 10% for larger‐fruited plants. Thus, interaction rewiring can buffer losses in ecological functions, such as long‐distance dispersal, in response to large bird extinction, although relatively large‐fruited plants remain more vulnerable than smaller‐fruited plants.