Migratory birds have limited potential to help plants track climate change

To track current rates of climate change, plants need to disperse their seeds towards cooler latitudes at long distances, across tens of kilometres. These distances are far beyond the standard seed-dispersal events. Juan P. González-Varo and colleagues examine whether migratory birds can help. For this to happen, the plant fruiting period needs to coincide with the migration of birds to the north. Studying seed-dispersal networks comprising 46 bird species and 81 fleshy-fruited plant species in woodland communities across Europe, and data on the fruiting period of the plants and migratory patterns of the birds, they find that most plants (86%) across communities are dispersed by birds migrating south, and only 35% are dispersed by birds migrating north, towards cooler latitudes. The latter plants have long or late fruiting periods that overlap with the northward spring migration. A small number of bird species are responsible for the majority of the northward movement.