Invasive birds spread native seeds: When humans introduce exotic species to sensitive ecosystems, invasion and extinction of native species often follow. The resulting ecological communities can develop unusual interactions between the survivors and newcomers. Vizentin-Bugoni et al. analyzed the structure of seed dispersal networks in Hawai'i, where native bird species have been mostly replaced by invaders. They found that the native plants now depend on the invasive birds for seed dispersal. The network of dispersal interactions is complex and stable, which are features of native seed-dispersal networks in other parts of the world. It appears that introduced species may, in some circumstances, become integrated into native ecosystems. Science , this issue p. 78

Significance: Species invasions and introductions are reshaping ecosystems around the world. In such novel ecological scenarios, it remains unclear whether crucial ecosystem functions played by lost native species may be partially or fully replaced by introduced species. We show that introduced plants and seed dispersers may take over interaction networks, playing key roles and governing network structure, with potential implications for its dynamics. The roles species play in novel networks are, however, defined by similar mechanisms that shape native-dominated communities. This indicates that the impacts of introduced species on invaded ecosystems can be anticipated based on ecological characteristics. Our results provide valuable recommendations for ecosystem management and restoration of increasingly degraded biological communities worldwide.