1.There is growing interest in understanding the functional outcomes of species interactions in ecological networks. For many mutualistic networks, including pollination and seed dispersal networks, interactions are generally sampled by recording animal foraging visits to plants. However, these visits may not reflect actual pollination or seed dispersal events, despite these typically being the ecological processes of interest. 2.Frugivorous animals can act as seed dispersers, by swallowing entire fruits and dispersing their seeds, or as pulp peckers or seed predators, by pecking fruits to consume pieces of pulp or seeds. These processes have opposing consequences for plant reproductive success. Therefore, equating visitation with seed dispersal could lead to biased inferences about the ecology, evolution and conservation of seed dispersal mutualisms. 3.Here we use natural history information on the functional outcomes of pairwise bird‐plant interactions to examine changes in the structure of seven European plant‐frugivore visitation networks after non‐mutualistic interactions (pulp‐pecking and seed predation) have been removed. Following existing knowledge of the contrasting structures of mutualistic and antagonistic networks, we hypothesised a number of changes following interaction removal, such as increased nestedness and lower specialisation. 4.Non‐mutualistic interactions with pulp peckers and seed predators occurred in all seven networks, accounting for 21–48% of all interactions and 6–24% of total interaction frequency. When non‐mutualistic interactions were removed, there were significant increases in network‐level metrics such as connectance and nestedness, while robustness decreased. These changes were generally small, homogenous and driven by decreases in network size. Conversely, changes in species‐level metrics were more variable and sometimes large, with significant decreases in plant degree, interaction frequency, specialisation and resilience to animal extinctions, and significant increases in frugivore species strength. 5.Visitation data can overestimate the actual frequency of seed dispersal services in plant‐frugivore networks. We show here that incorporating natural history information on the functions of species interactions can bring us closer to understanding the processes and functions operating in ecological communities. Our categorical approach lays the foundation for future work quantifying functional interaction outcomes along a mutualism–antagonism continuum, as documented in other frugivore faunas.

1. Co-occurring and simultaneously fruiting plant species may either compete for dispersal by shared frugivores, or enhance each other's dispersal through joint attraction of frugivores. While competitive plant–plant interactions are expected to cause the evolutionary divergence of fruit phenologies, facilitative interactions are assumed to promote their convergence. To which extent competitive and facilitative interactions among plant species with similar phenological niches are controlled by spatial variation in their local abundance and co-occurrence is poorly understood. 2. Here we test the hypotheses that when a plant species fruits in high densities, large phenological overlap with other plant species causes competition for seed dispersers owing to frugivore satiation. Conversely, we expect large phenological overlap to enhance the dispersal of a plant species fruiting in low densities through attraction of frugivores by other species in its local neighbourhood. 3. We test these predictions on plant–frugivore networks based on seed removal from 15 woody, fleshy-fruited plant species by 30 avian and 4 mammalian frugivore species across 13 study sites in Białowieża Forest, Poland. 4. A null model indicated that fruit phenologies of the regional plant assemblage were more differentiated than expected by chance. In the local networks, the tendency of plants to share frugivores increased with phenological overlap. High phenological overlap reduced the seed removal rates, interaction strength (proportion of interactions) and the number of partners of plant species fruiting in high densities. Conversely, plant species fruiting in low densities mainly profited from high phenological overlap with other species. Importantly, the sharing of mutualistic partners among co-fruiting plant species was also reflected in their co-occurrence. 5. Synthesis. Our study highlights that, in spite of the overall signal of competition, frugivore-mediated interactions among co-fruiting plant species may consistently promote the establishment and persistence of rare species through facilitation. In addition, our results suggest that, among other factors, indirect coupling of species through shared mutualistic partners might be an important determinant of plant community assembly. The coupling through shared mutualists may cause the formation of associations among co-dispersed plant species and might contribute to the coexistence of species in plant–animal mutualistic communities.