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Summary 1.Seed dispersal by frugivores is the basis for regeneration of fleshy-fruited plants in forest ecosystems. Previous studies have reported a decrease in forest specialist frugivores due to logging and forest edges. Forest generalists appear less sensitive and may even increase at forest edges. Such changes in the abundance of frugivores may have consequences for consumer/resource ratios and competition in plant-frugivore networks. 2. Optimal foraging theory predicts an increase in dietary specialization of animals at low consumer/ resource ratios due to reduced competition. A decrease in forest specialists in logged forests should cause decreased consumer/resource ratios, increased dietary specialization and reduced redundancy, whereas an increased abundance of forest generalists at edges may compensate for a loss of specialists. 3. In Europe's last old-growth lowland forest (Białowie_ za, Eastern Poland), we recorded fruit removal by frugivores from fleshy-fruited plant species in the interior and at edges of logged and old-growth forests for 2 consecutive years. 4. The abundance of forest generalists increased at forest edges, whereas specialists were unaffected. Conversely, logging resulted in a decrease in abundance of forest specialists but had no effect on the abundance of generalists. Accordingly, consumer/resource ratios increased from interior to edges and were reduced in the interior of logged forests compared with the interior of old-growth forests. As predicted by optimal foraging theory, a decrease in consumer/resource ratios coincided with increased dietary specialization and a loss of redundancy in the interior of logged forests. Despite low dietary specialization, redundancy was reduced at forest edges as forest generalists dominated plant-frugivore interactions. 5. Synthesis. We show that a shift in frugivore assemblages at forest edges and increased dietary specialization of frugivores in the interior of logged forests involved a loss of redundancy compared with continuous old-growth forests. This suggests that seed dispersal services in secondary forest habitats depend on an impoverished subset of dispersal vectors and may suffer reduced adaptive potential to changing environmental conditions. Thus, our study highlights the value of old-growth forests for the conservation of frugivore-mediated seed dispersal processes.

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Species’ functional traits set the blueprint for pair-wise interactions in ecological networks. Yet, it is unknown to what extent the functional diversity of plant and animal communities controls network assembly along environmental gradients in real-world ecosystems. Here we address this question with a unique dataset of mutualistic bird–fruit, bird–flower and insect–flower interaction networks and associated functional traits of 200 plant and 282 animal species sampled along broad climate and land-use gradients on Mt. Kilimanjaro. We show that plant functional diversity is mainly limited by precipitation, while animal functional diversity is primarily limited by temperature. Furthermore, shifts in plant and animal functional diversity along the elevational gradient control the niche breadth and partitioning of the respective other trophic level. These findings reveal that climatic constraints on the functional diversity of either plants or animals determine the relative importance of bottom-up and top-down control in plant–animal interaction networks.

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. 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. 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 hypothesized a number of changes following interaction removal, such as increased nestedness and lower specialization. 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, specialization and resilience to animal extinctions and significant increases in frugivore species strength. 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.

Summary1. 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 Białowie_ za 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 cofruiting 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 cofruiting 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.

Wildlife damage to human property threatens human-wildlife coexistence. Conflicts arising from wildlife damage in intensively managed landscapes often undermine conservation efforts, making damage mitigation and compensation of special concern for wildlife conservation. However, the mechanisms underlying the occurrence of damage and claims at large scales are still poorly understood. Here, we investigated the patterns of damage caused by brown bears Ursus arctos and its ecological and socio-economic correlates at a continental scale. We compiled information about compensation schemes across 26 countries in Europe in 2005-2012 and analysed the variation in the number of compensated claims in relation to (i) bear abundance, (ii) forest availability, (iii) human land use, (iv) management practices and (v) indicators of economic wealth. Most European countries have a posteriori compensation schemes based on damage verification, which, in many cases, have operated for more than 30 years. On average, over 3200 claims of bear damage were compensated annually in Europe. The majority of claims were for damage to livestock (59%), distributed throughout the bear range, followed by damage to apiaries (21%) and agriculture (17%), mainly in Mediterranean and eastern European countries. The mean number of compensated claims per bear and year ranged from 0·1 in Estonia to 8·5 in Norway. This variation was not only due to the differences in compensation schemes; damage claims were less numerous in areas with supplementary feeding and with a high proportion of agricultural land. However, observed variation in compensated damage was not related to bear abundance. Synthesis and applications. Compensation schemes, management practices and human land use influence the number of claims for brown bear damage, while bear abundance does not. Policies that ignore this complexity and focus on a single factor, such as bear population size, may not be effective in reducing claims. To be effective, policies should be based on integrative schemes that prioritize damage prevention and make it a condition of payment of compensation that preventive measures are applied. Such integrative schemes should focus mitigation efforts in areas or populations where damage claims are more likely to occur. Similar studies using different species and continents might further improve our understanding of conflicts arising from wildlife damage