Fruit-eating Birds Research Articles

Negative density dependence characterizes mutualistic interactions between birds and fruiting plants across latitudes.

Negative density dependence (NDD) in biotic interactions of interference such as plant-plant competition, granivory and herbivory are well-documented mechanisms that promote species' coexistence in diverse plant communities worldwide. Here, we investigated the generality of a novel type of NDD mechanism that operates through the mutualistic interactions of frugivory and seed dispersal among fruit-eating birds and plants. By sampling community-wide frugivory interactions at high spatial and temporal resolution in Pennsylvania, Puerto Rico, Peru, Brazil and Argentina, we evaluated whether interaction frequencies between birds and fruit resources occurred more often (selection), as expected, or below expectations (under-utilization) set by the relative fruit abundance of the fruit resources of each plant species. Our models considered the influence of temporal scales of fruit availability and bird phylogeny and diets, revealing that NDD characterizes frugivory across communities. Irrespective of taxa or dietary guild, birds tended to select fruits of plant species that were proportionally rare in their communities, or that became rare following phenological fluctuations, while they mostly under-utilized abundant fruit resources. Our results demonstrate that negative density-dependence in frugivore-plant interactions provides a strong equalizing mechanism for the dispersal processes of fleshy-fruited plant species in temperate and tropical communities, likely contributing to building and sustaining plant diversity. This article is part of the theme issue 'Diversitydependence of dispersal: interspecific interactions determine spatial dynamics'.

Synthetic analysis of trophic diversity and evolution in Enantiornithes with new insights from Bohaiornithidae.

Enantiornithines were the dominant birds of the Mesozoic, but understanding of their diet is still tenuous. We introduce new data on the enantiornithine family Bohaiornithidae, famous for their large size and powerfully built teeth and claws. In tandem with previously published data, we comment on the breadth of enantiornithine ecology and potential patterns in which it evolved. Body mass, jaw mechanical advantage, finite element analysis of the jaw, and traditional morphometrics of the claws and skull are compared between bohaiornithids and living birds. We find bohaiornithids to be more ecologically diverse than any other enantiornithine family: Bohaiornis and Parabohaiornis are similar to living plant-eating birds; Longusunguis resembles raptorial carnivores; Zhouornis is similar to both fruit-eating birds and generalist feeders; and Shenqiornis and Sulcavis plausibly ate fish, plants, or a mix of both. We predict the ancestral enantiornithine bird to have been a generalist which ate a wide variety of foods. However, more quantitative data from across the enantiornithine tree is needed to refine this prediction. By the Early Cretaceous, enantiornithine birds had diversified into a variety of ecological niches like crown birds after the K-Pg extinction, adding to the evidence that traits unique to crown birds cannot completely explain their ecological success.

Synthetic analysis of trophic diversity and evolution in Enantiornithes with new insights from Bohaiornithidae

Enantiornithines were the dominant birds of the Mesozoic, but understanding of their diet is still tenuous. We introduce new data on the enantiornithine family Bohaiornithidae, famous for their large size and powerfully built teeth and claws. In tandem with previously published data, we comment on the breadth of enantiornithine ecology and potential patterns in which it evolved. Body mass, jaw mechanical advantage, finite element analysis of the jaw, and traditional morphometrics of the claws and skull are compared between bohaiornithids and living birds. We find bohaiornithids to be more ecologically diverse than any other enantiornithine family: Bohaiornis and Parabohaiornis are similar to living plant-eating birds; Longusunguis resembles raptorial carnivores; Zhouornis is similar to both fruit-eating birds and generalist feeders; and Shenqiornis and Sulcavis plausibly ate fish, plants, or a mix of both. We predict the ancestral enantiornithine bird to have been a generalist which ate a wide variety of foods. However, more quantitative data from across the enantiornithine tree is needed to refine this prediction. By the Early Cretaceous, enantiornithine birds had diversified into a variety of ecological niches like crown birds after the K-Pg extinction, adding to the evidence that traits unique to crown birds cannot completely explain their ecological success.

Dispersion of seeds at night and day in sub-Andean forests, Cueva Los Guacharos Park, Colombia

Introduction: Much has been argued about the importance of the role that different types of frugivores play as seed dispersers in plant communities, but few studies have been actually carried out. Objective: We evaluated and compared diurnal and nocturnal seed dispersal in a primary and secondary sub-Andean forest in Southern Colombia. Methods: We estimated number and biomass (kg/ha) of seeds dispersed over one year (2017) using 60 fruit traps that were checked before sunrise and before sunset for 10 continuous days every two months. Results: We found that from 1 874 dispersed seeds, 55.8 % (10.9 kg/ha) were collected during the day and 44.2 % (6.39 kg/ha) at night. There were no significant differences between diurnal and nocturnal seed dispersal in number of seeds or biomass. We also found no difference in between seed dispersal that in the primary forest and secondary forest over time. Within diurnal organisms, primates and fruit-eating birds appear to be primarily responsible for this ecosystem service during the day; while bats, birds (e.g. oilbirds), and probably primates did so during the night. Conclusions: Diurnal and nocturnal dispersal seem to be equal in terms of number and weight of seeds, but not in the similarity of dispersed plant species. It remains a challenge to recognize the relative importance of different fruit-eating organisms as seed dispersers using fruit trap methods.

Fruit Size and Structure of Zoochorous Trees: Identifying Drivers for the Foraging Preferences of Fruit-Eating Birds in a Mexican Successional Dry Forest.

Simple SummaryTropical dry forests are highly threatened by human activities such as agriculture, livestock, and selective logging. These activities have resulted in fragments of tropical dry forest under different successional stages that negatively affect the interaction between plants and fruit-eating birds. We analyzed the consumption of the fruits of zoochorous trees by birds during the dry season in a tropical dry forest and evaluated whether the horizontal and vertical structure of these trees explains fruit consumption. We also related the bird body mass and fruit size removed from zoochorous trees. We found that the tree structure can influence the visitation of fruit-eating birds, and therefore, the number of fruits consumed as the succession progresses. There was a relationship between fruit sizes and bird body mass in the successional gradient. Our results indicate that structural and fruit traits of zoochorous trees drive foraging preferences of fruit-eating birds, whose interactions in different successional stages can help to reverse the negative effects of fragmentation in tropical dry forests of the study area.Tropical dry forests (TDFs) are affected by land-use changes. These modifications impact their composition and arboreal structure, as well as the availability of food for several bird groups. In this study, we evaluated the foraging preferences in zoochorous trees of fruit-eating birds during the dry season of the year in three successional stages (early, intermediate, and mature) of TDFs in southern Mexico. The fruits of these trees are important in the diet of several birds during the dry season, a period during which food resources are significantly reduced in TDFs. We estimated foliar cover (FC) and foliage height diversity (FHD) of zoochorous trees in 123 circular plots. These variables were recognized as proxies of food availability and tree productivity. Foraging preferences were evaluated at the community level, by frugivore type, and by bird species. We evaluated the effect of the structural variables and the fruit size of zoochorous plants on fruit removal by birds and related the bird body mass and fruit size removed in the successional gradient. A total of 14 zoochorous tree species and 23 fruit-eating bird species were recorded along the successional gradient. Intermediate and mature stages showed greater fruit removal. The birds removed mainly B. longipes fruits across the three successional stages. The FHD and fruit size were important drivers in the selection of zoochorous trees and fruit removal by fruit-eating birds. Fruit size and bird body mass were positively related along the successional gradient. The results suggest that fruit removal by fruit-eating birds in the successional gradient can promote the demographic dynamics of several zoochorous tree species, especially of Bursera spp. along the TDFs.

Forest dependent birds are the main frugivorous species in mutualistic networks from the Brazilian Cerrado

ABSTRACT Not all frugivore species are equally important to the structure and maintenance of mutualistic networks and identifying the most relevant species is of great relevance to conservation ecology. Centrality metrics provide insightful information on the relative contribution of individual fruit-eating species to the topology of the networks, but there is still considerable debate on what ecological traits make frugivores highly central. We aimed to identify whether frugivory level, gape width, and forest dependency are associated with the importance of fruit-eating birds to the networks. The relative contribution of individual bird species to the networks was calculated using a combination of three centrality metrics. A mixed-effects model showed that central species in the networks were highly connected forest specialist birds. Gape width and the proportion of fruits in the diet did not explain centrality. These findings are concerning because these birds we found to be the most important species are usually highly sensitive to human disturbances and because their selective defaunation may breakdown plant-frugivore mutualistic networks. Therefore, we suggest that the conservation of seed dispersal networks in forest fragments of the Cerrado should consider protecting forest specialized frugivorous birds.

Seed-dispersing bird assemblages in riparian environments of a partially urbanized river basin, Southeastern Brazil.

Birds play a key role in ecosystem dynamics, including urban and rural areas, bringing environmental quality improvements and ecological stability. Species contribute directly to natural regeneration of vegetation and succession processes, by offering ecosystem services as seed dispersal, an important role in human-modified areas. We studied the assemblages of fruit-eating birds in riparian environments of Monjolinho basin, central São Paulo state, southeastern Brazil. Birds were recorded in 41 points distributed in riparian ecosystems alongside waterbodies, in landscapes with five types of surrounding matrices: urban, periurban, farmland, and native vegetation. We described how assemblages are structured aiming to evaluate the possible influence of seasonality and landscape type. We recorded 39 bird species that can play a role as seed-dispersers, 32 in wet season and 32 in dry season. There were no significant differences in the diversity and dominance of species between seasons considering the entire area, indicating stability of basic assemblage structure. However, total number of individuals of all species recorded in different landscapes were influenced by seasonality. Also, the composition and abundance of species significantly changed between seasons, leading to a high dissimilarity with almost 50% of the species contributing with almost 90% of the observed variation. A higher taxonomic diversity and distinctness pointed to a wider array of possible seed dispersal services in natural areas, while the lowest values of indexes were found in human-modified areas. The higher number of non-related bird species during dry season contrasted with the higher number of individuals during wet season, indicating that there is more possible ecosystem services offered by frugivorous birds in driest period of the year, while in the rainy period the carrying capacity of the riparian environments was increased.

The footprint of evolution in seed dispersal interactions.

The evolutionary stability of fruit-eating birds is linked to their role in dispersing seeds

Impacts of park roads and trails on a community of Atlantic Forest fruit-eating birds

Understanding how birds respond to road and trail disturbance is urgently needed to support conservation strategies. We aimed to assess the impacts of pathways of various widths and uses on a community of fruit-eating birds, considering that the effect of pathways should be modulated by the sensitivities of bird species. Bird data were collected over a year in four sites inside an Atlantic Forest tract in southeastern Brazil: three with different types of pathways—a main road (20 m wide, high usage), a secondary road (10 m wide—low usage), a touristic trail (2 m wide, high usage)—and a control area (no pathways). Eight sampling plots were established along with eight point-count locations at the edge of each pathway. The control area had the greatest bird diversity when more weight is assigned to equitability, followed by the area with the main road. The main road, however, had the lowest richness and abundance of large frugivores and the highest abundance of omnivores. Pathway width, usage and fruit availability were the most important components structuring the bird communities. This study revealed that the impacts of pathways in forests, particularly when paths are large and/or extensively used, might have negative consequences for local communities of fruit-eating birds. It is likely that the lower abundance of large frugivorous birds in forest tracts near pathways will affect local seed dispersal processes. Park managers should be aware and care about the management and use of pathway networks in order to maintain the services provided by frugivorous birds.

KEANEKARAGAMAN BURUNG PEMAKAN BUAH DI HUTAN KAMPUS UNIVERSITAS BANGKA BELITUNG

Avian frugivores or Fruit-eating birds have an important role in spreading plant seeds so that they can maintain stability and continuation of nature. The forest of the bangka belitung university has a vast forest area and quite high diversity. Data related to avian frugivores at Bangka Belitung University has never been published. This study aims to determine the diversity and distribution of fruit-eating birds in the Bangka Belitung University campus forest. This research was conducted at ten observation points using the Point count method. The point count method is the observation method at a predetermined location where the researcher stands at a research point with a fixed period of time. Based on the results of the research that has been conducted, there were 182 individuals belonging to 20 species and 9 families found at 10 observation points. There are three families belonging to the group of fruit-eating birds namely Columbidae, Dicaeidae and Pycnonotidae with a percentage of 77%. The most abundant fruit-eating bird species is Pycnonotus aurigaster. The highest diversity level was found at the 4th observation point, while based on the number of individuals fruit-eating birds were found at the 10th observation point. This is because the two locations have structures and compositions that can support the life of avian frugivores

A bird’s eye view: fruit grower interest in adoption of raptor nest boxes

ABSTRACT Bird damage is a serious problem for many fruit growers. Utilizing nest boxes to attract natural predators of fruit-eating birds is frequently effective in lowering bird damage, as well as increasing fruit marketability. The adoption of a conservation practice, however, depends on a grower’s level of interest. What is the level of interest in nest boxes, and how do growers perceive the influence of natural predators on the farm ecosystem? To answer these questions we conducted an online national survey of cherry and blueberry growers focusing on potential interactions between key farm variables. We found a surprising consistency in perceptions of the functioning of the farm ecosystem and a high level of agreement on how natural predators affect other production factors. Growers typically perceived nest boxes to lower bird damage and pest pressure, and to raise fruit quality and income. They also indicated a significant interest in installing nest boxes, and strong agreement that extension and outreach related to the costs, benefits and timing of implementation of nest boxes would be helpful.

Fruit and flower availability affect bird assemblages across two successional stages in the Atlantic Forest

ABSTRACT The Atlantic Forest is highly heterogeneous, with successional stages inducing shifts in food resources for birds. We investigated fruit and flower availability across two different successional stages in a continuous forest and the implications for bird communities. We sampled three sites in primary forest and three in second-growth forest. We established four plots (10 x 10 m) in each site and estimated the availability of zoochorous fruits and ornithophilous flowers and the occurrence of fruit-eating birds and hummingbirds. Unexpectedly, the availability of zoochorous fruits was similar for primary and second-growth stages, but the abundance of ornithophilous plants was higher in primary forest. Specialized frugivores were more abundant in primary forest, whereas abundance and richness of hummingbirds did not differ between the two successional stages. Frugivores responded to fruit availability in both successional stages, while hummingbirds varied according to ornithophilous plants only in the primary forest. Our results stress that the occurrence of bird species can vary according to resources availability in continuous areas, which contributes to high diversity in forests. These findings highlight the importance of preserving large continuous tracts of forests that promote a spatio-temporal distribution of resources, which maintains bird diversity and their interactions with plants.

Manipulating social information to promote frugivory by birds on a Hawaiian Island.

Animals across a range of taxa use social information when foraging. Fruit-eating vertebrates are no exception and use social information to find fruit, which may ultimately affect plant populations via seed dispersal. In many systems, mutualistic relationships between fruiting plants and frugivores are critical to maintain ecosystem functioning, especially in the tropics. On the island of O'ahu, Hawaii, USA, all native, fruit-eating birds are extinct and several plant species are experiencing reduced recruitment likely due to a lack of seed dispersal. Over the years, numerous bird species, many of which are frugivorous, have been introduced to the island. Yet, introduced birds may not recognize native fruits as a resource and social information may be needed for introduced frugivores to target and feed on native fruits. We investigated whether social information, in the form of broadcasted bird vocalizations, of introduced birds could increase visitations and more importantly frugivory on focal fruiting plants. We also tested whether the visitation rates of introduced bird species to focal plants were influenced by conspecific and/or heterospecific vocalizations. We conducted 80 playback experiments at native and introduced fruiting plants, and compared responses to silent control periods. Four times as many frugivores were detected and 10 times more frugivory events were recorded at plants with broadcasted vocalizations compared to control periods. The Japanese White-eye (Zosterops japonicus) exhibited the strongest response to both conspecific and heterospecific playbacks. White-eyes also consumed the most fruit from the widest array of plant species during trials. Introduced birds that use social information and readily identify novel resources may more effectively colonize new areas. We suggest that the White-eye's use of social information may help to support their robust population on O'ahu. Ecosystems throughout the world are affected by the loss of mutualistic relationships, many of which provide valuable ecological services. As humans continue to modify environments, novel conservation approaches may be required to maintain important ecological functions. The use of social information to facilitate frugivory may not only be important in Hawaii, but in other tropical systems where key frugivorous species are lost or abundances have been reduced.

How do fruit productivity, fruit traits and dietary specialization affect the role of birds in a mutualistic network?

AbstractMany plant traits might explain the different ecological and network roles of fruit-eating birds. We assessed the relationship of plant productivity, fruit traits (colour, seed size and nutritional quality) and dietary specialization, with the network roles of fruit-eating birds (number of partners, centrality and selectivity) in the Atlantic Forest, Brazil. We classified bird species according to their dietary specialization into three categories: obligate, partial and opportunistic fruit-eating birds. To test if network roles changed according to dietary specialization, fruit productivity and traits, we used a generalized linear model analysis. The selected 14 species of plant interacted with 52 bird species, which consumed 2199 fruits. The most central and generalist fruit-eating bird,Turdus albicolis, interacted with plants that produced more fruits, such asMiconia cinerascens, and had, on average, larger seeds, such asMyrcia splendens. The most selective birds interacted with fruits with a higher concentration of lipids and less intense colour, and plants that produced fewer fruits. Obligate fruit-eating birds, such asPatagioenas plumbea, were more selective than partial and opportunistic birds. Different plant traits are therefore related to the different network roles of fruit-eating birds in the Atlantic Forest, which are also dependent on bird dietary specialization.

Being popular or freak: how alien plants integrate into native plant-frugivore networks

The generalist diet of most frugivores opens a window of opportunity to the invasion of alien plants whit fleshy-fruits. The outcome of the new relationships between alien plants and native frugivores depends both on traits of the invaders and of the mutualist partners in the recipient community. Two contrasting hypotheses attempt to explain the integration of alien species in native communities. “Darwin’s naturalization hypothesis” proposes that alien species more different from native species are more likely to integrate in the community. The “similarity hypothesis” proposes the opposite, that alien species more similar to native species are more likely to integrate the native community. By comparing chemical and morphological traits of 12 alien and 48 native fleshy-fruited species, we tested both hypothesis as assembly rules of alien species in subtropical Andean forests. We did not find differences in most chemical or morphological traits between alien and native fruit species. The multidimensional variation of alien fruit traits was nested within that of native species. However, alien fruits tended to score high in the range of variation of native chemical traits. Accordingly, we propose the “fraction similarity hypothesis” as a main force that drive the assembly of alien species in mutualistic networks, i.e. alien species benefit from existing mutualistic interactions that involve fruit species with traits selected by the frugivores to invade native communities. The striking similarity in fruit traits between alien and native species highlights the potential role of seed dispersers as ecological filters to the invasion of alien plants. In turn, this similarity suggests that alien fruits can be functionally equivalent to native ones in terms of their interaction with fruit-eating birds.

Bird species and abundances in fruit crops and implications for bird management

Fruit consumption by birds is a costly problem in North America, yet basic information about the species and abundance of fruit-eating birds in fruit crops, and factors that influence abundance, are lacking. We conducted a study of fruit-eating birds in 'Honeycrisp' apples, blueberries, grapes, and sweet cherries in Michigan, New York, and the Pacific Northwest in 2012 and 2013. We documented the most frequently observed fruit-eating birds in each crop across our study regions, and used fruit-consumption data to identify bird species for each crop and region that have a great impact via fruit consumption. We found that American Robins (Turdus migratorius; hereafter, ‘robins’) and Cedar Waxwings (Bombycilla cedrorum; hereafter ‘waxwings’) are important fruit consumers across regions and crops, while House Finches (Haemorhous mexicanus), additionally, are important in the Pacific Northwest. We modelled and compared the abundance of fruit-eating birds in all four crops, and found that while abundance varied by region and crop, it was unaffected by heterogeneity in the surrounding land cover. Fruit growers can use information from this study to tailor bird management plans to specific crops and regions, depending on the species of concern.

Effects of Rufous-Backed Robin (Turdus rufopalliatus) on Brazilian Pepper-Tree (Schinus terebinthifolius) Seed Germination and Dispersal in a Subtropical Peri-Urban Environment

Alien invasive species pose a major threat to socioecological systems worldwide. Native avian frugivores may enhance the dispersal and germination success of exotic plants introduced for ornamental motives. In this study, we investigated the role of the native Rufous-backed Robin ( Turdus rufopalliatus) as a potential dispersal agent of the worldwide invasive Brazilian pepper-tree ( Schinus terebinthifolius). We evaluated gut transit time and mean retention time for birds feeding on this plant fruits and compared the germination rate and germination probability of intact fruits, peeled seeds, scarified seeds, and seeds from bird fecal samples. Gut transit time varied from 1.26 to 13.65 min, while mean retention time varied from 3.4 to 11.3 min. Germination rates differed between the intact seeds and the other three treatments; however, we found no differences among the germination rates of peeled, scarified, and defecated seeds. We found no differences among the seed germination probabilities of all treatments using the survival analysis; however, intact seeds presented a lower germination probability. Few studies have evaluated the role of avian frugivore’s gut transit time, mean retention time, germination rate, and germination probability on the seed germination of invasive plants. This study indicates that a native fruit-eating bird can play an important role dispersing the seeds of the Brazilian pepper-tree in an invasive range.

How Important Are Arthropods In the Diet of Fruit-Eating Birds?

ABSTRACT In most dietary studies of fruit-eating birds, sampling methods consist of direct observations of foraging and fecal sample analyses, and the consumption of resource types is measured as the percent of occurrence in diet samples, or as counts (frequency) of ingested items. Since these measures are usually biased towards the overestimation of small and abundant resources, the amount of ingested mass is a more accurate measure of the crude energy and nutrients provided by a given food source. In this study, we use direct observations of foraging behavior to describe the diet of four frugivorous-insectivorous bird species during the breeding season in Southern Yungas forests, and we compare the number of ingested items and ingested dry mass as measures of fruit and arthropod consumption. In terms of ingested food dry mass, fruit consumption represented over 95% of the diet of the four bird species. The estimated proportion of fruit in the diet differed significantly among methods in three bird speci...

Functional Equivalence in Seed Dispersal Effectiveness of Podocarpus parlatorei in Andean Fruit-Eating Bird Assemblages

Most fleshy-fruited plants establish strong local interactions with a few fruit-eating species across their distribution range, which can differ among sites and have a major impact for the plant population dynamics. In turn, human disturbances alter both the original animal assemblage with which plants interact and the outcome of the mutualistic interaction. Negative consequences of human disturbances can be weakened when different seed dispersers exert similar effects on plant populations, being functionally equivalent. To understand the consequences of variability in seed dispersers on the recruitment of a long-lived tree species, I assessed changes in the assemblages of avian dispersers of Podocarpus parlatorei in subtropical Andean cloud-forests, and how these changes affect the outcome of the interaction at different spatial scales. The seed dispersal effectiveness (SDE) concept, defined as the likelihood of a seed removed by a fruit-eating bird to be dispersed to a suitable site for seed survival and germination, provides the framework to compare the contributions of different birds to seed dispersal. I compared the SDE in two old-growth forests dominated by P. parlatorei and a human disturbed forest, and in the main habitat types of these sites. In all sites, highest SDE values were provided by gulpers that swallow the whole fleshy cone (fruit), predominantly Elaenia and Turdus species. SDE was highest in forest edges and secondary forests, and negligible in other habitats. Equivalence in SDE was relatively low both within and between forest sites. Human forest disturbance modified the functional equivalence, the generalization in mutualistic interactions and the strength of SDE. Secondary forests showed the higher SDE and the greater richness of dispersers high in SDE; as a consequence, the ecological equivalence increased in the most suitable habitat for recruitment. This could lead to greater resilience of plant populations to local extinctions of dispersers, and allows the recovery of human disturbed forests. This study shows that in the replacement of functional equivalent species, the outcomes of the interactions are strongly affected by disperser abundance and habitat use, at the expense of dispersers' trait redundancy on plant population dynamics and community structure.

Relative importance of landscape features, stand structural attributes, and fruit availability on fruit-eating birds in Japanese forests fragmented by coniferous plantations

Replacement of natural forests with plantations is causing forest loss and fragmentation worldwide. There is a great need for conservation and restoration of fauna in these fragmented forests, particularly those with special ecological functions, such as fruit-eating birds. In this 3-year study, we explored the relative importance of landscape-level and local factors for the richness and abundance of fruit-eating birds in broad-leaved forest patches scattered within a coniferous plantation in Japan. As local factors of remnant forests we included fleshy fruit availability and stand structural attributes, and then analyzed how the relative importance of these factor varies between the breeding (May–August) and non-breeding (September–December) seasons and among three bird size classes. Our results provide new insights into seasonal variations in the factors associated with bird richness and abundance and demonstrate the importance of fruit availability in the remnant forest patches. The main factors showing positive associations with bird richness/abundance were stand structural attributes (e.g., tree basal area) and landscape variables (e.g., proportion of broad-leaved forest) during the breeding season, whereas it was fruit availability during the non-breeding season, when migrating birds are dominant. We detected only minor variations in the associated factors among the three size classes. Thus, preserving continuous mature forests is of great importance for conserving breeding communities of fruit-eating birds, and maintaining fruit availability is an effective approach for supporting migrating birds during the non-breeding season. These findings are applicable to forest management aimed toward biodiversity conservation in regions being replaced or to be replaced by plantations, such as in many areas of temperate East Asia.