Large Frugivorous Birds Research Articles

Differences in bird community structure between riparian and upland zones in a New Guinean rainforest

Riparian forests serve as important habitats that enhance diversity of bird species and perform crucial ecosystem functions in tropical forest landscapes. We compared the community structure (represented by functional trait composition) and diversity (represented by Shannon index) of birds in riparian and upland zones in a semi-continuous primary rainforest in Papua New Guinea. Distance sampling was applied to provide unbiased abundance estimates. Bird community structure was examined by principal coordinate analysis of neighbour matrices (PCNM) in the Canoco 5 program. Analysis of diversity was performed using mixed-effects linear models in R 3.5.1. Species diversity was marginally higher in riparian zones (P = 0.065). Community structure differed significantly in riparian and upland zones (P = 0.008). Invertivorous and omnivorous birds preferred riparian habitats but frugivorous and nectivorous birds avoided riparian zones. Birds in riparian zones were characterised by preferences for high-density forest interior but birds in upland areas mostly occupied exposed canopy layers. Beak dimensions were greater in riparian zones but body mass, and lengths of wing and tarsus were greater in upland zones. Species found in riparian zones had greater geographical ranges than those in upland zones. Our results highlight the adaptability of a rainforest bird community to natural disturbances characterised by localised river flooding and riverbank erosion. For example, small invertivorous and omnivorous birds can navigate disturbed vegetation and exploit river-associated invertebrate food supply while moving to alternative food sources during intensive flooding. On the other hand, large frugivorous and nectarivorous birds are mostly sedentary and require an intact canopy layer for foraging, responding poorly to changes in vegetation structure. By moving beyond species-level relationships when examining bird community structure, we were able to better interpret and connect our findings with other studies on bird communities in tropical rainforest.

Negative Effects of Logging on Bird Dispersed Plants in Northern Papuan Lowland Forest, Indonesia

Many plants in New Guinean rainforest have relatively larger fruits than those in other tropical forests and may depend on large animal dispersers, but little is known about the impacts of forest disturbance, especially logging, on the species composition and abundance of these trees. In order to provide a baseline for the understanding of their vulnerability, we counted fruiting plants and measured habitat parameters in primary and human-altered habitats in the little studied lowland forest of northern Papua, Indonesia. During the surveys coinciding with peak fruit season, eighty-nine species were recorded in fruit, with 71 species in 24 families known to be consumed by birds, and most of them (97%) were trees. The diversity of bird-consumed fruiting plants differed among the habitat types and was highest in undisturbed primary forest and hunted primary forest. Secondary forests still had a high number of species and individuals but were dominated by light demanding plants and a low number of uniquely found species. Logged forest and agricultural habitats showed only a low abundance of bird-consumed fruiting plants, being about 2-3 times lower than in primary forests. Plants with large sized fruits (diam. > 20 mm) were mainly found in primary forests, confirming their importance for maintaining interactions between large frugivorous birds and plants that are of relevance for forest regeneration.

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.

Are large frugivorous birds better seed dispersers than medium- and small-sized ones? Effect of body mass on seed dispersal effectiveness.

Frugivorous birds vary in seed dispersal effectiveness (SDE) depending on their body mass. It has been suggested that large birds are more effective dispersers than small ones because they consume a large number of fruits, disperse seeds of distinct sizes, and transport seeds over long distances. Yet, few studies have evaluated the impact of body mass on SDE of birds. In this study, we compiled one database for the quantity (i.e., frequency of visits to plants and number of seeds removed per visit) and quality (i.e., germination of seeds after gut passage and gut retention time of seeds) of seed dispersal by frugivorous birds to evaluate the impact of body mass on SDE. In addition, we compiled data on plant characteristics such as life‐form, fruit type, number of seeds per fruit, and size of seed to evaluate their influence on the quantity and quality of seed dispersal. Data were analyzed with linear mixed effects models and quantile regressions to evaluate the relationship between body mass of birds and quantity, quality, and SDE, in addition to the influence of plant characteristics on SDE. The body mass of birds was negatively related to the frequency of visits to plants. Furthermore, it was positively related to the number of seeds removed per visit, although negatively related to seed size. The life‐form of plants was the only factor explaining the germination of seeds after gut passage. Yet, the body mass of birds was positively related to the gut retention time of seeds. Small and medium birds have a relatively higher SDE than large birds. These results differ from the assertion that large birds are more effective dispersers of plants. Small and medium birds are also effective dispersers of plants that should be preserved and protected from the impact of human activities.

Specialization increases in a frugivorous bird–plant network from an isolated montane forest remnant

The structure of mutualist interactions is still poorly understood in isolated remnants of montane forests. We tried to answer whether a plant–frugivore network from an isolated remnant could maintain its functional structure, despite the absence of certain species and traits. We hypothesized that a network of frugivore birds and plants from an isolated remnant would be less specialized and modular, and would show higher degree of nestedness than one from a continuous forest area. Functionally distinctive species in the networks were also identified based on analyses of the fourth-corner matrices, which cross plant and bird traits weighted by their interaction frequencies. The structure of studied networks showed a high similarity in which most interactions were performed by small generalist bird species on plant species carrying small unprotected fruits. Both networks showed similar levels of niche partitioning, although specialization and modularity increased in the isolated remnant network. Networks also showed a strong correlation between fruit weights and bird masses reflecting the functional distinctiveness of large frugivorous birds and plants with the heaviest fruits. Several large bird species were recorded in the studied networks although they contributed with a low percentage of interactions. Therefore, networks from isolated forest remnants seem resilient to the reduction of species richness due to the persistence of tolerant bird species and plant species carrying small fruits.

Effects of neighborhood on pollination and seed dispersal of a threatened palm

Changes in the spatial density and availability of resources offered by plants due to habitat fragmentation and overexploitation of the natural environment are likely to affect mutualistic interactions. We tested whether changes in the density of neighborhood conspecific and heterospecific plants and in the availability of resources influence the frequency and composition of floral and frugivorous visitors of eleven individuals of the same population of the threatened palm Euterpe edulis in Brazil. The frequency of floral visitors was positively associated with conspecific density and availability of resources. Species composition was affected by the availability of resources since some bee species were associated with palms that offered more flowers, whereas others were associated with palms that offered less. Two bee species may be able to mediate long-distance pollen-flow for E. edulis: an undetermined species of Euglossini and Apis mellifera. Frugivorous birds were not influenced by any of the factors investigated. Birds of the genus Turdus predominated in the assemblage and were responsible for most of the interactions. This is probably due to the fact that, unlike larger birds, species of Turdus are considered resilient to environmental disturbances. Due to the continuous defaunation and fragmentation of the Atlantic Forest, the number of large birds that can promote long-distance seed dispersal is declining, with implications for the genetic diversity of E. edulis. Measures to restore the population density of E. edulis will likely favor the recovery of its genetic diversity due to its high capacity for distant pollen dispersal. Recovering and protecting large frugivorous birds may also contribute to the maintenance of the population density and genetic diversity of E. edulis.

CYCAD SEED DISPERSAL: THE IMPORTANCE OF LARGE FRUGIVOROUS BIRDS

Observations of relatively large frugivorous birds, e.g. Purple-crested Turaco, feeding on cycad fruit are provided and contextualized in the important role they play in seed dispersal.

Introduction of mammalian seed predators and the loss of an endemic flightless bird impair seed dispersal of the New Zealand tree Elaeocarpus dentatus.

Understanding the mutualistic services provided by species is critical when considering both the consequences of their loss or the benefits of their reintroduction. Like many other Pacific islands, New Zealand seed dispersal networks have been changed by both significant losses of large frugivorous birds and the introduction of invasive mammals. These changes are particularly concerning when important dispersers remain unidentified. We tested the impact of frugivore declines and invasive seed predators on seed dispersal for an endemic tree, hinau Elaeocarpus dentatus, by comparing seed dispersal and predation rates on the mainland of New Zealand with offshore sanctuary islands with higher bird and lower mammal numbers. We used cameras and seed traps to measure predation and dispersal from the ground and canopy, respectively. We found that canopy fruit handling rates (an index of dispersal quantity) were poor even on island sanctuaries (only 14% of seeds captured below parent trees on islands had passed through a bird), which suggests that hinau may be adapted for ground‐based dispersal by flightless birds. Ground‐based dispersal of hinau was low on the New Zealand mainland compared to sanctuary islands (4% of seeds dispersed on the mainland vs. 76% dispersed on islands), due to low frugivore numbers. A flightless endemic rail (Gallirallus australis) conducted the majority of ground‐based fruit removal on islands. Despite being threatened, this rail is controversial in restoration projects because of its predatory impacts on native fauna. Our study demonstrates the importance of testing which species perform important mutualistic services, rather than simply relying on logical assumptions.

Aspects of the ecology of Penelope superciliaris temminck, 1815 (Aves: Cracidae) in the Araripe National Forest, Ceará, Brazil.

Guans are large frugivorous birds that inhabit Neotropical forests and play a fundamental role in seed dispersal and forest regeneration. Despite their ecological importance, the natural populations of these birds are increasingly threatened by deforestation and hunting pressure. The present study was conducted in the Araripe National Forest, Ceará (Brazil), with the objective of estimating population parameters (density and total population size) in the Rusty-margined Guan (Penelope superciliaris) and the White-browed Guan (Penelope jacucaca), as well as providing data on their feeding ecology, including seasonal variation and fruit morphology. The study was based on the monthly collection of data between November, 2011, and October, 2012. Population parameters were estimated using line transect surveys, while feeding ecology was studied by direct observation, and the collection of plant and fecal samples. The estimated population density of P. superciliaris was 19.17 individuals/km2 (CV=13.98%), with a mean of 0.13 sightings per 10 km walked. Penelope jacucaca was not encountered during the surveys. A total of 14 plant species were recorded in the diet of P. superciliaris, 12 by direct observation, and two from fecal samples. Fruit diameter varied from 6.3 ± 1.35 mm (Miconia albicans) to 29.9 ± 1.7 mm (Psidium sp.). Yellow was the most frequent fruit color (41.6%, n=5), with two species each (16.6%) providing black, green, and red fruits. Fleshy fruits of the baccate (50.0%, n=6) and drupe (33.3%, n=4) types were the most consumed. The data on population parameters and feeding ecology collected in the present study provide an important database for the development of effective management strategies by environmental agencies for the conservation of the populations of the two guan species.

Effect of forest fragmentation on bird species richness in Papua New Guinea

Tropical forests worldwide are being fragmented at a rapid rate, causing a tremendous loss of biodiversity. Determining the impacts of forest disturbance and fragmentation on tropical biotas is therefore a central goal of conservation biology. We focused on bird communities in the interior (>100 m from forest edge) of forest fragments (300, 600, and 1200 ha) in the lowlands of Papua New Guinea and compared them with those in continuous forest. We surveyed bird communities using point counts, mist-netting, and random walks, and measured habitat and microclimate characteristics at each site. We also surveyed leaf-dwelling arthropods, butterflies, and ants, and obtained diet samples from birds to examine food availability and food preferences. We recorded significantly fewer bird species per point in the 300-ha forest fragment than in other study sites. Overall, we recorded 80, 84, and 88 species, respectively, in forest fragments, and 102 in continuous forest. Frugivores (especially large frugivores) and insectivores had lower species richness in forest fragments than continuous forest. Our results did not support the food scarcity hypothesis, that is, the decline of insectivorous birds in forest fragments is caused by an impoverished invertebrate prey base. We also found no significant differences among forest fragments and continuous forest in microclimates of forest interiors. Rather, we found that microhabitats preferred by sensitive birds (i.e., 30% of species with the strongest preferences for continuous forest) were less common in forest fragments (19%-31% of points) than in continuous forest (86% of points). Our results suggest that changes in microhabitats may make forest fragments unsuitable for sensitive species. However, limited dispersal capabilities could also make some species of birds less likely to disperse and occupy fragments. In addition, impoverished food resources, size of the forest fragment, or hunting pressure could contribute to the absence of large frugivorous birds in forest fragments. The forest fragments in our study, preserved as village-based protected areas, were not large enough to sustain the bird communities found in continuous forest. However, because these fragments still contained numerous bird species, preservation of such areas can be an important component of management strategies to conserve rainforests and birds in Papua New Guinea.

Large frugivorous birds facilitate functional connectivity of fragmented landscapes

Summary Quantifying ecosystem functions in spatially explicit ways is important for management decisions in increasingly fragmented landscapes. Between‐patch dispersal of seeds by frugivores constitutes a key ecosystem function to ensure connectivity for fleshy‐fruited plants. However, to date, methodological hurdles have limited our understanding of dispersal pathways on the landscape scale. We made use of newly available tracking devices and combined movement data of 30 trumpeter hornbills Bycanistes bucinator with gut passage times and high‐resolution habitat data in a fragmented forest landscape in South Africa. We identified each potential seed dispersal path and distinguished whether potential seed transport happened to a different forest patch (between‐patch dispersal), within the same patch (within‐patch dispersal) or into the habitat matrix (failed dispersal). To quantify functional landscape connectivity, we identified all possible between‐patch connections and used graph networks to estimate landscape connectivity provided by hornbills. Although potential between‐patch dispersal events were rare (on average 7% compared to 20% failed dispersal and 73% within‐patch dispersal), hornbills could cover distances of up to 15 km. Hornbills visited over 100 forest patches and connected a habitat network with an extent of about 50 km, which increased the potential functional connectivity of the landscape more than twofold. We identified habitat patches that were critical stepping stones for seed dispersal pathways. Without these stepping stones, the network would likely disintegrate into separated components and lead to isolation of forest fragments. Synthesis and applications. We showed that large frugivorous birds can greatly improve functional connectivity for fleshy‐fruited plants across broad scales, linking habitat patches in fragmented forest landscapes. Combining high‐resolution movement and landscape data in graph networks allows identifying seed dispersal pathways and critical stepping stones in fragmented landscapes. This approach addresses the general challenge of spatially explicit mapping of ecosystem services and can be widely incorporated in reserve design and landscape‐level conservation planning.

A suite of microsatellite markers for genetic management of captive cracids (Aves, Galliformes).

Cracids are medium to large frugivorous birds that are endemic to the Neotropics. Because of deforestation and overhunting, many species are threatened. The conservation of several species has relied on captive breeding and reintroduction in the wild, but captive populations may be inbred. Microsatellite tools can permit the construction of genetic pedigrees to reduce inbreeding, but only a few loci are available for this group of birds. Here, we present 10 novel polymorphic microsatellite loci and the cross-amplification of these and of 10 additional loci available in the literature in a panel of 5 cracid species, including 3 species with high conservation concern. We provide the first polymorphic loci for the jacutinga, Aburria jacutinga (N = 8), and red-billed curassow, Crax blumenbachii (N = 9), and additional loci for bare-faced curassow, C. fasciolata (N = 8), Alagoas curassow, Pauxi mitu (N = 5), and razor-billed curassow, P. tuberosa (N = 5). The average number of alleles was 2.9 for A. jacutinga, 2.7 for C. blumenbachii, 3.5 for C. fasciolata, 2.6 for P. mitu, and 5.7 for P. tuberosa. The mean expected heterozygosities were 0.42, 0.40, 0.48, 0.37, and 0.59, respectively. The average probabilities that the set of loci would not exclude a pair of parents of an arbitrary offspring were 2.9% in A. jacutinga, 1% in C. blumenbachii, 0.5% in C. fasciolata, 0.4% in P. mitu, and 0.002% in P. tuberosa suggesting that these loci may be adequate for parentage analysis and to implement ex situ genetic management plans.

Reconciling Natural History and Species Ecology: Myristica Beddomei (Myristicaceae) in the Western Ghats, India

Natural history is an important component of any ecological or conservation research. Very often this is not given adequate attention, and observations on the genera or species are often generalized to other, supposedly similar, congeneric species. In this study, we document the natural history of fruit-frugivore interactions of Myristica beddomei (Myristicaceae) found in the mid-elevation evergreen forests of the Western Ghats, India, and determine how different these interactions are compared to other Myristicaceae species. M. beddomei has a single hard seed covered by an orange-yellow aril. Species of Myristicaceae are usually dispersed by large frugivorous birds, and also by primates in the Neotropics. In South Asia, Myristicaceae dispersal is usually by large birds such as hornbills, but our observations over several years indicate that M. beddomei is not bird-dispersed, even though some fruit traits suggest bird dispersal. Our observations suggest that obligate seed predators like macaques and squirrels can facilitate dispersal of the species. We discuss these observations and explore why such outliers might have evolved in the region

Bird functional diversity and ecosystem services in tropical forests, agroforests and agricultural areas

Although most bird species avoid agricultural areas, nearly a third of all birds regularly to occasionally use such habitats, often providing important ecosystem services like pest control, pollination, and seed dispersal. Combining literature review with large-scale analyses of the ecological characteristics of the world’s birds, I compared tropical bird species that prefer forests, agricultural areas or both, with respect to body mass, diet, range and population size, frequency, conservation status, habitat and resource specialization. Compared to primary forests, species richness of large frugivorous and insectivorous birds (especially terrestrial and understorey species) often declines in agroforests. In contrast, nectarivores, small-to-medium insectivores (especially migrants and canopy species), omnivores, and sometimes granivores and small frugivores do better, frequently by tracking seasonal resources. However, changes in guild species numbers do not necessarily translate to changes in relative abundance, biomass or function, and more studies are needed to quantify these important measures. These findings indicate that the replacement of forests and agroforests with simplified agricultural systems can result in shifts towards less specialized bird communities with altered proportions of functional groups. These shifts can reduce avian ecosystem function and affect the ecosystem services provided by birds in agroforests and other agricultural landscapes.

Seed-dispersal distributions by trumpeter hornbills in fragmented landscapes

Frugivorous birds provide important ecosystem services by transporting seeds of fleshy fruited plants. It has been assumed that seed-dispersal kernels generated by these animals are generally leptokurtic, resulting in little dispersal among habitat fragments. However, little is known about the seed-dispersal distribution generated by large frugivorous birds in fragmented landscapes. We investigated movement and seed-dispersal patterns of trumpeter hornbills (Bycanistes bucinator) in a fragmented landscape in South Africa. Novel GPS loggers provide high-quality location data without bias against recording long-distance movements. We found a very weakly bimodal seed-dispersal distribution with potential dispersal distances up to 14.5 km. Within forest, the seed-dispersal distribution was unimodal with an expected dispersal distance of 86 m. In the fragmented agricultural landscape, the distribution was strongly bimodal with peaks at 18 and 512 m. Our results demonstrate that seed-dispersal distributions differed when birds moved in different habitat types. Seed-dispersal distances in fragmented landscapes show that transport among habitat patches is more frequent than previously assumed, allowing plants to disperse among habitat patches and to track the changing climatic conditions.

Decoupling the effects of logging and hunting on an Afrotropical animal community

In tropical forests, hunting nearly always accompanies logging. The entangled nature of these disturbances complicates our ability to resolve applied questions, such as whether secondary and degraded forest can sustain populations of tropical animals. With the expansion of logging in central Africa, conservation depends on knowledge of the individual and combined impacts of logging and hunting on animal populations. Our goals were (1) to decouple the effects of selective logging and hunting on densities of animal guilds, including apes, duikers, monkeys, elephant, pigs, squirrels, and large frugivorous and insectivorous birds and (2) to compare the relative importance of these disturbances to the effects of local-scale variation in forest structure and fruit abundance. In northern Republic of Congo, we surveyed animals along 30 transects positioned in forest disturbed by logging and hunting, logging alone, and neither logging nor hunting. While sampling transects twice per month for two years, we observed 47 179 animals of 19 species and eight guilds in 1154 passages (2861 km). Species densities varied by as much as 480% among forest areas perturbed by logging and/or hunting, demonstrating the strong effects of these disturbances on populations of some species. Densities of animal guilds varied more strongly with disturbance type than with variation in forest structure, canopy cover, and fruit abundance. Independently, logging and hunting decreased density of some guilds and increased density of others: densities varied from 44% lower (pigs) to 90% higher (insectivorous birds) between logged and unlogged forest and from 61% lower (apes) to 77% higher (frugivorous birds) between hunted and unhunted forest. Their combined impacts exacerbated decreases in populations of some guilds (ape, duiker, monkey, and pig), but counteracted one another for others (squirrels, insectivorous and frugivorous birds). Together, logging and hunting shifted the relative abundance of the animal community away from large mammals toward squirrels and birds. Logged forest, even in the absence of hunting, does not maintain similar densities as unlogged forest for most animal guilds. To balance conservation with the need for economic development and wild meat in tropical countries, landscapes should be spatially managed to include protected areas, community hunting zones, and production forest.

Rapid evaluation of threats to biodiversity: human footprint score and large vertebrate species responses in French Guiana

Although there is an extensive literature demonstrating the impact of human activities on both species extinction risk and local ecological processes, the methodological tools that allow for the visualization and quantification of the intensity of the observed and forthcoming impacts are lacking. Here we propose a Footprint index for French Guiana, (northern Atlantic coast of South America) which sums up the expected and proven disturbances on biodiversity. The index was developed by superimposing geographical and human data, including human population densities, land use, settlements and camps, mining and forest activities, tracks, roads and rivers. The relevance of the index as a general measure of anthropic impact on large terrestrial fauna was estimated by investigating the structure of the large terrestrial vertebrate assemblages, including primates, large frugivorous birds, rodents and ungulates, in relation to the extent of disturbances. The abundance of large terrestrial fauna was assessed using the line-transect sampling method in 34 forest sites facing different disturbance levels, including hunting, logging and fragmentation, and consequently different footprint scores. A Self Organizing Map was used to combine species abundances and disturbance scores. It allowed us to rank species in accordance to their sensitivity towards disturbances, identifying the response of fauna to different concomitant threats. The index provided correct identification of sites with similar threats which proves it is a relevant estimator of human disturbance. In addition, the richness of animal communities and abundances of several seed dispersers and predators were negatively correlated to the index (e.g. large monkeys and frugivorous birds, r 2 = 0.49, P < 0.0001 and r 2 = 0.48, P < 0.0001, respectively), indicating its reliability in identifying areas where animal communities are disturbed. The index could, therefore, constitute a useful tool to identify areas where ecological processes supported by those species are expected to be disrupted, and where they are already disrupted. Furthermore, the footprint index can deal with lack of field data or with only partially valid information, and so may directly help land managers forecast and, hopefully, mitigate forthcoming impacts resulting from the development of human activities.

Senescence of Manilkara zapota trees and implications for large frugivorous birds in the Southern Yucatan Peninsula, Mexico

It has long been established that mature forests are mosaics of patches in different development phases but it has seldom explicitly been taken into account in ecological studies. We demonstrate here that these development phases, which are related to the population dynamics of trees, play an important role in the distribution of fauna based on observations on frugivorous birds. In an area close to the Calakmul Biosphere Reserve in Mexico, we studied the abundance of large forest bird species in relation to forest development phases, with a methodology that seems promising for ecological diagnosis and prognosis in forest management planning. Fine-scale forest mapping and bird counts were carried out in two block-transects of 40 m × 3000 m. Tree sampling in a sub-transect was used to generate population characteristics of trees. Large bird species preferred mature or senescent forest patches, whereas relatively young, growing forest patches were avoided. Important large tree species such as Manilkara zapota, Thouinia paucidentata, Guaiacum sanctum and Esenbeckia pentaphylla, characteristic of older forest patches, showed skewed size distributions indicating stress or overexploitation. The population of M. zapota, a key fruiting species that accounted for 26.5% of the total woody biomass, was most heavily affected by stress. A future collapse in the population of M. zapota, a decrease of the total area of older forest, and a decline in the abundance of large birds is likely if stress on the system continues at this level.

Rare seed‐predating mammals determine seed fate of Canarium euphyllum, a large‐seeded tree species in a moist evergreen forest, Thailand

AbstractNatural seed deposition patterns and their effects on post‐dispersal seed fate are critical to tropical tree recruitment. The major dispersal agents of the large‐seeded tree Canarium euphyllum in Khao Yai National Park, Thailand, are large frugivorous birds such as hornbills, which generated spatially heterogeneous seed deposition patterns because they regurgitated seeds at perching trees and conspecific and heterospecific feeding trees. We investigated the fate of seeds dispersed in this manner using seed removal experiments and automatic camera trapping. Seeds placed experimentally around conspecific feeding trees had higher removal rates than seeds placed elsewhere. These effects were likely mediated by two seed‐eating rodents, the Indochinese ground squirrel (Menetes berdmorei) and the giant long‐tailed rat (Leopoldamys sabanus). Consequently, the spatial patterns generated by hornbills had consequences for post‐dispersal seed fates, particularly whether or not the seeds were removed by rodents. Primary dispersal by hornbills does alter seed fate by altering the probability of rodent–seed interaction, but the ultimate impact of dispersal by hornbills will depend on how important rodent scatterhoarding is to seed germination and seedlings. Given that major seed dispersers of C. euphyllum are now absent or rare in degraded forests in tropical Asia, it is becoming increasingly important to understand the roles of scatterhoarding rodents in these altered habitats in this region.

Current knowledge and future issues for frugivory and seed dispersal by animals in Southeast Asia : special reference to large frugivorous birds and mammals

Current knowledge and future issues for frugivory and seed dispersal by animals in Southeast Asia : special reference to large frugivorous birds and mammals