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1.
Animals in Southeast Asia must cope with long periods of fruit scarcity of unpredictable duration between irregular mast fruiting events. Long-term data are necessary to examine the effect of mast fruiting on diet, and particularly on the selection of fallback foods during periods of fruit scarcity. No such data is available for colobine monkeys, which may consume substantial amounts of fruits and seeds when available. We studied the diet of red leaf monkeys (Presbytis rubicunda, Colobinae) in Danum Valley, Sabah, northern Borneo, using 25 mo of behavioral observation, phenology and vegetation surveys, and chemical analysis to compare leaves eaten with nonfood leaves. The monkeys spent 46% of their feeding time on young leaves, 38% on seeds, 12% on whole fruits, 2.0% on flowers, 1.0% on bark, and 1.2% on pith. They spent more time feeding on seeds and whole fruit when fruit availability was high and fed on young leaves of Spatholobus macropterus (liana, Leguminosae) as fallback foods. This species was by far the most important food, constituting 27.9% of the total feeding time, and the feeding time on this species negatively correlated with fruit availability. Consumed leaves contained more protein than nonconsumed leaves, and variation in time spent feeding on different leaves was explained by their abundance. These results suggest that red leaf monkeys show essentially the same response to the supra-annual increase in fruit availability as sympatric monogastric primates, increasing their seed and whole-fruit consumption. However, they depended more on young leaves, in particular Spatholobus macropterus, as fallback foods during fruit-scarce periods than did gibbons or orangutans. Their selection of fallback food appeared to be due to both nutrition and abundance.  相似文献   

2.
Ecological restoration typically focuses on promoting vegetation recovery in degraded habitat or reintroducing endangered animals to enhance their regional or global persistence. Here, we argue that attention should also be devoted to vertebrate reintroductions in overhunted but floristically intact tropical forests in order to prevent insidious regime shifts in these systems. Growing evidence suggests that tropical forests deprived of seed‐dispersing animals exhibit replacement of fleshy fruiting trees by species with abiotic seed dispersal. Left unchecked, this process could eventually render the forest uninhabitable by frugivores through reduced density and diversity of their food plants. In tropical areas where hunting can be controlled, we contend that frugivore reintroduction, regulation of wild fruit harvest by humans, and outplanting of native fruiting trees should be deployed as management tools long before the systems are in need of traditional habitat restoration.  相似文献   

3.
Tropical forests show periods of scarcity and high fruit production in the same year and/or between years. Palms are an important component of Neotropical rainforests and a significant food resource for several frugivores. Therefore, their role as keystone resource may be exacerbated in highly impoverished areas. In Anchieta Island, São Paulo/Brazil, human settlements have modified and impoverished the forest, mainly through overharvesting and the introduction of exotic plants and several mammal species. We assessed the offer of fruits consumed by vertebrate frugivores at this island, the vegetation of which is belonging to the Brazilian Atlantic rainforest. We compared whether the fruiting patterns and fruit fall differ between palms and trees, and discuss the importance of palms as a food resource for frugivores and the implications for Anchieta Island conservation. Phenological patterns were seasonal for both trees and palms; however, the times of fruiting occurrence differed. Fruit fall biomass was at least twice lower than reported for other Atlantic rain forests and was also different between trees and palms. Palms contributed more than 80% of the overall fruit fall biomass. Palms may constitute an alternative food resource in periods of low fruit availability, although they do not provide resources for the entire assemblage of vertebrate frugivores. Energy-rich fruits, such as those produced by palms, may play an important role in the maintenance of frugivore populations in isolated, disturbed environments with a high density of vertebrate frugivores, low diversity of fruiting species and fruit biomass such as those found on Anchieta Island.  相似文献   

4.
Inoue  Yoichi  Sinun  Waidi  Okanoya  Kazuo 《Acta ethologica》2021,24(3):153-163
acta ethologica - In Southeast Asian forests, there are dramatic supra-annual peaks in fruit availability known as mast fruiting, followed by low-fruit periods. Gibbons are frugivorous small apes....  相似文献   

5.
Plant-frugivore networks play a key role in the regeneration of sub-tropical forest ecosystems. However, information about the impact of habitat characteristics on plant-frugivore networks in fragmented forests is scarce. We investigated the importance of fruit abundance, fruiting plant species richness and canopy cover within habitat fragments for the structure and robustness of plant-frugivore networks in a mosaic forest landscape of South Africa. In total, 53 avian species were involved in fruit removal of 31 fleshy-fruiting plant species. Species specialisation was always higher for plants than for frugivores. Both species and network-level specialisation increased with increasing fruit abundance and decreased with increasing fruiting plant species richness and canopy cover within fragments. Interaction diversity was unaffected by fruit abundance and canopy cover, but increased slightly with increasing fruiting plant species richness. These findings suggest that especially the availability of resources is an important determinant of the structure of plant-frugivore networks in a fragmented forest landscape.  相似文献   

6.
To test the hypothesis that primate populations are limited by food resources, we studied the feeding ecology of three cercopithecines and one colobine in a rain forest in central Gabon. Simultaneously, we monitored the fruiting phenology of trees and estimated the biomass of the monkey community. The Makandé Forest is dominated by Caesalpiniaceae and characterized by a lack of secondary vegetation and of trees species producing fleshy fruits. Fruit production was irregular intra- and interannually. Fruiting peaks of dry fruits (mainly Caesalpiniaceae) and of fleshy fruits occurred at the same period. However, interseasonal and interannual variability was greater in Caesalpiniaceae than in other families. As a result, the Makandé forest is subject to bottlenecks when food is scarce. On an annual basis, seeds (primarily Caesalpiniaceae) dominated the diet of all monkeys. On a seasonal basis, cercopithecines preferentially consumed fleshy fruits as long as they were available, whereas colobines increased consumption of young leaves when seed availability declined. The consumption of mature leaves was low. The monkey community biomass (ca. 204 kg/km2) is one of the lowest in Central Africa. We suggest that both cercopithecine and colobine populations are limited as a result of the combined effect of the dominance of Caesalpiniaceae, which provide dry fruits according to a mast-fruiting pattern and mature leaves of low quality, and the lack of seral successional stages, which provide fleshy fruit on a more regular pattern and leaves of better quality. During the period of food scarcity, cercopithecines should suffer from the low availability of fleshy fruit, which are their favorite food. At the same period, colobines should be limited by the low availability of edible leaves. Similar low primate biomasses are found in forests dominated by Caesalpiniaceae or Lecythidaceae in South America and in Dipterocarpaceae forests in South Asia, which suggests that their biological characteristics, in particular dry fruits and mast fruiting, are unfavorable to monkey populations. Our results confirm that habitat mosaics may support larger populations of primary consumers than homogeneous primary forests can.  相似文献   

7.
Specialized seed predators are uncommon in arboreal vertebrate assemblages, and the hypothesis that consuming seeds of immature fruits – which may be available for relatively long periods compared to mature fruit – could reduce seasonal food scarcity experienced by generalist frugivores remains largely untested. To test this hypothesis, we examined the diet and feeding ecology of bald‐faced saki monkeys Pithecia irrorata in a largely intact forest mosaic of southeastern Peru based on systematic monitoring of five habituated groups over a three‐year period and compared the relative availability of ripe and unripe fruits in their diet. Plant phenology data from individual tree crowns showed that, compared to ripe fruits, immature fruits were available in more tree species, in greater quantities, and for longer periods. Despite pronounced community‐wide seasonal changes in fruit production at our study area, feeding patterns of bald‐faced saki remained largely invariant: fruits comprised approximately 95% of the species’ monthly diet, with seeds alone accounting for 75%, with no major monthly dietary shifts. The flexible exploitation by this species of a consistently available food supply for which it faces little competition likely reduces foraging effort and consumption of less desirable foods, even during prolonged periods of overall fruit scarcity. The relative rarity of immature fruit specialists in tropical forests may reflect the fact that processing the hard pericarps and neutralizing the toxicities of immature seeds present substantial evolutionary hurdles that few arboreal vertebrate species have overcome.  相似文献   

8.
Phenology of Tree Species in Bolivian Dry Forests   总被引:2,自引:0,他引:2  
Phenological characteristics of 453 individuals representing 39 tree species were investigated in two dry forests of the Lomerío region, Department of Santa Cruz, Bolivia. The leaf, flower, and fruit production of canopy and sub–canopy forest tree species were recorded monthly over a two–year period. Most canopy species lost their leaves during the dry season, whereas nearly all sub–canopy species retained their leaves. Peak leaf fall for canopy trees coincided with the peak of the dry season in July and August. Flushing of new leaves was complete by November in the early rainy season. Flowering and fruiting were bimodal, with a major peak occurring at the end of the dry season (August–October) and a minor peak during the rainy season (January). Fruit development was sufficiently long in this forest that fruiting peaks actually tended to precede flowering peaks by one month. A scarcity of fruit was observed in May, corresponding to the end of the rainy season. With the exception of figs (Ficus), most species had fairly synchronous fruit production. Most canopy trees had small, wind dispersed seeds or fruits that matured during the latter part of the dry season, whereas many sub–canopy tree species produced larger animal– or gravity–dispersed fruits that matured during the peak of the rainy season. Most species produced fruit annually. Lomerio received less rainfall than other tropical dry forests in which phenological studies have been conducted, but rainfall can be plentiful during the dry season in association with the passage of Antarctic cold fronts. Still, phenological patterns in Bolivian dry forests appear to be similar to those of other Neotropical dry forests.  相似文献   

9.
Evidence is mounting that flowering by the mast-fruiting Dipterocarpaceae in Southeast Asia is triggered by ENSO events such that seeds are dispersed at the end of ENSO droughts. These droughts induce substantial defoliation and mortality of canopy trees, producing a favorable environment for seedling recruitment in the forest understory. Therefore, seedling release following droughts may have selected for synchronized, supra-annual fruiting in these rain forests. Currently, mast fruiting in Southeast Asia is generally regarded as an evolutionary response to seed predation by nomadic vertebrates. Separating the two causes for mast fruiting, seedling release and predator satiation, may be difficult if they are coupled in nature by ENSO droughts. Nevertheless, if the cue for masting is environmental, then the post-ENSO seedling environment should be considered a potential cause for masting, and if it operates in conjunction with predator satiation, then it may have provided the initial stimulus for supra-annual synchrony in fruiting.  相似文献   

10.
Takahashi  Kazuaki  Kamitani  Tomohiko 《Plant Ecology》2004,174(2):247-256
We investigated factors affecting seed rain beneath nine fleshy-fruited fruiting plant species growing in a 1-ha plot of planted Pinus thunbergii in central Japan. We tested whether the numbers of seeds and seed species dropped by birds beneath fruiting plants were correlated with the number of fruits removed by birds from the plants. Most of fruiting plant species with high fruit removal had significantly high seed rain. Both the numbers of seeds and seed species dropped were significantly, positively correlated with the number of fruits removed across for all fruiting plant species. Therefore, fruit removal predicted the difference among heterospecific fruiting plants in seed rain. We also tested whether the number of fruits removed from fruiting plants by birds was related with fruit crop size, fruit size, and height of the plants, and the numbers of fruits and fruit species of neighboring plants near the plants. Most of fruiting plant species with high fruit crop size had significantly high fruit removal. The number of fruits removed was significantly, positively correlated with both the fruit crop size and the number of neighboring fruits across the nine fruiting plant species. However, the effect of the neighboring fruit density on fruit removal was lower remarkably than that of fruit crop size. Therefore, fruit crop size best predicted the differences among heterospecific fruiting plants in fruit removal. We suggest that fruiting plant species with high fruit crop size and high fruit removal contribute to intensive seed rain beneath them. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

11.
Forest fragmentation, reduced forest cover, and hunting pressure are the main threats affecting animal‐mediated seed dispersal. However, their combined effects on seed dispersal rates have been simultaneously investigated only rarely, and never in Africa. We aimed to disentangle the effects of forest cover, hunting pressure, frugivore abundance, and fruit availability at the local and landscape scales on the seed dispersal rates of Staudtia kamerunensis (Myristicaceae). To estimate the percentages of seed dispersal failure (undispersed seeds), we quantitated fruit remains below fruiting trees distributed across five contrasting sites in a semi‐natural forest‐savanna mosaic in the Democratic Republic of Congo. We used statistical analyses accounting for spatial autocorrelation and found that forest cover in the surrounding landscape, hunting level, the associated abundance of dispersers, and fruit availability all had significant effects on the percentage of seed dispersal failure. The combination of high fruit availability and reduced abundance of seed dispersers could accelerate seed disperser satiation, causing the seed dispersal system to be saturated. Our study highlights how two major factors associated with anthropogenic activities, forest cover and hunting, affect seed dispersal by animals. These findings could have far‐reaching implications for our understanding of tree‐frugivore interactions and the conservation of tropical communities.  相似文献   

12.
Wild animals increasingly inhabit human-influenced environments such as forest fragments amid agricultural systems. Dietary studies provide a means of assessing wildlife responses to anthropogenic habitat changes. Chimpanzees are specialist frugivores that consume other plant parts, e.g., fibrous pith and leaves, in greater amounts during fruit shortages. I examined the plant diet and seasonal foraging strategies of chimpanzees inhabiting small forest fragments within a cultivated landscape in Uganda. I determined diet over 13 mo via systematic fecal analysis, supplemented by direct observation and feeding trace evidence. I identified important foods and examined their role as seasonal fallbacks. Diet composition and breadth were overall species typical. Chimpanzees were highly frugivorous and the fruit component of fecal samples exceeded that of nonfruit fiber in all months. Forest fruit availability fluctuated seasonally, including a 3-mo low fruiting season, when overall fruit intake declined. During this time chimpanzees pursued a mixed strategy of increasing fiber consumption and feeding more heavily on energy-rich cultivars, including those obtained through crop raiding. The data suggest that exploiting agricultural fruits helped chimpanzees maintain a fruit-dominated diet when forest fruit was scarce. No evidence suggested this disturbed forest–farm mosaic is a food-impoverished habitat for chimpanzees overall. Nevertheless, cultivar feeding creates conflict with people and the high nutritional quality of crops is likely offset by the inherent risk associated with obtaining them. This study adds to growing evidence of ecological and behavioral adaptability of Pan troglodytes in response to anthropogenic habitat alteration. Targeted conservation of key natural foods for wildlife —particularly fallbacks— would help reduce conflicts and improve the survival prospects of threatened species sharing environments with people.  相似文献   

13.
Unsustainable hunting is a threat to conservation and rural livelihoods that depend on bushmeat for food and income. To reduce the pressure on forest-dependent vulnerable species, hunting in farmland might complement offtake from forests and provide a sustainable source of bushmeat. To explore this possibility, we investigated patterns of hunting and wildlife depletion, and integration of hunting into agricultural livelihoods, in an intensively managed farm-forest mosaic landscape. Surveys were conducted across 63 households over a year in a Ghanaian cocoa-farming community surrounded by a timber production forest. The findings indicated a high level of wildlife depletion in the landscape and the local extinction of the largest species, especially in farmland. Most hunting occurred in forests and offtake from farmland was low, yet hunting in farmland was disproportionately common relative to its coverage in the landscape. Most farmland hunting was opportunistic and integrated with agricultural activities. Our findings suggest that intensively used farmland provides little opportunity to reduce hunting pressure in forests.  相似文献   

14.
Adjacent floodplain and upland tropical forests experience the same temperature and precipitation regimes, but differ substantially in plant species composition and biotic interactions because of extensive flooding. We hypothesize that flooded forests filter fruiting traits linked to seed dispersal by water and fishes, such that selection by water and fish led to (1) trees that synchronize the timing of fruiting with annual floods, and (2) the evolution of fleshy tissues on fruits to improve buoyancy and increase fruit consumption rates by fish. To test this hypothesis, we compared plant communities in seasonally flooded forests and adjacent upland forest in terms of fruiting phenology, the frequency of trees bearing fleshy fruit, and the role of fleshy tissues in buoyancy and seed viability. Beta‐diversity in this system is high, with significant differences in species composition across habitats. As predicted, the production of ripe fleshy fruits was significantly greater in flooded than upland forests during the flood season. Furthermore, we found that trees with fleshy fruit were significantly more abundant in flooded forests even though species richness of fleshy fruit‐bearing trees was proportionally similar in flooded and upland forests. Additionally, fleshy pulp increased buoyancy. Likewise, time afloat decreased for denser fruit and those with high seed to pulp ratios. In concert, these results suggest that fleshy fruits in Neotropical floodplain forests facilitated hydrochory and ichthyochory. Once established, water and fish became important agents of selection on fruiting traits.  相似文献   

15.
The spatial distribution and abundance of animals are in part determined by the distribution and abundance of their resource base. In the Central Andes of Colombia, monospecific tree plantations have been used to recover vegetative cover in watershed protection programs, but these plantations differ from natural forests in structure, composition, and resources available to wildlife. To evaluate these plantations as habitat for wildlife, we compared the diversity and abundance of understory birds, flowers, and fruits between juxtaposed 40‐yr‐old patches of exotic Chinese ash (Fraxinus chinensis) plantations and naturally regenerated forest of the same age. We observed more fruiting species in the regenerated forest, but there were no differences in total flower and fruit availability between habitat types. We also observed differences between habitats in the size of some understory shrubs, but these differences did not lead to differences between habitats in the diversity and abundance of birds. Capture rates of nectarivores correlated with resource abundance at sampling plot scale, but no such correlation was found for frugivores. Understory frugivorous birds are apparently functioning at a larger spatial scale than the patchiness created by the two habitats. Nectarivorous birds are responding to small‐scale patchiness in resource availability, but not to the different habitats. These results indicate that at small scales, the ash plantation understory provides adequate habitat for birds.  相似文献   

16.
In order to understand the ecological adaptations of primates to survive in temperate forests, we need to know the general patterns of plant phenology in temperate and tropical forests. Comparative analyses have been employed to investigate general trends in the seasonality and abundance of fruit and young leaves in tropical and temperate forests. Previous studies have shown that (1) fruit fall biomass in temperate forest is lower than in tropical forest, (2) non-fleshy species, in particular acorns, comprise the majority of the fruit biomass in temperate forest, (3) the duration of the fruiting season is shorter in temperate forest, and (4) the fruiting peak occurs in autumn in most temperate forests. Through our comparative analyses of the fruiting and flushing phenology between Asian temperate and tropical forests, we revealed that (1) fruiting is more annually periodic (the pattern in one year is similar to that seen in the next year) in temperate forest in terms of the number of fruiting species or trees, (2) there is no consistent difference in interannual variations in fruiting between temperate and tropical forests, although some oak-dominated temperate forests exhibit extremely large interannual variations in fruiting, (3) the timing of the flushing peak is predictable (in spring and early summer), and (4) the duration of the flushing season is shorter. The flushing season in temperate forests (17–28 % of that in tropical forests) was quite limited, even compared to the fruiting season (68 %). These results imply that temperate primates need to survive a long period of scarcity of young leaves and fruits, but the timing is predictable. Therefore, a dependence on low-quality foods, such as mature leaves, buds, bark, and lichens, would be indispensable for temperate primates. Due to the high predictability of the timing of fruiting and flushing in temperate forests, fat accumulation during the fruit-abundant period and fat metabolization during the subsequent fruit-scarce period can be an effective strategy to survive the lean period (winter).  相似文献   

17.
Seed dispersal by Red fox (Vulpes vulpes), Stone marten (Martes foina), and Wild boar (Sus scrofa) was analyzed in an extensively degraded mosaic landscape in Sierra Nevada (SE Spain). The main objective was to determine whether seed dispersal by mammals was related to habitat degradation within a mosaic of adjacent degraded patches mixed with native forest and thereby to determine the potential role of mammals as seed dispersers in degraded landscape units. For three consecutive years, mammal feces were collected in the fruit production period, extracting all seeds of woody species found therein and analyzing their viability. Feces were collected in three different plots for each of five different landscape units: shrubland, native forest, and dense, cleared, and fenced reforestation stands. Seeds from 16 woody species (which represent more than a half of the total fleshy‐fruited woody species available) were recorded, although some agrarian species are also introduced in a low percentage of the scats. Seeds showed a high viability rate for all dispersed species, irrespective of the mammal disperser. No differences in species composition appeared in the overall landscape units or in the seed density between degraded habitats. Due to the small patch size, the high viability of dispersed seeds, and the large home range of the large mammals, these three animal species act as efficient seed dispersers for a diverse assemblage of woody plant species regardless of the habitat type within this degradation framework. This fact has important consequences for the biodiversity recuperation in these degraded habitats, principally in pine plantations.  相似文献   

18.
Understanding the relationships among community structure, vegetation structure and availability of food resources are a key to unravelling the ecological processes that structure biological communities. In this study, we tested (i) whether the composition of small mammal communities changed across gradients in habitat quality in tropical forest fragments, and (ii) whether any observed change could be explained by the functional traits of species. We sampled 24 trapping grids in fragments of semi‐deciduous forest, in each of two 6‐month periods. We considered each trapping grid as a sampling unit, for which we collected three datasets: an environmental matrix (vegetation structure and food resource availability), the abundance of small mammal species (community structure) and a matrix of functional traits (ecological and morphological traits which express tolerance to habitat disturbance and trophic guild). We used an RLQ approach to evaluate the association between traits and environmental gradients. Forest‐specialist and scansorial–arboreal species were associated with more complex habitat that had greater litter and canopy cover and more fallen logs. In relation to trophic guilds, granivore (fruit seeds), insectivorous and omnivorous species were also associated with higher complexity habitat, while frugivores were associated with shrub cover and availability of fruits. We conclude that functional traits (habitat use, use of vertical strata and diet) provide valuable insights into the distribution of small mammals along gradients of habitat quality in tropical forest fragments. We highlight that communities studies in fragmented landscapes should investigate the different components of biodiversity not only in landscape‐scale but also in habitat scale. Abstract in Portuguese is available with online material.  相似文献   

19.
The Resplendent Quetzal (Pharomachrus mocinno) is an altitudinal migrant that nests in high elevation cloud forests and migrates toward lower areas during the summer rainy season. It has been suggested that its migratory movements are related to the abundance of ripe Lauraceae fruits. We studied the quetzal diet during two consecutive years, as well as changes in fruit abundance of the plant species on which the bird feeds at El Triunfo Biosphere Reserve, southeastern Mexico. The quetzal was observed feeding on 32 plant species; of these, 24 are new records in its diet. We chose 20 of these 32 species and studied their fruit phenology for two years in order to describe the relationship between fruit and quetzal abundance. Our results showed that quetzal abundance in the breeding area was correlated with the total number of fruiting species, whereas the correlation between quetzal abundance and the number of fruiting Lauraceae species was only marginal. Additionally, a correlation test showed that quetzal abundance was marginally correlated with total fruit availability (total no. of fruits per month); however, the correlation between quetzal abundance and the number of fruits in the Lauraceae was not significant. Our results suggest that the dynamics of food resources may be playing a major role in the quetzal's migratory behavior. Knowing the bird's diet may aid in characterizing the type of habitat adequate for its conservation. Our observations in this respect suggest that conservation efforts to preserve this bird species should concentrate on the protection of its habitat, including both breeding and nonbreeding (migration) locations.  相似文献   

20.
Wildfires are an increasing threat to tropical rainforests, yet little is known about their effects on fruit production and forest wildlife. We examined the effects of both single and recurrent wildfires on fruit production and large vertebrate abundance in a central Amazonian terra firme forest for 3 years following a large fire event. The estimated mortality of 42 and 74% of stems ≥10 cm in once- and twice-burnt forest led to a substantial loss of fruiting tree basal area (29 and 62% were lost in once- and twice-burnt forest, respectively) and crown coverage of fruiting woody lianas (89 and 97% were lost in once- and twice-burnt forest, respectively). Some important tree families producing fleshy fruits were less abundant than expected in once- and twice-burnt forest, suggesting that tree mortality was non-random in terms of species composition. Asynchronous fruit production was affected, and burnt forest transects sustained a much lower fruiting basal area, and fewer fruiting species during the dry season period of fruit scarcity. The number of fruiting trees in once- and twice-burnt forest was higher than the number predicted from actual levels of tree mortality recorded in each fire disturbance treatment, suggesting some surviving trees which may have benefited from higher irradiance levels and lower competition for resources. Many large frugivores and other vertebrate species declined in response to single fires, and most primary forest specialists were extirpated from twice-burnt forest, which sustained a higher number of species associated with second growth and other disturbed habitats.  相似文献   

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