Canopy Frugivores Research Articles

Niche differentiation mechanisms among canopy frugivores and zoochoric trees in the northeastern extreme of the Amazon

ABSTRACT Frugivores and zoocoric trees represent an important proportion of tropical rainforest biodiversity. As niche differences favor species coexistence, we aimed to evaluate morphological and temporal niche segregation mechanisms among zoochoric trees and canopy frugivores in a tropical rainforest in the northeastern extreme of the Brazilian Amazon. We tested the effects of fruit morphology, tree size, frugivore body size and time of day on fruit consumption. We recorded the frugivore species that fed on 72 trees (44 species, 22 genera) and whether these frugivores swallowed the seeds. We monitored trees only once from 07:00 to 17:00 h between January and September 2017. We observed fruit consumption in 20 of the 72 trees. Seventy-three frugivore individuals from 22 species visited the trees. Heavier fruits were consumed by larger frugivores, while seed size was inversely correlated with frugivore size. Narrower fruits and fruits with smaller seeds had greater probability of having their seeds ingested, and larger frugivores were more prone to ingest seeds. Trees bearing fruits with smaller seeds were visited by a greater number of frugivores. Taxonomic groups differed in the time of arrival at fruiting trees. None of the evaluated variables (fruit weight and size, and seed size) affected the richness of frugivores that visited the trees. We concluded that, in the studied forest, fruit morphology (weight, size and seed size) is a niche segregation mechanism among zoochoric trees, while body size and time of day are niche segregation mechanisms among frugivores.

A new genus and species of pigeon (Aves, Columbidae) from the Kingdom of Tonga, with an evaluation of hindlimb osteology of columbids from Oceania.

The region from New Guinea through Oceania sustains the world's most diverse set of columbids. We describe osteological characters of the hindlimb (femur, tibiotarsus, tarsometatarsus) that divide the Papuan-Oceanic pigeons and doves into three groups based on functional morphology: "arboreal" (Hemiphaga, Ducula, Ptilinopus, Drepanoptila, Gymnophaps), "intermediate" (Columba, Macropygia, Reinwardtoena), and "terrestrial" (Gallicolumba [includes Alopecoenas], Trugon, Microgoura, Goura, Chalcophaps, Geopelia, Henicophaps, Caloenas, Didunculus, Otidiphaps). The arboreal and terrestrial groups are each distinctive osteologically, especially in the tibiotarsus and tarsometatarsus, which are short relative to the femur in the arboreal group, and long relative to the femur in the terrestrial group. The intermediate pigeons are more similar to arboreal than to terrestrial pigeons, but nonetheless fit in neither group. To estimate the phylogenetic relationships among or within these three groups is somewhat tentative using hindlimb osteology alone, although all five genera of arboreal pigeons have independent molecular evidence of relatedness, as do most of the genera of terrestrial pigeons. Using the hindlimb and other osteological data as a framework, we describe a new extinct genus and species of pigeon, Tongoenas burleyi, from Holocene archaeological and Pleistocene paleontological sites on six islands (Foa, Lifuka, `Uiha, Ha`afeva, Tongatapu, and `Eua) in the Kingdom of Tonga. Tongoenas was a large-sized member of the "arboreal" pigeon group, with osteological characters that relate it to Ducula, Gymnophaps, and Hemiphaga (generally canopy frugivores) rather than with the "terrestrial" pigeons (more ground-dwelling and granivorous) such as Gallicolumba, Trugon, Microgoura, Goura, etc. (others listed above). Among volant columbids, living or extinct, only the species of Goura (from New Guinea) are larger than Tongoenas. From most of the same prehistoric sites, we also report new material of the nearly as large, extinct pigeon Ducula shutleri Worthy Burley, recently described from islands in the Vava`u Group of Tonga. Thus, D. shutleri also was widespread in Tonga before human impact. The prehistoric anthropogenic loss in Tonga of Tongoenas burleyi, Ducula shutleri, and other columbids undoubtedly had a negative impact on the dispersal regimes of Tongan forest trees. At first human contact about 2850 years ago, at least nine species of columbids in six genera inhabited the Tongan islands, where only four species in three genera exist today.

Mercury bioaccumulation in tropical bats from a region of active artisanal and small-scale gold mining.

Mercury negatively affects human and animal health. Artisanal and small-scale gold mining can be a major local source of mercury contamination, especially into aquatic systems in tropical areas. Animals associated with mercury-contaminated aquatic systems are at high risk of experiencing effects of this heavy metal, but it is not clear how far the effects may extend into nearby terrestrial systems. We report mercury contamination levels in bats in agricultural areas at increasing distances from gold mining (~3-89 km of distance). We hypothesized that bat mercury concentrations would differ between feeding guilds, land use types, and be higher at sites closer to gold mining areas. We collected 112 fur samples from 30 bat species and eight guilds, and provide the first reports of concentrations in 12 species. All mercury concentrations were below the level at which health is likely to be affected (10 ppm). We found guild-influenced differences among mercury concentration levels, with the highest concentrations in aerial insectivores and carnivores, and the lowest in canopy frugivores. Our results suggest insectivorous and carnivorous bats may still be at some risk even at sites distant from aquatic mercury contamination. We did not find an effect of agricultural land-use type on mercury concentrations within species or guilds, suggesting mercury contamination did not extend to agricultural sites from areas of gold mining activities, and that these agricultural activities themselves were not an important source of mercury. We conclude bats did not demonstrate a signature of mercury risk either as a result of proximity of gold mining, or as a result of agricultural activities.

Effects of forest height and vertical complexity on abundance and biodiversity of bats in Amazonia

Anthropogenic activities have accelerated habitat change, loss, and fragmentation, threatening biodiversity over large portions of the tropics. The resulting anthropogenically created landscape mosaics often include forests of different successional stages or that have experienced different levels of anthropogenic use, which affect the physical structure of the forest (e.g., forest height, vertical complexity of vegetation). These physical characteristics of forests may affect the abundance and biodiversity of forest inhabitants, and obscure effects of landscape changes (e.g., percent forest cover) on animal species. Because bats are ecologically diverse and include seed dispersers, pollinators, and top predators, they contribute to the structure and function of forests, and directly affect forest integrity and regeneration. Thus, understanding how variation in the vegetative structure of forests affects the abundance and biodiversity of bats may provide important information to effectively manage and conserve forest fragments. We surveyed bats at 24 sites in the southern Brazilian Amazon, and quantified vegetation structure (density, height, and basal area of trees, density of understory, and canopy openness). Using generalized linear mixed-effects models, we tested simple relationships of each structural characteristic with community- (taxonomic and phylogenetic dimensions of biodiversity), guild-, and population-level attributes of bats. Models for total abundance, taxonomic biodiversity (species diversity and dominance), and phylogenetic diversity were significant, increasing with tree height and basal area, and decreasing with canopy openness. At the population level, abundances of frugivores (Carollia perspicillata, Rhinophylla pumilio, Artibeus planirostris, A. obscurus, A. lituratus, Uroderma bilobatum) and nectarivores (Lonchopylla thomasi, Glossophaga soricina) were related significantly to vegetation structure. Abundances of some understory frugivores exhibited negative relationships with tree height, choosing younger forests, whereas abundances of canopy frugivores were highest in closed canopy forests. Of the nectarivores, L. thomasi was more abundant in older forests (negative relationship with density of trees), whereas G. soricina was more abundant in areas with low canopies and low basal area (i.e., earlier successional forest). Consequently, effective management of forest fragments should include consideration of local forest age and vegetation structure, as well as forest connectivity and patch size. In general, protecting areas with large trees and closed canopies enhances the persistence of pollinators and seed dispersers.

Landscape composition is more important than landscape configuration for phyllostomid bat assemblages in a fragmented biodiversity hotspot

Human-modified landscapes are composed of different types of land covers in differing proportions (landscape composition), and each with differing spatial physiognomy (landscape configuration). Unfortunately, the information on the relative impact of these two components of landscape structure on biological assemblages is scarce, but urgently needed to improve conservation strategies. We assessed the relative influence of the composition (landscape forest cover and matrix composition) and configuration (degree of forest fragmentation and forest edge density) of 100-ha and 500-ha landscapes on the abundance, diversity, and evenness of phyllostomid bat assemblages in the Lacandona rainforest, Mexico. We assessed the complete bat assemblage and frugivorous bats separately, and we grouped frugivores into understory foragers and canopy foragers. Landscape forest cover was the main predictor of the complete bat assemblage, positively affecting species diversity, particularly the number of rare species. Thus, community evenness decreased in landscapes with higher forest cover. Although weaker, species diversity was positively related to fragmentation and negatively associated with edge density. Landscape composition also was relatively more important than configuration for frugivores. The number of common and dominant frugivorous species and the abundance of understory frugivores increased in landscapes with lower forest cover and dominated by secondary forests in the matrix. The abundance of canopy frugivores showed the opposite response. Thus, to preserve bat assemblages and their important functional roles, conservation initiatives should prioritize a reduction in deforestation and the increase of secondary forests in the matrix. Maintaining all remaining forest patches is needed to favor landscape complementation and supplementation dynamics.

Ground-Vegetation Clutter Affects Phyllostomid Bat Assemblage Structure in Lowland Amazonian Forest.

Vegetation clutter is a limiting factor for bats that forage near ground level, and may determine the distribution of species and guilds. However, many studies that evaluated the effects of vegetation clutter on bats have used qualitative descriptions rather than direct measurements of vegetation density. Moreover, few studies have evaluated the effect of vegetation clutter on a regional scale. Here, we evaluate the influence of the physical obstruction of vegetation on phyllostomid-bat assemblages along a 520 km transect in continuous Amazonian forest. We sampled bats using mist nets in eight localities during 80 nights (3840 net-hours) and estimated the ground-vegetation density with digital photographs. The total number of species, number of animalivorous species, total number of frugivorous species, number of understory frugivorous species, and abundance of canopy frugivorous bats were negatively associated with vegetation clutter. The bat assemblages showed a nested structure in relation to degree of clutter, with animalivorous and understory frugivorous bats distributed throughout the vegetation-clutter gradient, while canopy frugivores were restricted to sites with more open vegetation. The species distribution along the gradient of vegetation clutter was not closely associated with wing morphology, but aspect ratio and wing load differed between frugivores and animalivores. Vegetation structure plays an important role in structuring assemblages of the bats at the regional scale by increasing beta diversity between sites. Differences in foraging strategy and diet of the guilds seem to have contributed more to the spatial distribution of bats than the wing characteristics of the species alone.

Chaco Chachalaca (Ortalis canicollis, Wagler, 1830) feeding ecology in a gallery forest in the South Pantanal (Brazil).

Cracids are generalist frugivores, which often exploit plant food resources such as flowers and leaves, mainly when fruit production declines. The Chaco chachalaca (Ortalis canicollis) is the most abundant cracid in the Pantanal (Brazil), and particularly common in the gallery forests. However, the factors related to their occurrence in this habitat type are unclear. In this study I describe the feeding habits and feeding niche breadth fluctuations of the Chaco chachalaca in relation to food resources abundance and diversity at the Miranda river gallery forest (Southern Pantanal). I also analyzed the relationships between Chaco chachalacas feeding activity and food resources abundance. This parameter (flowers and fruits) exhibited significant seasonal differences of abundance in which flowers were plentiful at the end of the dry, while fruits were abundant during the early wet season. However, food resources diversity to Chaco chachalacas exhibited no seasonal difference. Their feeding activity paralleled the availability of food resources, so that when some items were massively available an enhanced number of Chaco chachalacas foraged in the gallery forest, particularly during the prolonged dry season when they extensively used flowers and Genipa americana fruits. In fact, the Chaco chachalaca feeding niche breadth value presented low values in this period, while high values were common in the rest of the year. The flexible diet of this cracid, potentially favors their year round presence in the gallery forest, mainly during the prolonged dry season when the propensity for famine might be high. Since the Chaco chachalaca is among the largest and most abundant canopy frugivores in the gallery forest, it may contribute to forest regeneration, an underscored role due to the impact of annual floods and meandering dynamics on tree loss.

Does the Bananaquit Benefit Commensally from Parrot Frugivory? An Assessment Using Habitat Quality

AbstractHow strong‐beaked frugivores such as parrots affect other frugivores is poorly understood. This study quantitated six indices of habitat quality for the facultatively frugivorous Bananaquit (Coereba flaveola) using two habitat types and three treatments of habitat quality, namely old growth forest versus citrus orchards in Dominica, the latter habitat type with and without parrot frugivory. The study also controlled for elevation, rainfall and citrus fruit maturity. The results indicate that both the quantity of parrot frugivory and fruit maturity at the time of frugivory influenced the habitat quality for Bananaquits. Their abundance was higher, individuals stored more fat, and parasite loads were lower on farms with more parrot frugivory. Fruit quality mediated the influence of the quantity of parrot frugivory insofar as Bananaquit body condition was tightly correlated with the fruit chemistry at the time of frugivory or harvest. This study provides empirical evidence of a commensal association and underscores the important ecological role of Neotropical psittacines as mediators of habitat quality for other animal. The findings further suggest that loss of these apex consumers may have triggered previously unappreciated trophic cascades, particularly in island ecosystems lacking large mammalian canopy frugivores.

Availability of Food for Frugivorous Bats in Lowland Amazonia: The Influence of Flooding and of River Banks

In Neotropical forests fruits are key resources for a great diversity of vertebrates, including many frugivorous bats, but little is known about the factors that determine their availability. We studied forest inundation and river banks as determinants of the spatial variation in the availability of fruits for bats in lowland Amazonia. We sampled the bat assemblage composition, fruit availability, and bat diet in terra firme upland forest and in two types of flooded forest — várzea and igapó. Two distinct frugivore bat guilds were found in both terra firme and flooded forests: (1) canopy frugivores, feeding mainly on Ficus and Cecropia, and (2) understorey frugivores that feed mainly on Vismia and Piper. Fruits consumed by the canopy guild were more abundant in the flooded forests — particularly in the nutrient-rich várzea, but those dominating the understory guild diet were most abundant in terra firme. Availability of both fruit genera most consumed by the canopy guild was greater along river banks than in the forest matrix. For the understory guild, the greater abundance of Vismia along river banks was compensated for by a higher availability of Piper in the matrix. In conclusion, both factors influence the availability of fruits, although differently for the canopy and understory guilds. The resulting differences in fruit abundance may explain variations in bat assemblages of the different forest types. River banks play a particularly important role in providing food for bats of both guilds, but are under particularly heavy human pressure.

Bird Abundances in Primary and Secondary Growths in Papua New Guinea: A Preliminary Assessment

Papua New Guinea is the third largest remaining area of tropical forest after the Amazon and Congo basins. However, the growing intensity of large-scale slash-and-burn agriculture and logging call for conservation research to assess how local people's traditional land-use practices result in conservation of local biodiversity, of which a species-rich and diverse component is the avian community. With this in mind, I conducted a preliminary survey of birds in small-scale secondary plots and in adjacent primary forest in Wanang Conservation Area in Papua New Guinea. I used mist-netting, point counts, and transect walks to compare the bird communities of 7-year-old secondary growth, and neighboring primary forest. The preliminary survey lasted 10 days and was conducted during the dry season (July) of 2008. I found no significant differences in summed bird abundances between forest types. However, species richness was higher in primary forest (98 species) than in secondary (78 species). The response of individual feeding guilds was also variable. Two habitats differed mainly in presence of canopy frugivores, which were more abundant (more than 80%) in primary than in secondary forests. A large difference (70%) was found also in understory and mid-story insectivores. Species occurring mainly in secondary forest were Hooded Butcherbird ( Cracticus cassicus), Brown Oriole ( Oriolus szalayi), and Helmeted Friarbird ( Philemon buceroides). Examples of primary forest species were Red-bellied Pitta ( Pitta erythrogaster), Little Kingfisher ( Alcedo pusilla), and Zoe's Imperial Pigeon ( Ducula zoeae). My results suggest that changes in bird assemblages occur even in relatively undisturbed landscapes in response to small-scale shifting agriculture that is crucial for local people's livelihood; it also seems that traditional land use by local people favors the persistence of a rich bird species pool in the forested and traditionally managed landscape.

Bird species richness in a Bornean exotic tree plantation: A long-term perspective

To provide sustainable income from forestlands, large areas in the tropics are planted with “agricultural” trees, such as oil palm and rubber, and “industrial” trees, such as Acacia mangium and Gmelina arborea. To examine how native forest birds use such plantations, we surveyed in 2005 the avifauna at Sabah Softwoods, a plantation in southeastern Sabah, Malaysian Borneo. We focused on A. mangium, Albizia ( Paraserianthes falcataria), oil palm ( Elaeis guineensis), and logged native forest, and compared our results to those of a study conducted at the same plantation in 1982. The number of forest species in the industrial groves did not change dramatically between 1982 and 2005, even though the trees had been cropped several times and the plantation was, by 2005, completely surrounded by cleared land and far removed from primary forest. However, as is common in logged or isolated forests throughout the world, certain primary forest groups (e.g., muscicapine flycatchers) have been extirpated from the entire plantation area. The industrial groves also lacked some larger species of kingfisher, woodpeckers, and canopy frugivores. Nevertheless, numerous primary forest taxa (ca. 50% of species) were found in mature industrial tree groves. Albizia attracted the most species of birds, followed closely by Acacia. Both tree types underpinned relatively complex secondary forests that attracted forest birds. In contrast, younger groves of Acacia and Albizia held mainly open country and scrub species. Oil palm, as a remarkably simple and unusual habitat, attracted few bird species. Sustained occurrence of forest birds in all groves of exotic trees at Sabah Softwoods was substantially enhanced by the relatively rich avifauna of the logged native forest remaining in substantial stands throughout the plantation.

Increasing the value of bird-habitat studies in tropical forests: choice of approach and habitat measures

AbstractAn important component of many conservation studies is the assessment of bird-habitat relationships, but limited resources often lead to constraints on study design, quality and quantity of bird data, and restrict the number and types of habitat variables gathered. The aim of this study was to identify habitat features that were both relatively easy and quick to collect and powerful in identifying bird-habitat relationships. We also discuss some issues with our study and alternative approaches that may help in future bird-habitat studies in tropical forests. Twenty-four habitat measures representing geographical (e.g. altitude, topography, X and Y coordinates), vegetation structure (e.g. tree sizes), and tree floristics (abundance of 28 indicator tree species) features were collected in association with bird presence/absence data from point transects within a 1,500 ha Philippine lowland forest. We used hierarchical partitioning of regression analyses to assess which of these geographical and structural variables along with four floristics axes derived from DECORANA were the most important variables for explaining the occurrence of individual bird species and guilds. The ten most powerful variables for a range of bird species included seven geographical and three floristic variables, while the ten least important were all structural variables. There were differences in importance of individual variables across guilds, with, for example, floristics very important in canopy frugivores, and geographical variables more important for upperstorey gleaning insectivores. We stress the importance of geographical variables in linking birds to habitat at this local scale, but also suggest that efforts are made to collect some floristics data, perhaps a subset of species that represent resources for birds (e.g. Ficus spp.), people's use of the forest (e.g. dipterocarps), and indicators of forest type. While the habitat variables and approach in this study adequately identified bird-habitat relationships for most species, we suggest improvements and alternative methods that may improve results in other studies.

Species richness and structure of three Neotropical bat assemblages

We compared the assemblages of phyllostomid bats in three Neotropical rainforests with respect to species richness and assemblage structure and suggested a method to validate estimates of species richness for Neotropical bat assemblages based on mist-netting data. The fully inventoried bat assemblage at La Selva Biological Station (LS, 100 m elevation) in Costa Rica was used as a reference site to evaluate seven estimators of species richness. The Jackknife 2 method agreed best with the known bat species richness and thus was used to extrapolate species richness for an Amazonian bat assemblage (Tiputini Biodiversity Station; TBS, 200 m elevation) and an Andean premontane bat assemblage (Podocarpus National Park; BOM, 1000 m elevation) in Ecuador. Our results suggest that more than 100 bat species occur sympatrically at TBS and about 50 bat species coexist at BOM. TBS harbours one of the most species-rich bat assemblages known, including a highly diverse phyllostomid assemblage. Furthermore, we related assemblage structure to large-scale geographical patterns in floral diversity obtained from botanical literature. Assemblage structure of these three phyllostomid assemblages was influenced by differences in floral diversity at the three sites. At the Andean site, where understorey shrubs and epiphytes exhibit the highest diversity, the phyllostomid assemblage is mainly composed of understorey frugivores and nectarivorous species. By contrast, canopy frugivores are most abundant at the Amazonian site, coinciding with the high abundance of canopy fruiting trees. Assemblage patterns of other taxonomic groups also may reflect the geographical distribution patterns of floral elements in the Andean and Amazonian regions. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 94, 617–629.

Adjusting count period strategies to improve the accuracy of forest bird abundance estimates from point transect distance sampling surveys

Although point transect distance sampling methods have become widely used in surveys of forest birds, there has been no attempt to tailor field methods to maximize the accuracy of abundance estimates by minimizing the effects of violations of the method's critical assumptions, which are: (1) birds at distance 0 m are detected with certainty, (2) birds are detected at their initial location and (3) distances to objects are measured accurately. We investigate the effects on abundance estimates for Philippine forest birds of varying the count period from 2 to 10 min, and of including and excluding a pre‐count settling down period. Encounter rates were highly sensitive to count period length but density estimates from 10‐min count periods were, on average, only 13% higher than those from 2‐min periods, and in several cases were actually lower than those from periods of 6–8 min. This was because birds tended to be recorded at greater distances from the recorder as the count period went on, thus ‘stretching out’ detection functions while having little effect on detection rates close to the recorder. For some bird groups, including canopy frugivores and upperstorey gleaning insectivores, density estimates were more than twice as high without than with a settling down period. We suggest that movement away from the recorder is more common than attraction to the recorder, and that unless pilot studies show otherwise, similar studies should not use a settling down period for surveying many species. Count periods that maximized probability of bird detection close to the central point while minimizing the unwanted effects of bird movement during the count period were: 4 min for omnivores, 6 min for nectarivores and upperstorey gleaning insectivores, 8 min for understorey insectivores and canopy frugivores, and a full 10 min for sallying insectivores, ground‐dwellers, carnivores and coucals/koels. We use the results to suggest ‘group‐specific’ count period regimes that could help maximize the accuracy of density estimates from similar studies of tropical forest birds.

The value of primary, secondary and plantation forests for Amazonian birds

Secondary forests and exotic tree plantations are rapidly expanding across tropical landscapes, yet we currently have a very poor understanding of the value of these human-dominated forest landscapes for biodiversity conservation. Mist netting, point counts and transect walks were used to compare the bird communities of these habitats and neighboring primary forest in north-east Brazilian Amazonia. The extensive spatial scale of plantations and second-growth in our study area enabled us to implement a robust replicated design, with survey plots approximately two to three orders of magnitude larger than most previous studies of land-use change in the tropics, thus minimising the influence of the surrounding landscape. Species richness was highest in primary forest and lowest in Eucalyptus plantations, and community turnover between habitats was very high whether based upon matrices of relative abundance or species presence–absence data, and for both point count and mist net data. Monthly line-transect censuses conducted over an annual cycle showed an increase in the detection of canopy frugivores and seed predators during the peak of flower and fruit availability in primary forest, but failed to suggest that second-growth or Eucalyptus stands provide suitable foraging habitat at any time of the year. The conservation value of both secondary forest and plantations was low compared to conclusions from previous studies. Our results indicate that while large-scale reforestation of degraded land can increase regional levels of diversity, it is unlikely to conserve most primary forest species, such as understorey insectivores and canopy frugivores.

As aves da Reserva Florestal do Morro Grande (Cotia, SP)

Um total de 198 espécies de aves foi registrado na Reserva Florestal do Morro Grande. O levantamento foi realizado entre os anos de 2001 e 2003, utilizando-se métodos de amostragem qualitativos e quantitativos (redes de neblina e pontos fixos). O número de espécies registrado através dos métodos quantitativos foi menor do que o número total de aves presentes na Reserva, sendo 98 espécies registradas nos pontos fixos e 46 nas redes de neblina. Apesar das diferenças, os dois métodos se mostraram eficientes na detecção de padrões de distribuição das aves. Existe uma grande heterogeneidade da avifauna na Reserva, sendo que as diferenças mais marcantes são entre os trechos de matas primárias e secundárias. As matas primárias são mais ricas e apresentam muitas espécies exclusivas. No entanto, mesmo entre os trechos de mata secundária também existem diferenças. Apesar de ser uma grande área de mata contígua às matas da Serra de Paranapiacaba, muitas aves parecem já ter desaparecido da Reserva, como as sensíveis à caça e os frugívoros de dossel. Mesmo assim a Reserva do Morro Grande abriga uma alta diversidade de espécies, com muitas aves endêmicas e ameaçadas. A manutenção e recuperação de suas matas representam importantes ações para a conservação das aves da Mata Atlântica.

Effects of hunting on guianan forest game birds

To assess the effect of on-going and of previous or near by hunting pressure on game birds in a neotropical rain forest (French Guiana), I compared species abundances between six hunted and disturbed areas, seven non-hunted and pristine areas and eight intermediate areas, undisturbed and not currently hunted, but formerly hunted or close to current hunting areas. I recorded all birds detected within 100 m-wide strip transects, walked at random through every forest type all day long. The frequency of records per 10 h and flock sizes on each transect were averaged over all surveys in each study site (N = 3025 h). Censused groups included terrestrial (tinamous, woodquails, curassow and trumpeter) and arboreal species (guans, macaws, parrots, toucans), but not waterbirds. The abundance of all game birds was higher in non-hunted than in hunted areas, though not always significantly for secretive understorey species (tinamous, guans, wood-quail) or canopy frugivores (parrots, macaws, toucans). The Black Curassow and Gray-winged Trumpeter exhibited the highest and most consistent increases (7–10-fold) and more so between intermediate and non-hunted sites than between hunted and intermediate sites. The mean flock size also increased along the hunting gradient, especially in flocking species (macaws, parrots, trumpeter). Low reproductive rates and/or seasonal movements may explain that hunting pressure could still be felt after hunting has ceased or when it persists only away from a given area. Such a persistent effect would affect some populations in small protected areas.

Bird Community Responses to Disturbance in a Forestry Concession in lowland Bolivia

Bird community characteristics of three sites with different levels of disturbance were studied using transect surveys during the dry season in a subtropical humid forest in Bolivia. One area had been unintentionally burned 4 years prior and selectively harvested (DIS) 1 year prior to sampling. A second area had been selectively harvested 1 year prior to sampling and had no recent history of fire (HAR). Species richness, as assessed by species–time curves and rarefaction, was higher in both altered areas than in undisturbed forest (INT). In general, frugivores and omnivores were more abundant in both altered areas compared to intact forest. Canopy frugivores, understory omnivores and multiple-strata omnivores were most abundant in HAR. Canopy frugivores, near-ground insectivores, understory and multiple-strata omnivores were least abundant in INT, although INT had the highest abundances of canopy insectivores and near-ground omnivores. Richness and abundance of widespread species with low habitat specificity was higher in both areas that experienced disturbance compared to intact forest. Differences in bird community structure between disturbed and intact forest at this site are attributed primarily to the addition of widespread species with less narrow habitat requirements, and possibly to changes in the distribution of different food types.

Morphology and flight manoeuvrability in New World leaf‐nosed bats (Chiroptera: Phyllostomidae)

AbstractThe relationship between wing morphology and ability to manoeuvre through an obstacle course was examined in five species of bats in the Neotropical family Phyllostomidae. These species represent a range of morphologies and feeding adaptations: Tonatia silvicola, a surface‐gleaning insectivore; Artibeus jamaicensis and A. literatus, canopy frugivores; and Carollia perspicillata and C. castanea, understory frugivores. Bats of known morphology were presented with three different obstacle arrangements chosen in random order. In order to control for wing span, spacing between obstacles was scaled to the wing span of the individual (1×, 0.75×, 0.5× the wing span of the bat). Performance was measured as the number of times a bat hit an obstacle hard enough to deflect it. Morphological variables were analysed using principal components analysis and were summarized by the first two principal components (PC): PC 1, ‘size’, with which size‐related variables were strongly, positively correlated; PC 2, ‘camber’, on which variables associated with maximum depth of wing camber weighted most heavily. Obstacle course performance was significantly correlated with both size and camber at all obstacle spacings: larger bats hit more obstacles, even though obstacle spacing was scaled to wing span, and bats with better ability to camber wings hit fewer obstacles. These results show that bat species that forage in more cluttered habitats are more likely to be small in size and/or have wings able to produce the high camber necessary to maintain lift at low flight speeds.

Responses of an avian community to rain forest degradation

Cumulative impacts of logging and road building in a previously undisturbed tract of tropical rain forest in French Guiana were assessed by random sampling of the bird community and 1-km2 plot counts of diurnal raptors. Similar surveys were carried out during road construction and 15 years later within 5km of the road and were also compared with the undisturbed bird community of a nearby primary forest. The main disturbance was the change in forest structure brought about by logging and secondarily the road opening, the roadside second growth and the depletion of large vertebrates by hunting pressure. The responses of different bird guilds were highly divergent according to their natural habitat requirements, their diet and their vulnerability to hunting. They resulted in a moderate decrease in overall species richness and equitability. All species pooled, the abundance of 118 species was lowered, that of 45 species did not change appreciably and 89 were favored or even appeared. The guilds most affected were those with large body sizes, from terrestrial foragers to canopy frugivores, mostly by hunting, and the open understorey specialists, notably large insectivores and mixed flock members, because of changes in forest structure after logging. The guilds favored by logging and road opening were many of the hummingbirds, upper canopy frugivores and omnivores, and gap, edge or low secondary growth specialists. Recommendations to minimize the negative consequences of human exploitation in rain forests include reducing the width of deforested roadsides to no more than 10–15m on either side, implementing much more careful logging practices and strongly limiting hunting pressure in newly opened areas.