Search

Savanna ecosystems are maintained by fires with a fire-adapted biota, and savannas occur in Amazonia in patches surrounded by tropical forest. Different fire regimes can generate structurally diverse vegetation, and the composition of savanna bird assemblages is known to be closely related to vegetation structure. However, long-term approaches and interaction of fire with other environmental factors need to be explored for the better understanding of the effects of fire on birds. In an Amazonian landscape composed by savanna and forest, we investigated the effects of different fire regimes in a 12-ha area in three periods through 23 years. We also examined the effects of frequency and extent of fires, tree cover, and distance to forest on bird composition in twelve 3.7- ha savanna plots. Birds were surveyed with mist-nets and species were classified as to their habitat use by comparison of registers in forest and savanna plots through visual/acoustical surveys. After 13 years without fire, many forest species colonized the area and some savanna species were lost. Fire regime affected avifauna assemblages. The avifauna was sensitive to the occurrence of fires. After one fire event in a plot that had not burned for 12 years, some savanna species returned. These results highlight the effects of the fire regime on birds and indicate that many savanna bird species depend on the occurrence of regular fires. more...

The mechanisms governing assemblages and the maintenance of biodiversity in tropical environments remain disputed. Two hypotheses were tested for waterbird communities in the Amazonian wetlands: (1) waterbird richness and gradients in species composition differ in Amazonian white- and black-water lakes, and are influenced by variation in lake-to-lake differences in characteristics including area, perimeter, shape, and isolation; (2) waterbird assemblages are also influenced by neighboring water-body richness (rivers, channels, ponds, and other lakes) and location of lakes in the wetlands in relation to the tributary rivers. Bird surveys were conducted using a boat in 264 lakes stretching over 1,000 km of Amazon River floodplains. The hypotheses were tested using multivariate ordination analysis, followed by multiple linear models, to evaluate how bird richness (number of species) and species composition (which species) are affected by abiotic lake characteristics. At a local scale, lake perimeter, area, and shape affected local heterogeneity in species composition of the bird community, whereas at larger scales differences among sites in water-body richness and black- and white-water types were associated with variation in waterbird richness. The patterns found indicate that lake limnological attributes influence local heterogeneity in waterbird communities within Amazonian floodplains. more...

Butterflies have evolved a variety of defensive traits against visually hunting predators, especially insectivorous and omnivorous birds. However, few bird species that attack and feed on butterflies in the Neotropical region are known. Here we present a list of 36 species belonging to 15 bird families observed to attack butterflies in different sites of Central and South America. In addition to comments on the birds involved, we also indicate which bird families are expected to reveal new butterfly predators. more...

Adult plants incapable of producing viable offspring inflate our perception of the size of population distribution. We propose that species occurrence is limited to a subset of the environmental gradient and that it changes as ontogenetic development progresses. Moreover, fruit production is associated with site-specific environmental conditions. We sampled 2988 adult individuals from nine palm species in 30 plots (40 × 250 m) and used a larger data set including 42 other plots distributed along a continuous topo-edaphic gradient in a terra firme forest near Manaus, Brazil. Five out of nine palm species were more restricted to a sub-section of the topo-edaphic gradient in the adult-size phase. More specifically, reproductive individuals of species Attalea attaleoides and A. microcarpa had even more restricted distributions than adult-sized, non-reproductive plants. Successive environmental filtering and competition probably acting through selective mortality led to increasing habitat restriction, with reproductive adults being restricted to a smaller part of the region than juveniles and adults. Water availability and nutrients limited both the ability to produce fruits and the amount of fruit production. Previous studies have reported stronger habitat associations for older plants than for seedlings or juveniles, but we show here that some species are more restricted at their reproductive stage. Plant specializations to local conditions may be more common than currently acknowledged, and a significant portion of individuals in a population might represent sinks. Such strong environmental limitations of reproductive plants should also be considered in management of species with economic value and in conservation planning. more...

Because of recent increases in populations of Black Vultures (Coragyps atratus) and Turkey Vultures (Cathartes aura), vulture-human conflicts have become more common. We can begin to mitigate these conflicts by first identifying what attracts these birds. We investigated the use of thermal power plants (TPPs) by vultures in Manaus, Central Amazon, Brazil, from February–September 2012, and monitored six TPPs throughout urban areas. We visited each TPP six times at three intervals. At all TPPs, we observed vultures use artificial thermals as a way to gain elevation during flight. The largest number of vultures was observed in TPPs near feeding sites and roosting areas. We recorded the largest concentration of vultures in the late afternoon. We observed an interaction effect between site and time, where TTPs near roost sites had more vultures early morning and late afternoon, while TPPs near feeding sites had more vultures at mid-day. Our results show that vultures intensively use TPPs to aid their ... more...

The main hypothesis is that waterbird richness in Amazonian lakes differs between white- and black-waters, and has gradients in species com- position relating to lake-to-lake differences in shape, depth, water transparency, habitat richness, and pro- ductivity. I tested a complementary hypothesis that bird assemblages respond to variations in lake char- acteristics over a regional scale, and to neighboring aquatic components, called water body richness, including rivers, channels, and ponds. Bird surveys were conducted by circumnavigating 70 lakes along 1,000 km of Amazon River floodplains. To test these hypotheses, a non-metric multiple-dimensional scal- ing ordination complemented by multiple linear models was used to determine relationships between bird richness and assemblage composition, and biotic and abiotic lake characteristics. At a local scale, lake shape, water transparency, and trophic status influence bird assemblages. At a regional scale, differences among sites in water body richness, produced by Amazon River tributaries, and the two water types, are determinants of variation in composition of waterbird assemblages. The results indicate that waterbird assemblage composition within Amazonian flood- plains does result from links in processes operating at both spatial scales as predicted by neutral theory or influenced by local ecological factors as predicted by niche theory. more...

The mechanisms that maintain palm species diversity in tropical rain forests are still debated. Spatial variation in forest structure produces small-scale environmental heterogeneity, which in turn can affect plant survival and reproductive performance. An understanding of how palms respond to variation in forest heterogeneity may help to explain the diversity and structure of their assemblages. We used multivariate ordination statistics and multiple linear models to analyse how palm assemblages are affected by forest structure and landscape features in central Amazonia. In 72 (250×4 m) forest plots distributed over an area of 64 km2, we recorded all seedling and adult palms, and measured topographic and soil variables, and components of forest structure and tree abundance. We found 16976 adults and 18935 seedlings of 46 palm species and five varieties including two morphological forms making a total of 50 botanical entities. Results show that landscape features (altitude, slope, proportions of soil sand and clay) and various components of forest structure (such as degree of forest openness, abundance of forest trees, logs and snags, and leaf litter mass), influence spatial variation in richness, abundance and species composition of palms, creating ecological gradients in palm community composition. Despite the statistically significant effects of environmental variables, most species occurred throughout the full range of the ecological gradients we studied, indicating that there is either relatively weak niche specialization in the palms, or that the competition between the species is mediated by diffuse demographic processes that cannot be evaluated only through studies of species distributions. more...

The distribution and abundance of Yellow-billed Terns (Sternula superciliaris), Large-billed Terns (Phaetusa simplex) and Black Skimmers (Rynchops niger) were estimated, and the effects of habitat features on site occupancy by colonies of these three species nesting in the Anavilhanas Archipelago, Amazonas, Brazil, were examined. Individuals were recorded on beaches during the 2008 and 2009 breeding seasons, with 26 (2008) and 30 (2009) potential nesting beaches (sites) surveyed. In both years, one site included 28% of all the Yellow-billed Terns, while two sites included 65% of all the Large-billed Terns. Site occupancy, the probability that a site is occupied (range ψ), was moderate to low for all three species, but higher for Yellow-billed Terns (0.58–0.63) than for Large-billed Terns (0.40–0.50) and Black Skimmers (0.23–0.54). Yellow-billed and Large-billed terns and Black Skimmers generally nested on larger beaches on islands that had little vegetative cover and that were exposed to open wa... more...

We investigated the effects of forest fragmentation on bird assemblages in an Amazonian savannah landscape with forest fragments that have been isolated for more than 100 years. The study was conducted in areas surrounding the village of Alter do Chão (2°31'S, 55°00'W), Santarém, Brazil. Bird surveys and measurements of tree density were undertaken in 25 areas, with 19 plots in forest fragments of different sizes and six in an area of continuous forest. Data on forest-fragment size, perimeter, and isolation were obtained from a georeferenced satellite image. Variation in number of bird species recorded per plot was not related to vegetation structure (tree density). The number of bird species recorded per plot increased significantly only with fragment area, but was not influenced by fragment shape or degree of isolation, even when considering species from the savannah matrix in the analysis. Fragments had fewer rare species. Multivariate ordination analyses (multiple dimensional scaling, [MDS]) indicated that bird species composition changed along a gradient from small to large forest fragments and continuous-forest areas. In the Amazonian savannah landscapes of Alter do Chão, the organization and composition of bird assemblages in forest fragments are affected by local long-term forest-fragmentation processes. Differences in the number of bird species recorded per plot and assemblage composition between forest fragments and continuous forest were not influenced by forest structure, suggesting that the observed patterns in species composition result from the effects of fragmentation per se rather than from preexisting differences in vegetation structure between sites. Nevertheless, despite their long history of isolation, the forest fragments still preserve a large proportion (on average 80%) of the avifauna found in continuous-forest areas. The fragments at Alter do Chão are surrounded by natural (rather than planted) grassland, with many trees in the savannah matrix and the landscape has vast areas covered by forest, which may have helped to ameliorate the influences of forest fragmentation. © 2013 The Authors. more...

We studied the energy flow from C

Recently, a significant number of studies on neotropical forest bird communities have focused on factors influencing their richness, abundance, and habitat selection. However, few of them have considered populations or individual species, and how habitat structure affects their distribution and abundance. In this study, we investigated how the combined effects of some forest structure components affect the occurrence and abundance of a resident bird species, the scale-backed antbird Hylophylax poecilinotus (Cabanis, 1847). We tested the null hypothesis of no difference between the variation in forest structure components at locations where birds occurred and at locations where they did not. In a pristine Terra Firme forest at the Ducke Reserve, Manaus, we recorded bird occurrence and abundance using mist nets in 56 transects (1 km long each) within a 9 x 9 km trail grid covering 6400 ha. Also in the same 56 transects, we set 50 x 50 m plots and recorded the following seven components of forest structure and landscape: 1) canopy opening, 2) leaf litter, 3) tree abundance, 4) logs, 5) snags, 6) streams, and 7) elevation. We evaluated their effects on avian occurrence and abundance by using models of Multiple Logistic Regression (for bird occurrence) and Multiple Linear Regression (for bird abundance). The results suggested that H. poecilinotus occurred significantly more often in lowland areas, in areas located farther away from streams, and in areas bearing thicker leaf litter. Hylophylax poecilinotus was also more abundant in lowland areas and in areas located further away from streams. Overall, the results indicated that environmental heterogeneity produced by variation in forest structure components affects habitat use by this bird species in the Amazon forest.Uma quantidade significativa de estudos sobre comunidade de aves em florestas neotropicais tem recentemente se concentrado em fatores afetando a riqueza e abundância e seleção de habitat por elas. Entretanto, poucos têm considerado espécies individuais e como variações na estrutura do habitat afetam a distribuição das aves. Neste estudo nós analisamos como os efeitos combinados de alguns componentes de estrutura da floresta afetam a ocorrência e abundância de uma espécie de ave residente, o rendadinho Hylophylax poecilinotus (Cabanis, 1847). Nós testamos a hipótese nula de não diferença entre a variação nos componentes de estrutura da floresta nos locais de ocorrência das aves e locais onde elas não ocorreram na floresta. Para gerar informações da ocorrência e abundância do Rendadinho, nós usamos redes ornitológicas em 56 transectos de 1 km dentro de uma grade de trilhas cobrindo 6400 ha em floresta de terra firme na Reserva Ducke, Manaus. Foram utilizadas redes ornitológicas ao longo de 56 transectos, nos quais também foram colocadas parcelas de 50 x 50 m e registrados sete componentes de estrutura da floresta: 1) a abertura do dossel da floresta, 2) o folhiço, 3) a abundância de árvores, 4) os troncos mortos no chão e 5) os troncos mortos em pé, 6) a proximidade de igarapés e 7) a altitude. Os efeitos deles na ocorrência e abundância das aves foram avaliados usando-se modelos de regressão múltipla logística (para ocorrência das aves) e de regressão múltipla linear (para abundância de aves). Os resultados sugerem que H. poecilinotus ocorreu significativamente mais em áreas de baixio, em áreas de maior profundidade de folhiço, e em áreas distantes de igarapés. Hylophylax poecilinotus também foi mais abundante em áreas de baixio e em áreas distantes de igarapés. Os resultados indicam que a heterogeneidade ambiental produzida pela variação em componentes de estrutura da floresta afeta o uso do habitat por esta espécie de ave na floresta Amazônica. more...

We describe and analyze the bird community composition of the lacustrine water bodies of the seasonally flooded wetlands of the Mamiraua and Amana Reserves, Amazonas, Brazil. Bird surveys were conducted in 54 water bodies within four water body systems aboard a speedboat, in July 2003, at the peak of the high water season. We recorded 2,823 individuals representing 79 bird species associated with aquatic environments, mostly resident; of these, 34 were aquatic (exclusively associated with aquatic environments), and 19 were primarily piscivorous. The aquatic bird communities of Mamiraua and Amana comprise a few abundant species and a higher number of rare species. Seven species accounted for 71.7% of all 34 aquatic birds recorded. In general, the more elongated the water bodies, the lower the aquatic and piscivorous bird species richness, and the lower the bird abundance. Piscivorous bird abundance was not significantly related to water body shape. Matrices of bird species by water body were subje... more...

This study is the first to present a quantitative survey of bird species occurring in the archipelago of Anavilhanas, located in the Rio Negro in the Brazilian Amazon and is part of the Anavilhanas Ecological Station. We asked whether bird community composition is similar among the islands, and between islands and areas dominated by the surrounding upland terra firme forest on the left (east) margin of the Rio Negro. The surveys were conducted in November and December of 1988, using two complementary methods with mist nets and boat transects. A total of 232 bird species was found for Anavilhanas including a survey done in 1998. The families Tyrannidae and Thamnophilidae showed the highest number of species (16.4% and 9.0% of the total respectively). Some species not well known or having limited distributions are relatively frequently encountered in the archipelago, such as Spizastur melanoleucus, Mitu tomentosa, Phaethornis rupurumii, Xiphorhynchus kienerii, Thamnophilus nigrocinereus, Myrmotherula klagesi, Myrmoborus lugubris, Pipra filicauda, and Cephalopterus ornatus. Hybrid Multidimensional Scaling (HMDS) ordination analysis indicated that the bird community composition is similar among islands. However, the bird community composition on the islands was significantly different from that in sites of terra firme forest at Rio Negro margins. Anavilhanas is a unique ecological system in the Amazon and has it own avifauna. more...

Recent increases in Black Vulture (Coragyps atratus) and Turkey Vulture (Cathartes aura) numbers, particularly in urban-suburban settings, have led to more frequent human-vulture interactions, including vulture-aircraft strikes. This problem highlights the need for vulture management strategies, including determining habitat use by these species in urban settings. We investigated the effects of structures and landscape features on habitat use by Black and Turkey vultures in and around the city of Manaus in central Amazonian Brazil. We repeatedly surveyed 80 sites (3-9 visits per site in 2009-2010) and used detection histories to derive maximum-likelihood estimates of (1) vulture occurrence and detection probabilities and (2) environmental covariate effects on occupancy. Hierarchical logistic models showed that Black Vultures were associated with urban features such as open garbage containers and streams, but Turkey Vultures were associated with forest fragments. These results suggest that Black Vultures select environments where the food supply is abundant, whereas Turkey Vultures may avoid sites that attract Black Vultures in favor of forest remnants, a habitat for which they have specific foraging adaptations. Black Vulture management should focus on reducing the amount of food waste available to the birds in urban open garbage containers and streams, but Turkey Vulture management could be improved through removal of animal carcasses, and perhaps also removal of nests and roosts from forest remnants, especially near airfields. © 2014 Cooper Ornithological Society. more...

We studied the energy flow from C3 and C4 plants to higher trophic levels in a central Amazonian savanna by comparing the carbon stable-isotope ratios of potential food plants to the isotope ratios of species of different consumer groups. All C4 plants encountered in our study area were grasses and all C3 plants were bushes, shrubs or vines. Differences in δ13C ratios among bushes (x¯ = −30.8, SD = 1.2), vines (x¯ = −30.7, SD = 0.46) and trees (x¯ = −29.7, SD = 1.5) were small. However the mean δ13C ratio of dicotyledonous plants (x¯ = −30.4, SD = 1.3) was much more negative than that of the most common grasses (x¯ = −13.4, SD = 0.27). The insect primary consumers had δ13C ratios which ranged from a mean of −29.5 (SD = 0.47) for the grasshopper Tropidacris collaris to a mean of −14.7 (SD = 0.56) for a termite (Nasutitermes sp.), a range similar to that of the vegetation. However, the common insectivorous and omnivorous vertebrates had intermediate values for δ13C, indicating that carbon from different autotrophic sources mixes rapidly as it moves up the food chain. Despite this mixing, the frogs and lizards generally had higher values of δ13C (x¯ = −21.7, SD = 1.6; x¯ = −21.9, SD = 1.8, respectively) than the birds (x¯ = −24.8, SD = 1.8) and the only species of mammal resident in the savanna (x¯ = −25.4), indicating that they are generally more dependent on, or more able to utilise, food chains based on C4 grasses. more...

The amount of leaf litter fall produced by different tree species in tropical forests varies in space and time. Falling litter may cover seeds and thereby enhance their survival by making their detection by seed predators more difficult. Tests were made to determine whether Astrocaryum murumuru and Dipteryx micrantha seeds survive better in microsites covered by leaf litter. Seed numbers and litter cover on the forest floor were experimentally manipulated. How natural variation in leaf litter cover and thickness affects seed and seedling survival of these two plant species was also examined. Seed survivorship was significantly higher for both plant species in microsites with leaf litter than in those with bare soil. Results from an experiment in which the litter was not disturbed showed that Astrocaryum seed survival was positively correlated with litter thickness (defined as the number of overlying dead leaves). Astrocaryum seedling survival was also significantly affected by leaf litter; more seedlings survived in shallow litter. Leaf litter had no effect on Dipteryx seedling survival. The results of the study suggest that early recruitment of both Astrocaryum and Dipteryx is influenced by the spatial distribution and amount of forest leaf litter. more...

The role of regeneration strategies in structuring tropical tree communities has been a recent focus of attention of tropical ecologists. Canopy discontinuities created by tree-falls are considered to be critical to many rain forest trees for establishing and completing their life cycles. It was investigated whether it is advantageous for two common large-seeded and shadetolerant Amazonian tree species, the palmAstrocaryum murumuruand the legume,Dipteryx micrantha, to have their seeds dispersed to gaps. The dispersal process was simulated by placing experimental seeds and seedlings in gaps and in the shaded understorey, and then following their performance. Seeds and seedlings from the two species were used. The Cox proportional hazard model was used to estimate the survival functions and compare survivorship curves. Survival ofAstrocaryumseeds, and ofDipteryxseeds and seedlings, was higher in two gap zones (crown and bole) than in the shaded understorey (both near and far away from a conspecific adult). A higher proportion of seedlings of both plant species survived within gaps than in the shaded understorey over an 18-wk period. One year after the seedlings had been transplanted into gaps these patterns still held. Naturally occurringAstrocaryumseeds survived better beneath conspecific adult trees located within 30 m of gaps than beneath trees located 100 m from gaps. Variation in gap size was significant forDipteryxseeds, but not forDipteryxseedlings andAstrocaryumseeds and seedlings.Dipteryxseeds survived longer in smaller than in larger gaps. By colonizing tree-fall gaps, these two species improved their chances of completing their life cycles. more...

The foraging mode and vertical distribution of tyrant flycatchers of twelve sympatric species (Tyrannidae) were compared between forest edge and savanna in the Brazilian Amazon. Five species can be regarded as aerial salliers or hawkers, four as gleaners, and three as generalist hunters. Their patterns of foraging behavior were significantly different among the species but not in the two habitats. Perch positions changed significantly according to the time of day. Generally the tallest trees in a given plot were chosen, with the larger bird species perching more often at the top of the trees. Factors that affect the structure and behavior of this flycatcher guild are discussed. more...

For the first time, and in a large spatial scale, the influence of ecological properties on the aquatic bird community of black water lakes in Brazilian Amazonia is evaluated. Bird surveys were conducted in 45 lakes. A total of 3626 individuals in 48 bird species were recorded; of these, 31 are aquatic, and 18 of these are primarily piscivorous. Bird richness and abundance were not significantly related to lake shape and productivity but were influenced by hydrological period (low versus high), water depth, transparency, lake isolation, and habitat richness. Matrices of bird species by lake were subjected to multivariate analyses (NMDS) to evaluate how these parameters influence bird community. The variation in bird species composition was positively correlated to lake depth and isolation and negatively correlated to water transparency and habitat richness. The results indicate that period, lake physical characteristics (depth, water transparency), isolation, and habitat richness are determinants of aquatic bird community composition in the black water lake systems of Amazonia. © Copyright 2012 Renato Cintra. more...

The study was conducted at the Adolpho Ducke Forest Reserve. The occurrence and abundance of the adult palms Attalea attaleoides (Barb. Rodr.) W Boer, A. microcarpa Mart., Euterpe precatoria Mart., Geonoma aspidiifolia Spruce, Iriartella setigera (Mart.) H. Wendl, Oenocarpus bacaba Mart., O. bataua Mart., O. minor Mart., Socratea exorrhiza (Mart.) H. Wendl were observed in 40 50 x 50 m plots and the seedlings in two 50 x 2 m plots located inside the 40 plots demarcated to register the adults. The topographical gradient was divided into swamp valley, slope and plateau based on the altitudes and characteristics of these environments. Occurrence and abundance data were used as dependent variables in the models of Analysis of Variance to verify differences in the topographical gradient. Changes in species composition were evaluated using multivariate analysis of ordination. The distribution and abundance of the seedling and adult phases varied with the topographical gradient. The variation in species composition in different topographic levels probably occurs due to the different responses of the species to the variation in forest heterogeneity, produced by the spatial variation of the structural components of the forest. Key words: palms, Central Amazon, topography, distribution, “Terra Firme” forest. more...

We investigated how forest structure affects the occurrence and abundance of three owl species: the crested owl Lophostrix cristata Daudin, 1800, the Amazon pygmy owl Glaucidium hardyi Vielliard, 1990, and the tawny-bellied screech owl Megascops watsonii Cassin, 1849. We surveyed the owls mostly between 07:00 and 11:00 pm from July 2001 to April 2002, in eighteen 8 km transects along trails at the Ducke Reserve, Manaus, Central Amazon, Brazil. We staked out 50 × 50 m plots where the presence and absence of the owls were recorded. We compared some compo-nents of the forest structure between plots where owls were present and plots where they were absent. The spatial variation in these components were related to the occurrence and abundance of the owls using models of multiple logistic and multiple linear regressions analysis, respectively. Lophostrix cristata is rare in many other areas of the Amazon forest, but it was the most abundant in our study area. Lophostrix cristata and G. hardyi were more concentrated along the uplands (central plateau), which divide the reserve into two drainage water-basins. Megascops watsonii was distrib-uted mainly in the southeastern part of the reserve. Glaucidium hardyi was more often found in areas with larger canopy openness. In areas with higher abundance of snags, there was significantly higher occurrence of L. cristata and M. watsonii. Megascops watsonii was also more abundant in areas with higher abundance of forest trees and in areas bearing shallower leaf litter on the forest floor. This study is the first to analyze at large spatial scale the effects of forest structure on neotropical forest top predator nocturnal birds. The results indicate that forest structure can affect the occurrence and abundance of owls in the Amazon forest. more...

The effects of fire on the composition of a bird community were investigated in an Amazonian savanna near Alter-do-Chão, Pará (Brazil). Mist-net captures and visual counts were used to assess species richness and bird abundance pre- and post-fire in an approximately 20 ha area. Visual counts along transects were used to survey birds in an approximately 2000 ha area in a nearby area. Results using the same method of ordination analysis (multidimensional scaling) showed significant effects of fire in the 20 ha and 2000 ha areas and strongly suggest direct effects on bird community composition. However, the effects were different at different spatial scales and/or in different years, indicating that the effects of fire vary spatially and/or temporally. Bird community composition pre-fire was significantly different from that found post-fire. Using multiple regression analysis it was found that the numbers of burned and unburned trees were not significantly related to either bird species richness or bird abundance. Two months after the fire, neither bird species richness nor bird abundance was significantly related to the number of flowering trees (Lafoensia pacari) or fruiting trees (Byrsonima crassifolia). Since fire is an annual event in Alter-do-Chão and is becoming frequent in the entire Amazon, bird community composition in affected areas could be constantly changing in time and space. Os efeitos do fogo na composição da comunidade de aves foram estudados em uma savanna perto de Alter-do-Chão, Pará, Brasil. Capturas usando redes ornitológicas e contagens visuais foram usadas para amostrar a riqueza de espécies e abundância de aves antes e depois do fogo em uma área de aproximadamente 20 ha. Contagens visuais ao longo de transectos foram usadas para amostrar aves numa área vizinha de aproximadamente 2000 ha. Resultados usando os mesmos métodos de análise de ordenação (escalonamento multidimensional) mostraram efeitos significativos do fogo nas áreas de 20 ha e 2000 ha, e sugerem fortemente que houve efeitos diretos do fogo na composição da comunidade de aves. Entretanto, os efeitos foram diferentes nas diferentes escalas espacias e ou anos, indicando que os efeitos do fogo variam espacialmente e ou temporalmente. A composição da comunidade de aves antes do fogo foi significativamente diferente daquela depois do fogo. Análise de regressão múltipla indica que o número de árvores queimadas e não queimadas não foi significativamente relacionado à riqueza de espécies ou à abundância de aves. Dois meses depois do fogo, nem a riqueza de espécies nem a abundância de aves foram significativamente relacionadas ao número de árvores florindo (Lafoensia pacari) e árvores frutificando (Byrsonima crassifolia). Como o fogo é um evento anual em Alter-do-Chão, e está se tornando frequente na Amazônia, as comunidades de aves em áreas afetadas pelo fogo podem estar mudando constantemente no tempo e no espaço. more...

The mechanisms that maintain tree diversity in tropical rain forests are still in debate. Variations in forest structural components produce forest microenvironmental heterogeneity, which in turn may affect plant performance and have been scarcely analyzed in the Amazon. Palms are widespread in the Neotropical rainforests and have relatively well known taxonomy, apart from being ecologically and economically important. The understanding of how palms respond to variation in the forest structural components may help to explain their abundance and richness in a given area. In this study, we describe a palm community and analyze how it is affected by forest microenvironmental heterogeneity. In a pristine "Terra Firme" forest at Reserva Ducke, Manaus, we recorded all adult palm trees in twenty 100 × 10 m plots. In the same plots we recorded the variation in canopy openness, the leaflitter thickness and counted all non-palm forest trees. A total of 713 individuals in 29 palm species were found. The three most abundant species were Astrocaryum sciophilum (Miq.) Pulle, A. gynacanthum Mart. and Attalea attaleoides (Barb. Rodr.) Wess. Boer. The most locally abundant species were also very frequent or occurred in a larger number of plots. There were no significant effects of litter depth, forest canopy openness and forest tree abundance on palm richness. However, in areas where leaf litter was thicker a significant lower number of palm trees occurred. In microsites where proportionally more incident light was reaching the forest understory, due to higher canopy opening, significantly more palm trees were present. Os mecanismos que mantêm a diversidade de plantas em florestas tropicais estão ainda em debate. Variações nos componentes estruturais da floresta produzem heterogeneidade microambiental na floresta, que por sua vez devem afetar as plantas, e raramente têm sido analisados na Amazônia. As palmeiras são amplamente distribuídas em florestas neotropicais e tem a sua taxonomia bem conhecida, além de sua importância ecológica e econômica. O entendimento de como as palmeiras respondem às variações nos componentes estruturais da floresta pode ajudar a explicar a abundância e a riqueza delas em uma dada área. Neste estudo descrevemos uma comunidade de palmeiras e analisamos como ela é afetada pela microheterogeneidade ambiental da floresta. Em uma floresta de terra firme na Reserva Ducke, Manaus, registramos todas as palmeiras adultas em 20 parcelas de 100 × 10 m. Nas parcelas também registramos a variação na abertura do dossel, a profundidade de folhiço e o número de árvores da floresta. Setecentos e treze indivíduos de 29 espécies de palmeiras foram registrados. As três espécies mais abundantes foram Astrocaryum sciophilum (Miq.) Pulle, A. gynacanthum Mart. and Attalea attaleoides (Barb. Rodr.) Wess. Boer. As palmeiras mais abundantes localmente também foram muito frequentes e ocorreram na maioria das parcelas. Não houve efeito significativo da profundidade de folhiço, abertura do dossel da floresta e abundância de árvores, na riqueza de espécies de palmeiras. Em microsítios com maior profundidade de folhiço ocorreu significativamente menor abundância de palmeiras. Quanto maior a abertura do dossel da floresta, um número significativamente maior de palmeiras estava presente. more...

In forest of the Brasilian Amazon, the Black-eared Fairy (Heliothryx aurita) uses a gliding fall, similar to that movement presented by the fall of a dead leaf, when leaving the nest. This behaviour may protect adult or nest against forest hawk predators. more...

Foraging parameters of two ant species, Pseudomyrmex triplarinus and Crematogaster sp., on P. triplarinus-occupied shrubs of Triplaris surinamensis were evaluated in a semi-deciduous forest of Mato Grosso, western Brazil. Live workers of the termite Microcerotermes strunckii, used as baits for ants, were placed on leaves in the lower, medium and upper thirds of the crown of thirty experimental Triplaris (nine baits/plant). Besides attacking more than twice as many baits as Crematogaster (131 against 59), Pseudomyrmex also attacked them signifi cantly faster. Pseudomyrmex patrolled the plant uniformly, while Crematogaster patrolled more intensively the lower portion of the crown of Triplaris. Baits retrieved by Pseudomyrmex were taken to their nests in the stem galleries of Triplaris; those retrieved by Crematogaster were carried to nearby nests in the forest understory. Greater aggressiveness and alertness to foreign objects (i.e. baits), better eyesight, larger size, and an individual foraging technique appear to be responsible for the greater foraging success of Pseudomyrmex when compared with Crematogaster. more...

Analysis of a three-year bird survey in the pantanal of Poconé revealed that most of the resident and seasonal birds are habitat generalists, using two or more habitats. In this study, previously sampled habitats were ranked in relation to species richness and stability (as measured by the ratio of seasonal to resident species). In all, nine habitats were grouped into three categories; results are as follows: 1) forests: more species-rich and more stable; 2) cerrado: intermediate levels; and 3) aquatic: less species-rich and less stable. The number of seasonal species remained relatively constant in forests throughout the year, while increasing in the other habitats during the dry season. The abundance of resident species seems to be related to species use of multiple habitats. Although many species were found to be habitat generalists, we discuss possible consequences of habitat loss and other human impacts on efforts to conserve this important bird community. Análises de um levantamento de três anos da avifauna do Pantanal de Poconé indicam que a maioria das espécies residentes e estacionais utiliza dois ou mais tipos de habitats. Estes habitats podem ser ordenados num gradiente de riqueza de espécies e estabilidade (medida pela proporção de espécies estacionais): 1) matas - mais ricas e estáveis; 2) cerrados e pastos - intermediários; e 3) campos inundáveis/aquáticos - menos ricos e menos estáveis. Enquanto a proporção de espécies estacionais nas matas permanece relativamente constante ao longo do ano, há aumento significativo destas espécies nos outros habitats durante a estação seca. A abundância das espécies residentes parece ligada ao uso de maior variedade de habitats. São discutidas possíveis implicações decorrentes da destruição de habitats e perturbações antrópicas na conservação desta comunidade de aves. more...

We present a synthesis of the first 10 years of Long Term Ecological Research project in Amazonian Forest. We elucidate the natural dynamics of forest ecosystem processes and associated biota, and its changes caused by distinct pressures of selective timber extraction and forest fragmentation. We found that, for both plants and animals, densities of individuals and distribution of species assemblages are spatially heterogeneous at the mesoscale, even in relatively undisturbed forests, and that associations with topo-edaphic variables allow prediction of a considerable part of this variation. For biological groups whose dynamics were studied in the short-term, levels of change in species composition and densities were relatively high, and these changes were generally in tune with spatial environmental variation. The impact of selective logging on assemblages and ecosystem processes was normally moderate, and around 19 years were needed for recovering forest biomass and tree size distribution. Continued studies are needed to determine the time required for recuperation of timber stocks and pre-logging floristic composition. Selective logging appears to be compatible with the biodiversity conservation, but reduction and better planning of road access may be more important than planned logging intensities. Habitat-loss' impact on organisms and ecosystem processes is large and long-lasting, since it induces the loss of many taxonomic groups and species, higher tree mortality and accelerated forest dynamics. There was a negative synergy between the impacts of habitat loss and climatic changes, and a better understanding of these processes can only be obtained through long-term research. © 2015 Associação Brasileira de Ciência Ecológica e Conservação. more...

Only one published study (Crawshaw and Schaller, 1980) has discussed the nesting biology of Caiman yacare. Most nests described in that study were found along the Bento Gomes River, on the border of the Pantanal, a large (100,000 km2) area of seasonal swampland of the upper basin of the Paraguay River. Because Crawshaw and Schaller obtained data on only 14 nests, within the Pantanal proper, I continued research in the 1984 and 1985 breeding seasons in the same geographical area, at approximately 56?59'W, 17?16'S in the Santa Isabel, Rio Alegre, and Jofre ranches. more...

Examen du comportement maternel d'une femelle adulte C. yacare entouree de 22 jeunes, durant 6 mois, apres leur naissance

Informações ecológicas sobre a ocorrência e abundância das espécies são cruciais para avaliar a influência de fatores ambientais sobre populações, para reconhecer mudanças no tamanho das populações e para reconhecer locais importantes para a manutenção de populações viáveis. Reconhecer relações entre as populações e características ambientais pode ser útil para gerar predições sobre efeitos de eventos futuros. Estimamos a distribuição, a influência das características de praias para reprodução na ocupação e a abundância, considerando probabilidades de detecção de trinta-réis-anãos (Sternula superciliaris), gaivotas (Phaetusa simplex) e corta-águas (Rynchops niger) no Arquipélago de Anavilhanas, Amazonas, Brasil, durante as estações reprodutivas 2008 e 2009. Em 2008 e 2009 registramos a presença ou ausência de indivíduos nidificando em visitas repetidas a cada praia disponível no arquipélago para estimativas de ocupação. Em 2009 utilizamos o método de dois observadores em pontos de contagem para estimar a abundância das aves no arquipélago considerando possíveis diferenças de detecção entre observadores. Localizamos 26 praias disponíveis em 2008 e 30 em 2009. Uma praia abrigou ≥ 28% do total de trinta-réis-anão contados e dois locais concentraram ≥ 65% das gaivotas contadas durante as temporadas de reprodução de 2008 e 2009. A probabilidade de detecção, p (SE) em 2008 e 2009, do trinta-réis-anão foi 0,8272 (0,0534) e 0,8737 (0,0341), da gaivota foi 0,8668 (0,0512) e 0,7323 (0,0577), do corta-água foi 0,8321 (0,0551) e 0,9429 (0,0392). A ocupação no arquipélago, psi (SE) em 2008 e 2009, do trinta-réis-anão foi 0,5841 (0,0982) e 0,6334 (0,0880), da gaivota foi 0,5025 (0,0986) e 0,4006 (0,0896), do corta-água foi 0,5432 (0,0987) e 0,2333 (0,0772). Trinta-réis-anões, gaivotas e corta-águas preferiram nidificar em praias maiores, ilhas com pouca ou sem vegetação, praias com maior exposição a água circundante, locais mais distantes da terra firme e/ou de ilhas e locais mais próximos às maiores colônias. O número total de indivíduos contados em 2008 foi 133 trinta-réis-anões, 72 gaivotas e 103 corta-águas e as estimativas de abundância em 2009 (N ± SE) foram 192,36( ± 1,24) trinta-réis-anões, 79,56 (± 0,77) gaivotas e 31,22( ± 0,48) corta-águas. A probabilidade de detecção geral, ou seja, de uma ave ser contada quando dois observadores presentes foi alta para as três espécies (p ≥ 0,992), mas foi diferente entre espécies e foi menor para cada observador. Nossos resultados sugerem que o uso de locais para reprodução de trinta-réis e corta-águas nestes dois anos foi influenciado por uma combinação entre características do local e atração intra-específicas entre as aves. Sugerimos, com base em nossos resultados, o uso do método de dois observadores para pontos de contagem para estimativas mais acuradas de abundância, avaliações de mudanças no tamanho de populações e medidas de conservação para aves associadas a ambientes aquáticos. Palavras-chave: arquipélago fluvial; aves coloniais; características da praia; dois observadores; Lari-dae; probabilidade de detecção; trinta-réis-grande; talha-mar Ecological information on species occurrence and abundance are crucial to assess the influence of environmental factors on the populations, to recognize changes in population sizes and to identify key sites to maintain viable populations. We estimated the distribution, influence of site features on colony site occupancy and abundance estimates accounting for detection probabilities of Yellow-billed Terns(Sternula superciliaris), Large-billed Terns (Phaetusa simplex) and Black Skimmers (Rynchops niger) breeding in the Anavilhanas Archipelago, Amazonas, Brazil. We did repeated surveys on beaches available in 2008 and 2009 breeding seasons and conducted point counts with a double observer approach in 2009. We mapped 26 potential sites in 2008 and 30 in 2009, one site hosted ≥ 28% of total Yellow-billed Terns counted and two sites hosted ≥ 65% of Large-billed Terns counted. Detection probability, p (±SE) in 2008 and 2009, for Yellow-billed Tern was 0.8272 (±0.0534) and 0.8737 (±0.0341), for Large-billed Tern was 0.8668 (±0.0512) and 0.7323 (±0.0577), for Black Skimmer was 0.8321 (±0.0551) and 0.9429 (±0.0392). Site occupancy, psi (SE) in 2008 and 2009, for Yellow-billed Tern was 0.5841 (±0.0982) and 0.6334 (±0.0880), for Large-billed Tern was 0.5025 (±0.0986) and 0.4006 (±0.0896), for Black Skimmer was 0.5432 (±0.0987) and 0.2333 (±0.0772). Terns and Black Skimmers preferred to nest in larger beaches, islands with small percent of or no vegetation cover, beaches more exposed to open water, sites further away from river margin, more isolated from island, and closer to main colonies. A total of 133 Yellow-billed Terns, 72 Large-billed Terns and 103 Black Skimmers were counted in 2008 and in 2009 abundance estimates (N ± SE) were for Yellow-billed Tern = 192.36 (± 1.24), for Large-billed Tern = 79.56 (± 0.77) and for Black Skimmer = 31.22 (± 0.48). Overall detection probability-p (probability of a bird being detected when two observers counting) was high for the three species (p ≥ 0.992), but it was different between species and between observers and was lower for each observer separate. Our results suggest that breeding site use by terns and Black Skimmer may be influenced by a combination among habitat features and intraspecific attraction of these birds. Based in our estimates of detection probabilities we suggest the use of the double observer approach for point counts for more accurate abundance estimates, population changes assessment and conservation planning for waterbirds. more...

Assembléias de aves aquáticas e piscívoras foram estudadas durante quatro anos no Pantanal Matogrossense. Foram realizados censos populacionais em transectos lineares em 1999 e 2000 ao longo da Estrada Parque Transpantaneira em Poconé-MT, e em 2002 e 2003 foram realizados censos das aves em 20 lagos ao longo da mesma rodovia. Foram determinadas a composição de espécies e a variação da abundância ao longo do ano e em anos subseqüentes. Foi verificado o papel de fatores abióticos (pluviosidade, temperatura do ar, insolação, tamanho e profundidade do lago, temperatura, transparência e pH da água) e bióticos (cobertura e riqueza de espécies de macrófitas aquáticas, e biomassa e riqueza de espécies de peixes) em prever a variação na riqueza e abundância e na composição de espécies de aves aquáticas e piscivoras no Pantanal. Waterfowl and fish-eating assemblies were studied for four years in Pantanal . Population censuses were conducted in line transects in 1999 and 2000 along the Transpantaneira Park Road in Poconé -MT , and 2002 and 2003 census birds were performed in 20 therealong lakes highway. They determined the species composition and abundance variation of the throughout the year and in subsequent years. It was found the role of abiotic factors ( rainfall , air temperature , heat stroke , size and depth of the lake, temperature , transparency and water pH ) and biotic ( cover and species richness aquatic weeds , and biomass and richness of fish species ) to predict the variation wealth and abundance and species composition of aquatic birds and piscivorous the Pantanal. more...