Abstract in English:The coordinated feeding tactics used by delphinids are influenced by differences in the distribution of prey species, season, and opportunities for social learning. In the present study, we compared the coordinated feeding behavior of two populations of the Guiana dolphin, Sotalia guianensis, in southeastern Brazil, and how these feeding tactics vary seasonality and in the presence of calves. We observed eight types of coordinated feeding tactics, which differed in frequency and in the mean number of individuals engaged in them, and between both areas. Feeding tactics used to herd and capture prey were the most frequent and engaged a greater number of individuals, suggesting that these tactics are better for capturing fish that gather in larger schools. Furthermore, the seasons influenced the occurrence of different prey items, which in turn modified the feeding tactics of the dolphins. In the Ilha Grande Bay we observed that bouts lasted longer and larger groups engaged in the feeding tactics, which may be associated with the seasonal spawning of larger schooling fish such as Sardinella brasiliensis (Steindachner, 1879) (Teleostei: Clupeidae). However, in the Sepetiba Bay, we observed longer feeding bouts and a smaller number of individuals engaged in the feeding tactics during autumn-winter. This may be associated with the fact that the most abundant prey species, Micropogonias furnieri (Desmarest, 1823) (Teleostei: Sciaenidae), gathers in small schools. Calves were present in 95% of all coordinated feeding tactics that occurred in the Ilha Grande Bay and in approximately 61% of feeding tactics in the Sepetiba Bay, suggesting that these areas are important for social learning. This study provides more information about feeding tactics and improves knowledge of the coordinated behavior of Sotalia guianensis (Van Benéden, 1864).
Abstract in English:Petrolisthes armatus (Gibbes, 1850) is a porcellanid crab with a wide geographical distribution. In the present study we analyzed variations in the abundance of P. armatus adults and larvae over an annual cycle in the Marapanim estuary of the Amazon coastal zone, in the northeastern portion of the state of Pará, Brazil. Particularly, we focused on the presence of ovigerous females and timing of larval release, with the aim of elucidating reproductive patterns in a tropical estuarine system. The mean density of P. armatus larvae (zoea I and II) correlated positively with the salinity of the shallow waters of the estuary, whereas the abundance of adults correlated with the salinity registered in water samples collected from the benthic environment. There was also a significant positive correlation between larval density (zoea I and II) and water temperature. Ovigerous females were captured throughout the study period, from August 2006 to July 2007, but were more abundant in June and less abundant during the rainy months, between February and May. Larvae were only present during the dry season and transition months (June to January), and were absent during the rainy season (February to May). Petrolisthes armatus reproduces throughout the year in the Marapanim estuary and all developmental stages of this species (zoeal stages I and II, megalopae and adults) are found in the estuary. The results indicate that the study area is an important environment for the reproduction of this decapod.
Abstract in English:Formicivora littoralis (Gonzaga and Pacheco, 1990), the Restinga Antwren, considered the only endemic bird species of the Restinga ecosystem (sandy plain coastal vegetation), is threatened with extinction. The scientific literature provides little information on the biology of this bird, which was discovered in 1990. We evaluate gender-related differences in the composition of the diet and morphometric measurements of this species. We tested the hypothesis that the sexes differ in what they eat and in morphometric characters. Our results revealed that the diet of the Restinga Antwren includes mainly arthropods, which is consistent with the diets of other Thamnophilidae. The lack of differences in the composition of the diet between the sexes does not support the hypothesis that habitat partitioning to avoid intraspecific competition is taking place. We found significant differences in six morphometric measurements, two in the beak and four in body size. It is possible that intraspecific differences between the sexes are a result of sexual selection, a hypothesis that needs to be tested.
Abstract in English:Increasing populations of the Black Vulture, Coragyps atratus (Bechstein, 1793) and the capacity this bird has to live near humans has resulted in vulture-human conflicts. These conflicts increase the need for the effective management of vultures. Improved understanding of communal roosting dynamics is a key aspect of vulture biology that provides information for effective management that can mitigate conflicts. Here we investigated factors influencing roosting site selection by Black Vultures in Manaus. We monitored 40 native vegetation remnants (VR), visiting each VR twice (two independent observers) between 5:00 p.m. and 6:00 p.m. once every two-three months from June to November 2011. Using maximum-likelihood analysis and information-theoretic multimodel inference, we investigated the effects of VR covariates (size, shape, and location relative to feeding sites, to thermal power plants, and to other VRs) on VR occupancy by roosting Black Vultures. Distance to feeding sites (mainly garbage-dumping sites) was identified as the most important covariate (model-averaged β = -0.62, SE = 0.26) and the other variables had no significant effects. Our results indicate that Black Vultures adjusted to the nearest possible roost to the food source to reduce the cost of movement. This suggests that reducing Black Vulture access to food through simple waste management and sanitation policies, including public education, may help reduce vulture-human conflicts in Manaus.
Abstract in English:The adverse effect that insecticides have on spider populations is of major concern since these predators are a component in the biological control of rice insect pest populations. This study was designed to determine the effect of the pyrethroid insecticide, Lambda-cyhalothrin, on spider populations in rice fields. Treatments consisted of plots treated once with the insecticide and untreated plots (control). Spiders were sampled four times per crop year over a two year period in each of three sites in the state of Rio Grande dol Sul, Brazil. Treatments were replicated four times. Sweep net sampling was conducted to sample the araneofauna. Overall 1,961 spiders were collected, with a predominance of juveniles over adults. Between treatments, there were significantly larger numbers of spiders and species richness in areas without insecticide. There were also significant differences among areas (sites) and among days after the insecticide application. Of the 12 recorded families, Araneidae and Tetragnathidae dominated, and were both strongly affected by insecticide application, decreasing more than 50% in those locations. Overall, 37 species were recorded (insecticide: 29; without: 26), eleven species were exclusive for rice without insecticide and eight for rice with insecticide. Alpaida veniliae (Keyserling, 1865) (n = 236) and Tetragnathaaff.jaculator (108) were the most abundant in both treatments, but with large decreases in abundance in rice with insecticide. Among guilds, the predominance was for orb weavers (67.3%) in all locations, but with much lower values for those spiders in rice with insecticide application. This study illustrates that the spider fauna in rice fields are adversely affected by the application of the insecticide Lambda-cyhalothrin.
Abstract in English:The goal of this study was to assess the population structure of Pseudis bolbodactyla Lutz, 1925 using natural markings to identify individuals. Recruitment, survival, and population size estimations were obtained using the Jolly-Seber stochastic method. A total of 166 individuals were captured, and the striped, spotted, and dotted patterns that make their recognition possible were recorded. Of the specimens captured, 27 were recaptured, including some at pre and post-metamorphic stages. The estimate maximum population size was 52. The indices of survival and recruitment varied among samplings. Sexual dimorphism in size and in the operational sex ratio were detected. Despite the limited scope of our characterization of the P. bolbodactyla population, our data might be useful in the interpretation and elaboration of new hypotheses about ecological processes acting on anuran populations.
Abstract in English:Balancing power production and environmental conservation can be problematic. The objective of this study was to investigate the abundance of marsh deer in the Paraná River Basin, above the Sergio Motta (Porto Primavera) Dam, before and after the impact of the dam closure. A fixed-wing, flat window aircraft was used to survey study transects. Observations were recorded based on the distance sampling line transect method, assuming that the detection probability decreases with increased distance. The abundance of marsh deer in the survey region prior to flooding was estimated to be 974 individuals (CV = 0.23). The overall abundance dropped from 974 to 444 (CV = 0.26) individuals after flooding, an overall reduction of 54%. This reduction can be attributed to the direct impact of the flooding process, but it was likely exacerbated by indirect effects, such as increased disease, hunting, and reduction in food availability. Prior to flooding, the marsh deer was distributed widely throughout the dam's catchment area; however, the marsh deer habitat was almost completely destroyed by the flooding process. This situation highlights the need to implement management strategies that ensure the survival of the remaining fragmented population.
Abstract in English:The richness and abundance of Collembola species can be influenced by many biotic and abiotic factors, mainly humidity. The semiarid region of Brazil is dominated by Caatinga dryland vegetation which experiences distinct seasonal alterations of its physiognomy linked to regional rainfall regimes. The present study evaluated the environmental factors affecting populations of Collembola in an area of Caatinga vegetation in Northeastern Brazil during a 12-months period. Specimens were collected by active searching in ten 20 x 20 m plots, with a sampling effort of 1 hour/person/plot. A total of 1231 specimens were collected, comprising 15 morphospecies, 12 genera, and nine families. Both species richness and individual abundances demonstrated oscillations during the year, with the highest values occurring during the rainy season; rainfall was the principal predictive variable for the observed temporal oscillations. Minimum temperatures and precipitation influenced the structural composition of the Collembola. Populations of Collembola demonstrated clustered distribution during the year. The direct and indirect effects of precipitation on the quality of microhabitats and resource availability were apparently responsible for the numerical and compositional alterations of the Collembola fauna observed in the Caatinga site.
Abstract in English:In this contribution we studied the trophic ecology of four Characidae species from the Cavalo Stream, upper Tocantins River, considering diet overlap and trophic niche breadth. The diet of the four species was composed of adult and immature insects, both autochthonous and allochthonous in origin. Autochthonous items dominated the diet of Moenkhausia dichroura (Kner, 1858), Bryconamericus sp., and Creagrutus atrisignum Myers, 1917. By contrast, allochthonous items were dominant in the diet of Astyanax bimaculatus (Linnaeus, 1758). Trophic niche breadth varied among species, with the highest value recorded for M. dichroura (0.48), followed by Bryconamericus sp. (0.39), A. bimaculatus (0.33) and C. atrisignum (0.29). Similarity analysis revealed two groups with different patterns of food preference. The first group was composed of insectivorous and the second by omnivorous species. The overlap in food items consumed by the four species studied was high. We suggest that resources are not limited in this stream and that competition might not be regulating these populations. This is one more case corroborating the general pattern registered for Tropical environments, where resource partitioning and specialization are responsible by the organization of fish communities.
Abstract in English:This study investigates the shrimp found in non-vegetated areas of an estuary of the Amazon River. We ascertained the input of juveniles, species' biometrics and the influence of environmental factors on the abundance of species. The samples were collected monthly, from August 2006 to July 2007, in two places in the estuary, each next to an island. For collecting, we used a manual trawl to perform three hauls per month, totaling 36 samples per site. The abundance of shrimps was estimated as a function of the density of specimens per unit area. We used the Spearman's correlation to test the hypothesis that there is significant correlation between the average of the environmental variables measured and variations in shrimp density. The Kruskal-Wallis and the Mann-Whitney tests showed that there were significant differences in environment factors (temperature and salinity) among the months and sites. We obtained 6,091 shrimps, from which 5,231 (85.88%) were caught off the Arapiranga Island and 860 (14.12%) off the Mosqueiro Island, Palaemonidae and Penaeidae were the only families recorded. Five species were collected: Macrobrachium amazonicum (Heller, 1862), Macrobrachium surinamicum Holthuis, 1948, Macrobrachium carcinus (Linnaeus, 1758), Macrobrachium rosenbergii (De Man, 1879), and Farfantepenaeus subtilis (Pérez-Farfante, 1967). The latter (pink shrimp) was found for the first time in oligohaline environments (0-8). Macrobrachium amazonicum was the most abundant species. The recruitment of M. amazonicum juveniles was continuous throughout the year. The population of M. surinamicum was composed by juveniles and adults and that of F. subtilis exclusively by juveniles. The environmental factors analyzed were variable throughout the year and seem to explain the patterns of shrimp species occurrence in the region, the variation in their abundance and juvenile recruitment.
Abstract in English:Atlanteuptychia Freitas, Barbosa & Mielke, gen. nov. is proposed for Euptychia ernestina Weymer, 1911 and illustrated. This taxon lacks the posterior projection of the tegumen, a synapomorphy of Euptychia Hübner, 1818, and does not share morphological synapomorphies with Cyllopsis R. Felder, 1869 and Paramacera Butler, 1868, two Central American genera apparently closely related to Euptychia ernestina, based on molecular data. This evidence supports the proposition of a new genus endemic to the Atlantic Forest, A. ernestina stat. nov.
Abstract in English:The Neotropical sharpshooter Parasubrasaca felixi, gen. nov., sp. nov., is described and illustrated from the Atlantic Rainforest of Southeastern Brazil (state of Espírito Santo). The new genus can be distinguished from other members of the Cicadellini by several morphological features, including a unique modification of the basal portion of the aedeagus, which bears a conspicuous, ventrally directed projection that articulates with the connective. The projection bears a pair of strong spines directed posteriorly. In addition to the external morphology, color pattern, and male genitalia, the female genitalia of the new taxon are also described in detail. A discussion comparing the new genus with similar Neotropical taxa (Subrasaca Young, 1977, Soosiulus Young, 1977, Ramosulus Young, 1977, Geitogonalia Young, 1977, Ladoffa Young, 1977, and Scopogonalia Young, 1977) is provided.
Abstract in English:Megalobulimus K. Miller, 1878 is a genus of land snails that includes the largest living snails in the Neotropics. The main goal of this paper was to review all species of Megalobulimus that have a red lip, and which are distributed in Peru. We carried out a detailed description of their shells and soft parts, and conducted a multivariate analysis on their shells and geographic distribution. There are two species reported from Peru, Megalobulimus capillaceus (Pfeiffer, 1855) and Megalobulimus separabilis (Fulton, 1903). Megalobulimus capillaceus is known to occur in three regions - San Martín, Huánuco and Cusco - but the Cusco population is undoubtedly different from all remaining populations, and is recognized herein as a new species, Megalobulimus florezi sp. nov. This species has a more elongated shell, penis club-shaped, epiphallus longer, and free oviduct longer than M. capillaceus. By contrast, the male genitalia of M. separabilis is filiform and does not present an external diverticulum in the free oviduct.
Abstract in English:Notonecta itatiaia sp. nov. is described from the state of Rio de Janeiro. Like other Notonecta species that occurs in Brazil, N. itatiaia has no remarkable diagnostic features than the shape of genital capsule. Along with the first description of a Notonecta from Brazil in eighty years, N. disturbata is newly recorded from the states of Pará, Piauí and São Paulo, and N. pulchra from Pará. A key to species of Notonecta (males) occurring in Brazil is given.
Abstract in English:The Neotropical palm swift, Tachornis squamata Cassin, 1853 (Apodidae), inhabits palm forests in the northern, northeastern and central regions of South America. At the Chapada do Apodi, Brazilian Caatinga, we investigated how the Neotropical palm swifts use palm trees to roost in two areas: urban and exurban. From May to November 2011 and from March to June 2012, out of the breeding season of the species, we compared the differences between the descriptive parameters of the palm-roosts and the activity levels of the swifts in urban and exurban roosting. We sampled 30 carnauba palm-roosts in exurban areas and 32 carnauba palm-roosts and 26 Chinese fan palm-roosts in urban areas for a period of 132 days, a total of 528 hours of sampling. The number of wasp nests was greater in carnauba palm-roosts in exurban areas than in palm-roosts in urban areas. However, there were greater numbers of swift nests and swifts in palm-roosts in urban areas than in exurban areas. Moreover, the activity levels (number of entry and exit events of swifts in the palm-roost) during sunrise (05:00-05:20 a.m.) and sunset (05:41-06:00 p.m.) were significantly lower in the exurban area than in the urban area. These results may contribute to establish better management practices for the coexistence between wildlife and humans in cities.