Body size predicts ontogenetic nitrogen stable-isotope (δ15N) variation, but has little relationship with trophic level in ectotherm vertebrate predators.

Large predators have disproportionate effects on their underlying food webs. Thus, appropriately assigning trophic positions has important conservation implications both for the predators themselves and for their prey. Large-bodied predators are often referred to as apex predators, implying that they are many trophic levels above primary producers. However, theoretical considerations predict both higher and lower trophic position with increasing body size. Nitrogen stable isotope values (δ15N) are increasingly replacing stomach contents or behavioral observations to assess trophic position and it is often assumed that ontogenetic dietary shifts result in higher trophic positions. Intraspecific studies based on δ15N values found a positive relationship between size and inferred trophic position. Here, we use datasets of predatory vertebrate ectotherms (crocodilians, turtles, lizards and fishes) to show that, although there are positive intraspecific relationships between size and δ15N values, relationships between stomach-content-based trophic level (TPdiet) and size are undetectable or negative. As there is usually no single value for 15N trophic discrimination factor (TDF) applicable to a predator species or its prey, estimates of trophic position based on δ15N in ectotherm vertebrates with large size ranges, may be inaccurate and biased. We urge a reconsideration of the sole use of δ15N values to assess trophic position and encourage the combined use of isotopes and stomach contents to assess diet and trophic level.

Natural vegetation biomass and the dimension of forest quality in tropical agricultural landscapes.

Forest cover has been a pivotal indicator of biological conservation and carrying capacity for wildlife in forest ecoregions. Such a relationship underpins policies focused on the extension of protected lands. Here, we estimate aboveground biomass (AGB) as a proxy for habitat quality in seminatural rural patches and provide a comparison with approaches that only consider forest cover. We hypothesize that recommendations for biological conservation in agricultural landscapes are substantially improved if habitat quality is also taken into account, and thus consider the possibility of forest quality being modulated by land-use amount, type, and age. We assessed AGB in a densely farmed Brazilian region using a straightforward approach designed to be affordable at large scales, focusing on two expanding and contrasting land uses: sugarcane, and eucalyptus plantations. At a detailed scale, we confirmed through field surveys and AGB estimation using 3D-multispectral imagery (i.e., AGB = 0.842 × vegetation heightNDVI+1) that AGB variation could be predicted with forest degradation classes that are visually distinguishable with high-resolution images: 9.33 t ha-1 (90% predictive intervals [PI] = [3.23, 26.97]) in regenerating fields (RF), 31.12 t ha-1 (90% PI = [10.77, 89.90]) in pioneer woods (PW), and 149.04 t ha-1 (90% PI = [51.59, 430.58]) in dense forests (DF). Applying these values to land units sampled across the study region, we found an average land use of 88.5%, together with 11.5% of land set aside for conservation, which reduced AGB to less than 4.2% of its potential (averages of 5.85 t ha-1 in sugarcane-dominated areas and 6.56 t ha-1 in eucalyptus-dominated areas, with secondary forests averaging 149.04 t ha-1). This imbalance between forest cover and AGB resulted from forest quality decay, which was similarly severe among land-use types, ages, and extensions. Therefore, the shortage of trophic resources is likely more critical to wildlife than spatial limitations in vastly deforested tropical ecoregions, where AGB and carbon sinks can be more than doubled just by restoring forests in lands currently spared by agriculture.

Non-invasive hair sampling of Neotropical otters / Coleta não invasiva de pelos de lontra Neotropical

Abstract: Sampling wild animal populations using non-invasive techniques is advised when dealing with threatened species. Hair samples provide ecological information like species and individual identification. However, hair trapping is scarcely used in otters, due to their aquatic habits. Most studies are with captive individuals, so there is the need to test non-invasive hair trapping methods in otters in the wild. The aim of this study was to develop a simple and cost-effective method to collect hair from otter species in a non-invasive way. The study was carried out in the Paranapanema River, São Paulo State, Brazil, with the Neotropical otter (Lontra longicaudis Olfers, 1818), a protected species. Hair traps (wooden sticks and tree roots with adhesive tape or wax bands) were set during six nights on river banks, otter trails and scent-marking sites. Traps were baited with otter fresh spraints from other river locations. From the 23 traps, 10 (43.7%) were successful in collecting otter hairs, mostly guard-hair. The sticks were much more efficient than the roots at capturing otter hair (70.6.% vs. 0%) as well as adhesive tape when compared to wax (71.4% vs. 0%). Method simplicity and efficiency suggest that it can be a cost-effective way for collecting otter hairs without the need for capturing individuals. This method can be used for: assessment of local otter distribution; collecting otter hair samples for sex and individual identification (by molecular analysis), trophic ecology (by isotopic analyses), ecotoxicology (by contamination analysis) or behaviour ecology (by hormonal and stress levels analysis). More trapping campaigns should be implemented to further test the method's efficiency.

Resumo: O uso de técnicas de amostragem não-invasivas é aconselhado quando se trabalha com espécies ameaçadas de animais selvagens. Amostras de pelo fornecem informações ecológicas, como a identificação ao nível da espécie e do indivíduo. No entanto, a coleta de pelo é pouco usada em lontras, devido aos seus hábitos aquáticos. A maioria dos estudos é feita com indivíduos em cativeiro, existindo por isso a necessidade de testar métodos não invasivos de coleta de pelos de lontras na natureza. O objetivo deste estudo foi desenvolver um método simples e com uma boa relação custo-benefício para coletar pelos de espécies de lontra de maneira não invasiva. O estudo foi realizado no rio Paranapanema, Estado de São Paulo, Brasil, com a lontra Neotropical (Lontra longicaudis Olfers, 1818), uma espécie protegida. Armadilhas de pelo (estacas de madeira e raízes de árvores com fita adesiva ou bandas de cera depilatória) foram colocadas durante seis noites nas margens do rio, em trilhas e locais de marcação de lontra. As armadilhas foram iscadas com dejetos frescos de lontra de outros locais do rio. Das 23 armadilhas, 10 (43.7%) foram eficazes na coleta de pelos de lontra, maioritariamente pelos-guarda. As estacas foram muito mais eficientes que as raízes na captura de pelos de lontra (70.6.% vs. 0%) tal como a fita adesiva quando comparada com a cera (71,4% vs. 0%). A simplicidade e a eficiência do método sugerem que esta pode ser uma maneira econômica de coletar pelo de lontra sem a necessidade de capturar indivíduos. Este método pode ser usado para: levantamento da distribuição local da lontra; coleta de amostras de pelo de lontra para identificação sexual e individual (por meio de análise molecular); ecologia trófica (por meio de análise isotópica); ecotoxicologia (por meio de análise de contaminantes); e ecologia comportamental (por meio da determinação de níveis hormonais reprodutivos e ligados ao estresse). Mais campanhas de armadilhagem devem ser implementadas para melhor avaliar a eficiência do método.

Microestruturas de pêlos de pequenos mamíferos não-voadores: chave para identificação de espécies de agroecossistemas do estado de São Paulo, Brasil / Microstructures of the hair of non-volant small mammals: key to the identification of species from agroecosystems of the State of São Paulo, Brazil

Hair microstructure characteristics have been used for species identification in taxonomic, ecological, paleontological, archeological and forensic research. This study aims to describe the hair structure from small mammals commonly found in agroecosystems of the São Paulo State. The hairs were collected from the dorsal region of previously identified specimens collected in agricultural areas (sugar-cane plantations), pasture areas, silviculture areas (eucalyptus plantation) and fragments of native vegetation (semideciduos Atlantic Forest and Cerrado). Optic microscope was not effective for describing the form and the border of scales, which were described using scanning electronic microscope. A dichotomic key of identification is presented for 11 species of non-volant small mammals (seven rodents and four marsupials).

Características microestruturais dos pêlos vêm sendo usadas para identificação de espécies em pesquisas taxonômicas, ecológicas, paleontológicas, arqueológicas e forenses. Este estudo tem como objetivo a descrição da estrutura dos pêlos de algumas espécies de pequenos mamíferos não-voadores comumente encontrados em agroecossistemas do Estado de São Paulo. Os pêlos foram coletados do dorso de espécimes previamente identificados coletados em áreas de agricultura (canavial), pastagens, silvicultura (plantio de eucalipto) e fragmentos de vegetação nativa (floresta semidecídua e cerrado). O microscópio óptico apresentou limitações para a descrição do formato e borda das escamas, os quais foram descritos através do uso de microscópio eletrônico de varredura. Uma chave de identificação dicotômica é apresentada para 11 espécies de pequenos mamíferos não-voadores (sete roedores e quatro marsupiais).

Primeiro registro de larvas de Chironomus inquinatus Correia, Trivinho-Strixino & Michailova (Diptera, Chironomidae) vivendo no casco do cágado Phrynops geoffroanus Schweigger (Testudines, Chelidae) na região Neotropical / First record of Chironomus inquinatus larvae Correia, Trivinho-Strixino & Michailova (Diptera, Chironomidae) living on the shell of the side-necked turtle Phrynops geoffroanus Schweigger (Testudines, Chelidae)

Neste estudo reportamos pela primeira vez a ocorrência de larvas de Chironomus inquinatus Correia, Trivinho-Strixino & Michailova vivendo no casco do cágado Phrynops geoffroanus Schweigger, possivelmente em função da intensa acumulação de sedimento, em um rio poluído da região Neotropical.

In this study we report for the first time the occurrence of Chironomus inquinatus larvae Correia, Trivinho-Strixino & Michailova living on the shell of the side-necked turtle, Phrynops geoffroanus Schweigger, possibly by the intense accumulation of sediment, in a polluted river of the Neotropics.

Detectability of capybaras in forested habitats / Detectabilidade de capivaras em habitats florestais

Direct count has been commonly used as an abundance index to estimate wildlife population size. However, systematic errors in sample-based estimators are common in sampling animal populations. At this study we aimed to estimate capybara's observability, through a detectability index in forested habitats. Sampling surveys of capybaras population was obtained by direct count (abundance index) and also by complete count (census). The average detectability index of capybaras in forested habitats was 0.63 ± 0.32 for a single observer. The variability in the detectability index among habitats was due to the presence of more or less dense vegetation. This information might be useful for management purposes of the species in the agroecosystems of southeastern Brazil where species is widespread and overabundant.

O método de contagem direta de animais tem sido freqüentemente utilizado como índice de abundância para estimar o tamanho de populações silvestres. Entretanto, erros sistemáticos de parâmetros baseados em amostras são comuns em amostragens de populações de animais silvestres. Neste estudo, nós estimamos a observabilidade de capivaras, através de um índice de detectabilidade em habitats florestais. As amostragens da população foram realizadas através da contagem direta (índice de abundância) e da contagem total (censo). O índice médio de detectabilidade de capivaras do observador em habitats florestais foi de 0,63 ± 0,32. A variabilidade no índice de detectabilidade entre os habitats ocorreu devido à vegetação ser mais ou menos densa. Esses resultados deverão ser úteis para o manejo da espécie em agroecossistemas do sudeste brasileiro onde a espécie é amplamente distribuída e abundante.

Cross-species microsatellite amplification in South American Caimans ( Caiman spp and Paleosuchus palpebrosus )

Microsatellite DNA markers have been used to assess genetic diversity and to study ecological behavioral characteristics in animals. Although these markers are powerful tools, their development is labor intensive and costly. Thus, before new markers are developed it is important to prospect the use of markers from related species. In the present study we investigated the possibility of using microsatellite markers developed for Alligator mississipiensis and Caiman latirostris in South American crocodilians. Our results demonstrate the use of microsatellite markers for Paleosuchus palpebrosus, Caiman crocodilus and Caiman yacare.

Relationship between body mass and body length in capybaras (Hydrochoerus hydrochaeris)

As a part of a management program we captured 39 capybaras (Hydrochoerus hydrochaeris) in an agroecosystem at the east central region of the State of São Paulo, Brazil from March 2001 to May 2002. Average adult male body mass was 54.1 ± 8.05 kg, and average adult female body mass was 62.0 ± 12.03 kg. Average juvenile male body mass was 23.0 ± 8.28 kg, and average juvenile female body mass was 26.7 ± 5.86 kg. Males and females presented a significant variation in the allometric relation between body mass and body length. Body mass and body length had a high correlation for both adult males and adult females. These results from capybaras in agroecosystem might be relevant for further management programs.

Trinta e nove capivaras (Hydrochoerus hydrochaeris) foram capturadas como parte de um programa de manejo em um agroecossistema na região centro-oeste do estado de São Paulo, de março de 2001 a maio de 2002. A massa corpórea média de machos adultos foi de 54.1 ± 8.05 kg, enquanto que de fêmeas adultas foi de 62.0 ± 12.03 kg. A massa corpórea média de machos jovens foi de 23.0 ± 8.28 kg, enquanto que de fêmeas jovens foi de 26.7 ± 5.86 kg. Machos e fêmeas apresentaram variação significativa na relação alométrica entre massa e comprimento corpóreos. Massa e comprimento corpóreos apresentaram alta correlação entre machos e fêmeas adultas. Estes resultados de capivaras em agroecossistemas podem ser importantes para futuros programas de manejo.

Microsatellite DNA library for Caiman latirostris.

New genetic markers were characterized for the broad-snouted caiman (Caiman latirostris) by constructing libraries enriched for microsatellite DNA. Construction and characterization of these libraries are described in the present study. One microsatellite marker was developed from a (ACC-TGG)(n)enriched microsatellite DNA library, and 12 microsatellite markers were developed from a (AC-TG)(n)enriched microsatellite DNA library. These markers were tested in wild-caught animals, and these tests resulted in ten new polymorphic microsatellites for C. latirostris.

Microgeographic variation in Caiman latirostris.

In theory, geographic scale is related to genetic variation at the population level, whereas microgeographic scale may reveal intra-population structure such as social groups and families. In the present work, both levels of genetic variation in the broad-snouted caiman (Caiman latirostris) were evaluated in small wetlands associated with the Piracicaba River and some of its tributaries in the state of São Paulo, Brazil. Genetic variation was determined using microsatellite DNA markers originally developed for the American alligator (Alligator mississipiensis) and previously tested in pedigreed captive broad-snouted caimans. Using these markers, we were able to detect variability among individuals from different sites, even those within a small geographic distance. Genetic results suggest that the groups sampled at each site are composed predominantly of related individuals. A possible combination of high mortality and low natality rates results in a low number of successfully dispersed individuals per generation. Future studies using a recently constructed Caiman latirostris microsatellite library (Zucoloto et al., 2002) might help us to understand metapopulation processes that may be occurring within this species.