ABSTRACT
@#Chigger mites are arthropods and are the sole vectors of scrub typhus, and rodents as well as other small mammals are the most common hosts of chigger mite larvae. Therefore, it is of great medical significance to study the ecology of chigger mites. In this study, a detailed analysis of chigger mites was conducted based on field survey data. A total of 4,941 chigger mites were collected from 86 hosts at 34 survey sites in Ruili, Yunnan Province, China. Among the 4,941 chiggers, five genera in one subfamily were identified; Schoengastiella ligula was the dominant chigger species with the highest infestation index, prevalence (Pm, 42.86%) and mean intensity (MI, 59.09%) (P<0.001). The association coefficient (V) between S. ligula and Gahrliepia radiopunctata was positively correlated (P<0.05), indicating the tendency of chiggers to select and coexist on the same host at the same time. The dominant species Leptotrombidium kunmingense, Ascoschoengastia indica, S. ligula and G. radiopunctata showed aggregation distribution patterns, indicating that the distribution of chiggers among different hosts was not uniform. Low altitudes and low latitudes appeared to be more favorable for the growth and reproduction of chigger mites (P<0.05). It is suggested to collect as many host samples as possible in future field investigations to better understand the dynamics of chigger mite populations and their primary hosts.
ABSTRACT
Abstract: Unusual movements of an animal can potentially represent a dispersal event. A higher frequency of young males dispersing is a pattern observed for most part of polygynous or promiscuous mammals with these dispersion events occurring, mainly, before or at the beginning of the breeding season. The water opossum (Chironectes minimus), the only marsupial adapted for semi-aquatic life, occurs from Mexico to Argentina and it has been mostly described as a sensitive species to river and riparian vegetation degradation, occurring exclusively near water curses. Here we describe the first record of long-distance movement of a water opossum not associated with riverine vegetation through dry land. We captured a healthy adult male of C. minimus in July 2012 beside of a highway (DF-001) located 1,100 m from nearest gallery forest in the Federal District. The region is characterized by urban and suburban residential, small fragments of typical savanna and degraded gallery forests. Our unique record could be an event of dispersion through degraded dry lands as observed for other semi-aquatic mammals and also suggests that this species is more resistant to anthropogenic disturbances than previously described. Also, information about dispersal patterns of water opossum is scarce and may contributes to a deeper understanding of ecological requirements of this species.
Resumo: Deslocamentos incomuns realizados por um animal podem representar potencialmente um evento de dispersão. Grande parte dos mamíferos poligínicos ou promíscuos, apresentam uma maior frequência de machos jovens dispersando, e esses eventos ocorrem, principalmente, antes ou no início da estação reprodutiva. A cuíca d'água (Chironectes minimus), único marsupial adaptado à vida semiaquática, ocorre do México à Argentina. Tem sido descrito principalmente como uma espécie sensível à degradação de cursos d'água e matas ciliares, ocorrendo exclusivamente próximo aos cursos d'água. Desta forma, descrevemos aqui o primeiro registro do deslocamento de longa distância de uma cuíca d'água não associado à vegetação ribeirinha através de um ambiente seco. Capturamos um macho adulto saudável de C. minimus em julho de 2012 à margem de uma rodovia (DF-001) localizada a 1.100 m da mata de galeria mais próxima no Distrito Federal. A região é caracterizada por residências urbanas e suburbanas, pequenos fragmentos de cerrado sentido restrito e matas de galeria degradadas. Nosso registro singular pode ser um evento de dispersão através de ambientes secos antropizados, conforme observado para outros mamíferos semiaquáticos, o que, também, sugere que esta espécie é mais resistente a distúrbios antropogênicos do que descrito anteriormente. Além disso, as informações sobre os padrões de dispersão da cuíca d'água são escassas e podem contribuir para um entendimento mais profundo dos requisitos ecológicos desta espécie.
ABSTRACT
Less than 10% of the original Atlantic Forest cover now remains standing in the Brazilian state of Sergipe, although few scientific studies have focused on its mammalian diversity. The present study describes the diversity of non-volant mammals found in the Ibura National Forest (INF), based on live trapping, and direct and indirect observations. We sampled the IBF on six days per month between June 2012 and August 2013, using live-traps (Sherman-type) positioned in pairs (ground and understory). We equally sampled semideciduous forest and an abandoned Eucalyptusplantation with dense understory (over 30 years). We also used non-systematics methods (direct observations, vestiges, camera-trap, and opportunistic captures). We recorded 18 species, from 12 families and 7 orders considering all the applied methods. Among recorded species, Bradypus torquatusand Lontra longicaudisare considered threatened of extinction. Considering only the live-trapping (totaling 3,240 trapping nights), we captured 125 individuals (3.85% success) from four species, Marmosa demerarae(52%), Didelphis albiventris(19.2%), Cerradomys vivoi(15.2%), and M. murina(13.6%). Estimated and observed richness was the same, suggesting a satisfactory effort. Didelphis albiventrisand M. demeraraeshowed significantly higher captures in the dry seasons. Didelphis albiventrisand C.vivoishowed significantly higher captures in the substratum, and M. demeraraehigher in the understory. Cerradomysvivoishowed significantly higher captures in the Eucalyptusphytophysiognomy. Non-Metric Multidimensional Scaling and the ANOSIM showed a significant difference in the captured species among semidecidual forest and Eucalyptus. Despite the small area (144 ha), the INF still houses a relatively high mammalian diversity. Further investigations may help to understand the role of habitat reduction in the diversity and habitat partitioning among mammal species in the Atlantic Forest of Northeastern Brazil.
Subject(s)
Animals , Biodiversity , Ecosystem , Mammals/anatomy & histology , Protected Areas/analysisABSTRACT
Abstract Small mammals play an essential role in the transmission and maintenance cycles of Borrelia spirochetes. In Chile, recent studies have characterized novel Borrelia genotypes in ticks collected from small mammals, a fact that suggests these vertebrates are hosts for spirochetes from this genus. Considering this evidence, the goal of this study was to determine the presence of Borrelia DNA in small mammals inhabiting northern Chile. In winter of 2018, 58 small mammals were captured in five localities. Blood samples were collected from rodents and DNA was extracted to determine the presence of Borrelia DNA by PCR targeting the flaB gene and rrs-rrlA intergenic spacer (IGS). From three individuals (5%), belonging to two rodent species of Cricetidae family (Phyllotis xanthopygus and Oligoryzomys longicaudatus), we retrieved three flaB and two IGS Borrelia genotypes. Phylogenetic analyses performed with both Maximum Likelihood and Bayesian inferences showed that our sequences grouped with homologous genotypes from the relapsing fever and Lyme borreliosis groups. Our findings suggest that P. xanthopygus and O. longicaudatus rodents may play a role as reservoirs for borrelial spirochetes in Chile.
Resumo Pequenos mamíferos possuem um papel essencial na transmissão e manutenção de espiroquetas do gênero Borrelia. No Chile, estudos recentes têm descrito novos genótipos de Borrelia em carrapatos, parasitando pequenos mamíferos. Isso sugere que esses vertebrados podem atuar como possíveis reservatórios dessas espiroquetas. Considerando-se essa evidência, o objetivo deste estudo foi determinar a presença de DNA de Borrelia em pequenos mamíferos da região norte do Chile. Durante o inverno de 2018, 58 pequenos mamíferos foram capturados em cinco localidades. Amostras de sangue obtidas a partir dos indivíduos capturados foram submetidas à extração de DNA e ensaios de PCR, para a detecção de Borrelia spp. baseados no gene flaB e espaçador intergênico rrs-rrlA (IGS). A partir de três espécimes (5%) pertencentes a duas espécies de roedores da família Cricetidae (Phyllotis xanthopygus e Oligoryzomys longicaudatus) obtiveram-se três genótipos de Borrelia para o gene flaB e dois para IGS. Análises filogenéticas inferidas, usando-se os métodos Bayesiano e de Máxima Verossimilhança, indicaram que as sequências geradas neste estudo agrupam-se com borrelias do grupo da Febre Recorrente e Borreliose de Lyme. Os achados deste estudo sugerem que roedores P. xanthopygus e O. longicaudatus poderiam atuar como possíveis reservatórios para Borrelia spp. no Chile.
Subject(s)
Animals , Rodentia/parasitology , Borrelia/classification , Borrelia/genetics , Ixodes/microbiology , Phylogeny , DNA, Bacterial/genetics , Chile , Bayes TheoremABSTRACT
En mamíferos silvestres los patrones de coloración atípica como el albinismo ocurren en baja frecuencia y en la literatura científica sus reportes son escasos. Por lo cual los hallazgos de este tipo son importantes para comprender mejor este fenómeno. En el presente trabajo realizamos el primer reporte de albinismo para el cuy silvestre Cavia tschudii (Rodentia) en la costa central de Perú. Este hallazgo también representa el primer registro de albinismo para el género Cavia en el Neotrópico.
In wild mammals, atypical coloration patterns such as albinism occur at a low frequency and are poorly reported in the literature. Therefore, discovery of cases of coloration anomalies are important to better understand this phenomenon. Here, we describe the first reported case of albinism in Cavia tschudii "Wild Guinea Pig" from the central coast of Peru. This discovery also represents the first record of albinism for the genus Cavia in the Neotropics.
ABSTRACT
Abstract The helminth fauna and metacommunity structure of eight sympatric sigmodontine rodents were investigated at the Serra dos Órgãos National Park, an Atlantic Forest reserve located in the State of Rio de Janeiro, southeast Brazil. Rodents of the species Abrawayaomys ruschii, Akodon montensis, Blarinomys breviceps , Delomys dorsalis, Oligoryzomys flavescens, Oligoryzomys nigripes, Oxymycterus quaestor and Thaptomys nigrita were found infected with helminths. Akodon montensis presented the highest total helminth species richness, with six different species of helminths. The nematode Stilestrongylus lanfrediae was the most abundant and prevalent helminth species observed. The host-parasite network analysis showed little interactions among host species. Akodon montensis seems to act as a keystone-species in the rodent community. This species shared the nematodes Stilestrongylus aculeata with A. ruschii and Protospirura numidica criceticola with T. nigrita, and the cestode Rodentolepis akodontis with D. dorsalis. The congeners host species O. flavescens and O. nigripes shared the nematodes Guerrerostrongylus zetta and S. lanfrediae. The rodents B. breviceps and O. quaestor did not share any helminths with other hosts. The helminth metacommunity showed a random pattern on both infracommunity and component community levels, indicating different responses by each helminth species to the environmental gradient.
Resumo Foram investigadas a helmintofauna e suas estruturas da metacomunidade em oito roedores sigmodontíneos simpátricos ao longo do Parque Nacional da Serra dos Órgãos, uma reserva de Mata Atlântica no estado do Rio de Janeiro, Brasil. Roedores das espécies Abrawayaomys ruschii, Akodon montensis, Blarinomys breviceps, Delomys dorsalis, Oligoryzomys flavescens, Oligoryzomys nigripes, Oxymycterus quaestor e Thaptomys nigrita foram infectados por helmintos. Akodon montensis apresentou a maior riqueza total de espécies de helmintos, com seis espécies. O nematoide Stilestrongylus lanfrediae foi a espécie de helminto com maior abundância e prevalência. A análise de rede parasito-hospedeiro mostrou poucas interações entre as espécies hospedeiras e A. montensis atuou como uma espécie-chave na comunidade de roedores. Esta espécie compartilhou os nematoides Stilestrongylus aculeata com A. ruschii e Protospirura numidica criceticola com T. nigrita, e o cestoide Rodentolepis akodontis com D. dorsalis. As espécies congêneres O. flavescens e O. nigripes compartilharam os nematoides Guerrerostrongylus zetta e S. lanfrediae. Os roedores B. breviceps e O. quaestor não compartilharam helmintos com outros hospedeiros. A metacomunidade de helmintos mostrou um padrão aleatório em ambos os níveis, comunidade componente e infracomunidade, indicando diferentes respostas de cada espécie de helminto ao gradiente ambiental.
Subject(s)
Animals , Rodent Diseases/parasitology , Rodentia/parasitology , Helminthiasis, Animal/parasitology , Helminths/classification , Brazil/epidemiology , Forests , Prevalence , Helminthiasis, Animal/epidemiology , Helminths/isolation & purificationABSTRACT
In this article, authors review the current knowledge of Bartonella infection in small mammals including rodents, insectivores, bats and exotic small mammal pets and their vectors in Asia. Species of Bartonella are Gram-negative intracellular bacteria that infect erythrocytes of various mammalian and non-mammalian animals and mainly transmitted by blood sucking arthropod vectors. The genus Bartonella includes several species of important human diseases with severe clinical signs. Several new Bartonella species were isolated from rodents and other small mammals, and from human patients in Asia. Bartonella species are identified using standard polymerase chain reaction amplification and a sequencing targeting two housekeeping genes (gltA and rpoB) and the internal transcribed spacer fragment. Authors also discuss the implications in term of potential emerging zoonotic diseases.
ABSTRACT
In this article, authors review the current knowledge of Bartonella infection in small mammals including rodents, insectivores, bats and exotic small mammal pets and their vectors in Asia. Species of Bartonella are Gram-negative intracellular bacteria that infect erythrocytes of various mammalian and non-mammalian animals and mainly transmitted by blood sucking arthropod vectors. The genus Bartonella includes several species of important human diseases with severe clinical signs. Several new Bartonella species were isolated from rodents and other small mammals, and from human patients in Asia. Bartonella species are identified using standard polymerase chain reaction amplification and a sequencing targeting two housekeeping genes (gltA and rpoB) and the internal transcribed spacer fragment. Authors also discuss the implications in term of potential emerging zoonotic diseases.
ABSTRACT
The genus Oecomys Thomas, 1906 is currently composed of 16 species with unclear taxonomy and poorly known geographic limits. O. catherinae Thomas, 1909 is known to occur within the Brazilian Atlantic Forest from the states of Santa Catarina to Pernambuco (where the northernmost previously known specimen of Oecomys in the Atlantic forest was recorded), and along riverine forest into the Cerrado. To gain a greater understanding of its geographical and ecological distribution (mainly in Northeastern Brazil) and of its taxonomic characterization, we provide a short review of karyotypical and morphometrical data from specimens collected within the distribution range of the species. Specimens presented 2n = 60 and AN varying between 62 and 64. A table with external and cranial measurements of the analyzed specimens is provided. In this paper we also report the presence of O. catherinae in the semi-deciduous forests of the state of Paraíba, representing the northernmost records of the species in the Atlantic forest and thereby extending its known geographical limits.
Oecomys Thomas, 1906 é um gênero atualmente composto por 16 espécies reconhecidas que apresentam taxonomia e distribuições geográficas ainda incertas. O. catherinae Thomas, 1906 é a espécie que ocorre ao longo da Floresta Atlântica brasileira dos estados de Santa Catarina a Pernambuco, onde se encontra o registro prévio mais ao norte para Oecomys na Floresta Atlântica, e ao longo de florestas de galeria no Cerrado. Pretendendo esclarecer aspectos relacionados à distribuição geográfica e ecológica de O. catherinae, com ênfase na região nordeste do Brasil, e auxiliar na sua caracterização taxonômica, fornecemos um breve resumo de dados morfométricos e cariotípicos de indivíduos coletados em diversos trabalhos ao longo da área de ocorrência da espécie. Os espécimens apresentaram 2n = 60 e NA variando entre 62 e 64. Uma tabela de medidas corporais externas e cranianas dos indivíduos analisados é fornecida. Também registramos pela primeira vez a presença de O. catherinae nas florestas semi-deciduais do estado da Paraíba, sendo atualmente os registros mais ao norte da espécie na Floresta Atlântica, estendendo os limites geográficos conhecidos para a espécie.
ABSTRACT
The Atlantic forest of Brazil is nowadays reduced to less than 8% of its total original area and yet many species remain to be described. The Atlantic Forest north to the São Francisco river - The Pernambuco Endemism Center (CEPE) - has less than 2% of its original forest cover and yet the knowledge on small mammals is scarce. Aiming to assess the small mammal community of this region surveys were carried out in 12 forest fragments of different sizes in distinct geographic areas of the CEPE. The capture-mark-recapture technique was used with live-traps set along linear transects. We recorded 15 species, two of which are in the IUCN Red List, but not in the Brazilian List of Threatened Species. The highest richness and abundance indices were recorded in medium-sized fragments and in the rainy season. More marsupial species were recorded compared to rodents. Our results suggest that fragmentation caused the extinction of those most specialized species, currently remaining only those most tolerant to fragmentation and urbanization. It is recommended that urgent measures should be taken to reconnect and restore these fragments to allow recolonization and reestablishment of the gene flow among the populations.
A Floresta Atlântica do Brasil encontra-se hoje reduzida a menos de 8% da sua área original e contém várias espécies ainda desconhecidas. Sua porção ao norte do Rio São Francisco, o Centro de Endemismo Pernambuco (CEPE), possui atualmente menos de 2% de sua área original e o conhecimento sobre pequenos mamíferos é escasso. Com o objetivo de conhecer melhor a comunidade de pequenos mamíferos desta região foram realizados levantamentos em 12 fragmentos de diferentes tamanhos em áreas geográficas distintas do CEPE. A técnica de captura-marcação-recaptura foi utilizada, com armadilhas de captura viva dispostas em transectos ao longo dos fragmentos. Foram registradas 15 espécies, das quais duas estão inclusas na lista vermelha da IUCN, embora não na lista de espécies ameaçadas do IBAMA. Os maiores índices de riqueza e abundância foram encontrados nos fragmentos de tamanho médio, e durante a estação chuvosa. Foram registradas mais espécies de marsupiais do que de roedores. Os resultados sugerem que a fragmentação causou a extinção daquelas espécies mais especializadas, persistindo atualmente apenas aquelas mais tolerantes à fragmentação e urbanização. Recomendamos que medidas urgentes sejam tomadas para re-conectar e restaurar estes fragmentos, tornando possível sua re-colonização pelas espécies e o aumento do fluxo gênico entre as populações.
Subject(s)
Forests/analysis , Environmental Policy , Conservation of Natural Resources , Ecosystem/analysis , Ecosystem/classification , Mammals/classification , TreesABSTRACT
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).
Subject(s)
Archaeology , Classification , Ecological Studies , Mammals , Marsupialia , Paleontology , RodentiaABSTRACT
A community of small mammals was studied in seasonal semideciduous submontane forest in the state of Mato Grosso, Brazil. This study evaluated the use of edge and matrix pasture, by different small mammal species. Overall, 31 areas were studied, with a total sampling effort of 33,800 trap x nights. Only seven of the 25 species captured in the study sites were able to use the pasture matrix; we classified these species as generalists. Fourteen species were found to be intermediate in habits, being able to use forest edges. We found only four species habitat specialists, occurring only on transect lines in the interior of the fragment, at least 150 m from the edge. Transects located in the pasture matrix and 50 m from the edge had significantly lower species richness and abundance than transects located in the fragment edge or in the interior of the fragment. All transects located within the fragment had similar species richness and abundance, but transects located 50 m from the edge had slightly lower, but non-significant, species richness than transects located 100 m apart from edges. Rarefaction curves demonstrated that only medium-sized fragments (100 300 ha) reached an asymptote of species accumulation. The other areas require further sampling, or more sampling transect, before species accumulation curves stabilize, due to a continued increase in species number.
Uma comunidade de pequenos mamíferos foi estudada em fragmentos de floresta estacional semidecidual submontana no Estado de Mato Grosso, Brasil. Nesse estudo, buscou-se avaliar o uso da borda e da matriz de pastagem pelas diferentes espécies. No total, 31 áreas foram estudadas, com um esforço total de 33.800 armadilhas x noite. Apenas sete das 25 espécies capturadas foram capazes de utilizar a matriz de pastagem, sendo estas consideradas generalistas. Quatorze foram consideradas intermediárias no uso do habitat, sendo capazes de utilizar habitats de borda. Encontramos apenas quatro especialistas, ocorrendo somente nas transecções do interior do fragmento, a aproximadamente 150 m da borda. Dentre todas as transecções utilizadas para amostragem, a disposta na matriz de pastagem, a 50 m da borda, demonstrou ser significativamente menos rica e abundante que as dispostas na borda e no interior dos fragmentos. Todas as transecções localizadas dentro do fragmento tiveram riqueza e abundância de espécies similares, porém a transecção localizada a 50 m da borda teve uma tendência a ser menos rica que a transecção a 100 m. Através de ajustes das curvas de rarefação, somente uma das áreas considerada de médio porte, entre 100 a 300 ha., atingiu uma assíntota. As outras áreas necessitam de um maior número de transecções, a fim de se obter uma estabilização das curvas, pois continuaram a acrescentar espécies.
Subject(s)
Animals , Biodiversity , Ecosystem , Mammals/physiology , Trees , Brazil , Mammals/classification , Population DensityABSTRACT
We inventoried terrestrial small mammals in an agricultural area in southern Brazil by using trapping and prey consumed by Barn Owls (Tyto alba) and White-tailed Kites (Elanus leucurus). Small mammals were trapped in three habitat types: corn fields, uncultivated fields ("capoeiras"), and native forest fragments. A total of 1,975 small mammal specimens were trapped, another 2,062 identified from the diet of Barn Owls, and 2,066 from the diet of White-tailed Kites. Both trapping and prey in the predators' diet yielded 18 small mammal species: three marsupials (Didelphis albiventris, Gracilinanus agilis, and Monodelphis dimidiata) and 15 rodents (Akodon paranaensis, Bruceppatersonius iheringi, Calomys sp., Cavia aperea, Euryzygomatomys spinosus, Holochilus brasiliensis, Mus musculus, Necromys lasiurus, Nectomys squamipes, Oligoryzomys nigripes, Oryzomys angouya, Oxymycterus sp.1, Oxymycterus sp.2, Rattus norvegicus, and Rattus rattus (Linnaeus, 1758)). The greatest richness was found in the uncultivated habitat. We concluded that the three methods studied for inventorying small mammals (prey in the diet of Barn Owls, White-tailed Kites, and trapping) were complementary, since together, rather than separately, they produced a better picture of local richness.
Nós inventariamos a fauna de pequenos mamíferos terrestres numa área agrícola no sul do Brasil utilizando armadilhas e presas consumidas pela coruja suindara (Tyto alba) e pelo gavião-peneira (Elanus leucurus). Os pequenos mamíferos foram amostrados em três tipos de habitat: cultivos de milho, capoeiras e fragmentos de floresta nativa. Ao todo, 1975 espécimes de pequenos mamíferos foram capturados com armadilhas, 2062 identificados a partir da dieta da suindara e 2066 da dieta do gavião-peneira. Juntas, as capturas com armadilhas e presas identificadas na dieta de ambos os predadores revelaram 18 espécies de pequenos mamíferos: três marsupiais (Didelphis albiventris, Gracilinanus -agilis e Monodelphis dimidiata) e 15 roedores (Akodon paranaensis, Bruceppatersonius iheringi, Calomys sp., Cavia -aperea, Euryzygomatomys spinosus, Holochilus brasiliensis, Mus musculus, Necromys lasiurus, Nectomys squamipes, Oligoryzomys nigripes, Oryzomys angouya, Oxymycterus sp.1, Oxymycterus sp.2, Rattus norvegicus e Rattus rattus). A maior riqueza de espécies foi encontrada nas capoeiras. Nós concluímos que os três métodos estudados para inventariar a fauna de pequenos mamíferos (presas na dieta da suindara, do gavião-peneira e capturas com armadilhas) foram complementares, pois juntos forneceram uma idéia melhor da riqueza local do que individualmente.
Subject(s)
Animals , Biodiversity , Marsupialia/classification , Predatory Behavior , Rodentia/classification , Strigiformes/physiology , BrazilABSTRACT
A two year study of dung beetles and ants acting on scats of two species of opossum (Didelphis spp.) was carried out. Scats were left in the field in order to detect post-dispersal agents. A portion of each scat (30 %) was examined for seeds in the laboratory. Beetles were recovered from burrows (51% of 84 faecal samples left in the field) where they either buried scats of opossums or were attracted, together with ants, to pitfalls (N = 10) baited with opossum scats. Dung beetles were the main post-dispersal agents of seeds found in scats of opossums, rolling the scats away or burying then on the site of deposition. They buried faeces at 4 to 15 cm in depth (N = 22 tunnels). The main dung beetles identified (medium to large size) were Eurysternus (28.7 % in pitfalls) and Dichotomius (13.7 %), Coprophanaeus (seen only directly on faeces), besides small-bodied beetles (< 10 mm; 57.6 %). The ant Acromirmex sp. transported some seeds from scats. This species was present in 25.5 % of all Formicidae samples (pitfall). These post-dispersal agents contribute to avert scat seed predators such as rodents, and to accelerate seed bank formation.
Por dos años estudiamos los escarabajos coprófagos y las hormigas que actúan en las heces de zarigüellas (Didelphis). Se dejaron excrementos en el campo para descubrir los agentes secundarios de dispersión. Una parte de cada excremento (30 %) fue analizada en laboratorio para estimar el número de semillas. Se recolectaron escarabajos del suelo (51 % de 84 excrementos dejados en el campo). También capturamos escarabajos y hormigas con trampas (N= 10). Los escarabajos coprófagos son los principales agentes secundarios de dispersión. Ruedan los excrementos o los entierran a 4-15 cm de profundidad (N= 22 túneles). Los escarabajos coprófagos de mayor tamaño fueron Eurysternus cyanescens (28.7 % en trampas), Dichotomius assifer (13.7 %) y Coprophanaeus saphirinus (sólo visto en madrigueras y directamente sobre los excrementos). Los escarabajos de menos de 10 mm fueron el 57.6 %. La hormiga Acromirmex sp. fue 25.5 % del total de hormigas capturadas en trampas. Hallamos varias especies de semillas en los excrementos, muchos de ellos enterrados por los escarabajos, y algunas fueron extraídas por las hormigas. Estos agentes secundarios ayudan a evitar los depredadores de semillas (eg. roedores) y aceleran la formación del banco de semillas, pues no las comen.
Subject(s)
Animals , Coleoptera/physiology , Behavior, Animal/physiology , Ants/physiology , Opossums/physiology , Seeds/growth & development , FecesABSTRACT
Studies quantifying habitat structure generally use several instruments. This paper aims to propose a new and efficient device to characterize microhabitat structure of small mammals. Seven measurements were taken: plant cover, litter cover, rock cover, canopy cover, and vegetative obstruction at three heights. The device is a 0.25 m² square wooden frame (0.50 m x 0.50 m) divided in to 100 open squares by wire mesh. Average time spent to measure each trapping station was six minutes. This new device is efficient, i.e., quick, practical, simple, and reliable. It can be used in any kind of forest. We propose this method as a standard method to describe habitat structure.
Os estudos que quantificam a estrutura do habitat geralmente usam vários instrumentos. Este artigo objetiva propor um novo e eficiente instrumento para caracterizar a estrutura do microhabitat de pequenos mamíferos. Sete medidas foram tomadas: cobertura vegetal (herbáceos e lenhosos), cobertura de folhiço, cobertura de pedras, cobertura de dossel e obstrução foliar vertical em três alturas. O instrumento é uma tela quadrada de 0,25 m² (0,50 m x 0,50 m) de madeira, dividida por arame em 100 quadrados abertos. O tempo médio para medir cada estação de captura foi de 6 minutos. Este novo instrumento é eficiente, isto é, rápido, prático, simples e confiável. Ele pode ser usado em qualquer tipo de floresta. Propomos este método como padrão para descrever a estrutura do habitat.