Semideciduous Atlantic Forest mammals and the role of the Paraná River as a riverine barrier

The role of the Paraná River as an effective barrier for mammalian dispersal was evaluated. Four species were analyzed based on their characteristics and distributions along river margins: Caluromys lanatus (Didelphimorphia), Hylaeamys megacephalus, Oecomys bicolor (Rodentia), and Alouatta caraya (Atelidae). Considering their characteristics of small body sizes, arboreal life styles (of most species), and distributions in both river margins, the Paraná River is suggested to be a weak geographic barrier for mammal dispersal. Key words: Alouatta caraya, Caluromys lanatus, Hylaeamys megacephalus, riverine hypothesis, semideciduous Atlantic forest.The role of the Paraná River as an effective barrier for mammalian dispersal was evaluated. Four species were analyzed based on their characteristics and distributions along river margins: Caluromys lanatus (Didelphimorphia), Hylaeamys megacephalus, Oecomys bicolor (Rodentia), and Alouatta caraya (Atelidae). Considering their characteristics of small body sizes, arboreal life styles (of most species), and distributions in both river margins, the Paraná River is suggested to be a weak geographic barrier for mammal dispersal. Key words: Alouatta caraya, Caluromys lanatus, Hylaeamys megacephalus, riverine hypothesis, semideciduous Atlantic forest

Dieta de quatro espécies de pequenos mamíferos em fragmentos de floresta atlântica no sul do Brasil

In this study we analyse the diet composition of small mammals of western Paraná state, southern Brazil. Species studied were mostly unknown on feeding habits. Animals were sampled during the faunal survey carried out in October 1998 when implementing the Salto Caxias dam. The diet composition, based on gut contents, seems to be mostly opportunistic and generalist for the three marsupials, Micoureus paraguayanus, Caluromys lanatus, and Monodelphis sorex, and for the rodent, Akodon paranaensis, studied. Caeca of the four small mammal species had in general a small quantity of insects when compared with other digestive tract portions. However, when volume consumed was evaluated, Arthropoda was the most important item for three species of them. Inversely, fruits were important for C. lanatus. The estimated amount of plant material (seeds and other plant structures) had a higher importance for C. lanatus, mainly for caecum samples, however these items were also found in the other mammal species samples but in lower proportions. The high proportion of intact seeds on both, digestive tract and caecum, when compared with predated seeds, is noticeable, suggesting that the species are seed dispersal. Monodelphis sorex seems to have a more insectivorous diet, as it is a small cursorial mammal, although there was also evidence for frugivory or carnivory. Akodon paranaensis was insectivorous-omnivorous, although fruits and vertebrate prey were also consumed, indicating also and opportunistic diet. Caluromys lanatus is classifi ed as a more frugivorous species, besides the consumption of vertebrate prey. Insectivorous habit seems to be frequent in neotropical small mammals, with consumption of vertebrates or fruits being only opportunistic. The insectivory (except for C. lanatus) and opportunistic habit appear to dominate among the small mammal species studied. Key words: Micoureus paraguayanus, Caluromys lanatus, Monodelphis sorex, Akodon paranaensis, food habits.A composição da dieta de quatro espécies de pequenos mamíferos foi estudada no oeste do Paraná, sul do Brasil. Os animais foram amostrados durante o resgate de fauna ocorrido em outubro de 1998, durante a implementação da usina hidrelétrica de Salto Caxias. Os animais foram sacrificados logo após suas capturas. As análises foram baseadas nos tratos digestórios das espécies. As espécies Caluromys lanatus, Micoureus paraguayanus, Monodelphis sorex (Marsupialia) e Akodon paranaensis (Rodentia) se mostraram heterogêneas quanto à composição da dieta, tanto para itens animais quanto vegetais. Os cecos das quatro espécies tinham em geral uma menor proporção de insetos quando comparados às demais partes do trato digestório. No entanto, quando avaliado o volume consumido de cada item alimentar, os artrópodes foram mais importantes na dieta de três espécies de pequenos mamíferos do que frutos. Estes foram mais importantes para C. lanatus. A quantidade estimada de vegetais (sementes e estruturas vegetativas) foi muito mais importante para C. lanatus, principalmente no material retirado do ceco. Ressalta-se ainda a grande proporção de sementes inteiras tanto no trato digestório como nos cecos em todas as espécies estudadas, em comparação com a proporção de sementes predadas, evidenciando estas espécies como dispersoras de sementes. Monodelphis sorex parece ter uma dieta mais insetívora, por ser um pequeno mamífero cursorial, contudo há a evidência de frugivoria ou carnivoria para a espécie. Akodon paranaensis mostrou-se como insetívoro-onívoro, contudo frutos e presas vertebradas também foram consumidos, indicando também uma dieta oportunista. Caluromys lanatus foi classificado como a espécie mais frugívora, embora tenha consumido vertebrados. O hábito em geral insetívoro observado é freqüente em pequenos mamíferos neotropicais, com o consumo de vertebrados ou frutos de forma oportunista. A insetivoria, exceto para C. lanatus, e hábito alimentar oportunista parecem dominar entre os pequenos mamíferos estudados. Palavras-chave: Micoureus paraguayanus, Caluromys lanatus, Monodelphis sorex, Akodon paranaensis, hábitos alimentares

Spatial, dietary and temporal niche dimensions in ecological segregation of two sympatric, congeneric marsupial species

Didelphis aurita and D. albiventris are widely distributed in South America, with a range of sympatry in the limit of their distribution, particularly in Araucaria mixed ombrophilous forest in the southern Atlantic Forest. We investigated the spatial, feeding, and time use between these morphologically similar species in a remnant of Araucaria forest in southern Brazil for one year. We tested the hypothesis that these species when in sympatry segregate each other in space use, diet, and/or activity time. We expect that they segregate between each other primarily in the dimension of space use, as occurs for Australian congeneric marsupials. We used a mark-capture-release protocol for obtaining data. We analysed the spatial segregation by measuring the distance of captures in relation to the remnant centre, stream and edges. There were significant differences in the use of space, as adult females of D. aurita used mainly the remnant interior and stream sides, and D. albiventris females its edges or open areas. The consumption of feeding resources, particularly fruits, was different mainly between females and during the breeding season. However, there was no difference in the activity time between species. We believe that the territorial behaviour of D. aurita females had a crucial role in this spatial segregation with D. albiventris females, leading to a diet differentiation, particularly for fruits which were highly available inside the remnant. Interspecific competition between females is thought to be the main reason maintaining D. albiventris females far from the richest parts of the remnant. The mechanism behind this ecological segregation is discussed, and an ecological niche shift when both species are in sympatry is suggested, rather than the ghost of competition past. © Cáceres and Machado; Licensee Bentham Open

Mammals from Mato Grosso do Sul, Brazil

The aim of this paper is to provide a checklist of flying and non-flying mammal species which occur in the state of Mato Grosso do Sul, delimiting species by vegetation domains and vulnerability. Records were based on specimens in museums, literature, and only eventually on photos (by camera traps). There are 151 mammal species reported or collected in the state, comprising 10 orders and 29 families. The richest orders were Chiroptera (61 spp.), Rodentia (35), Carnivora (18), and Didelphimorphia (16). The richest families were Phyllostomidae (33 species), Cricetidae (23), Didelphidae (16), Molossidae (13), Vespertilionidae (9), Felidae (7), and Dasypodidae (6). Cerrado was the richest domain (117 spp.) followed by Pantanal (110). According to the Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis (IBAMA) and the International Union for Conservation of Nature (IUCN), 17 species are threatened; they are species of Felidae (n = 6), but also include Canidae (2), Didelphidae (2), Cervidae (1), Dasypodidae (1), Dasyproctidae (1), Mustelidae (1), Myrmecophagidae (1), Phyllostomidae (1), and Tapiridae (1)

Manipulação de frutos da palmeira Syagrus romanzoffiana por vertebrados no sul do Brasil

A year-long study was carried out in a deciduous forest to examine the vertebrate manipulation on fruits of Syagrus romanzoffiana in southern Brazil. Eleven 50x50 cm-track traps (each one baited with ten ripe fruits) were placed monthly around 11 adult palm trees, totalling a sampling effort of 935 traps. The fruits removed (absent) or chewed (left in situ) by a given vertebrate species were counted for each trap. Three species of mammals and one bird were monitored. The coati (Nasua nasua) removed more fruits (N = 250; 50 %) than chewed (N = 130; 26 %), leaving intact 120 fruits (24 %). The dusky-legged guan (Penelope obscura) also removed more fruits (N = 107; 43 %) than chewed (N = 44; 18 %), leaving intact 96 (39 %). On the other hand, the opossum (Didelphis albiventris) removed 127 (13 %), but chewed 622 (63 %), leaving intact 236 (24 %). Similarly, the agouti (Dasyprocta azarae) removed 16 (12 %), and chewed 64 (49 %), leaving intact 51 fruits (39 %). Results are discussed in light of the roles of these vertebrate species in seed dispersal of S. romanzoffiana. Key words: Atlantic forest, Dasyprocta azarae, Didelphis albiventris, Nasua nasua, palm tree, Penelope obscura, seed dispersal, fruit removal.Este estudo teve a duração de um ano e avaliou a manipulação por vertebrados (três espécies de mamíferos e uma de ave) nos frutos da palmeira Syagrus romanzoffiana no sul do Brasil. Onze armadilhas de pegada de 50x50 cm (cada uma iscada com 10 frutos maduros) foram colocadas próximas a onze palmeiras adultas, totalizando um esforço amostral de 935 armadilhas. Os frutos removidos (ausentes) ou mastigados (deixados in situ) pelas espécies de vertebrados foram contabilizadas para cada armadilha. Três espécies de mamíferos e uma de ave foram monitoradas. O coati (Nasua nasua) removeu 250 frutos (50%), mastigou 130 (26%) e deixou intactos 120 frutos (24%). O jacu (Penelope obscura) também removeu mais frutos (N = 107; 43%) do que mastigou (N = 44; 18%), deixando intactos 96 frutos (39%). O gambá (Didelphis albiventris) removeu 127 (13%), e mastigou 622 (63%), deixando intactos 236 (24%). Similarmente, a cutia (Dasyprota azarae) removeu 16 (12%), mastigou 64 (49%), deixando intactos 51 frutos (39%). Os resultados são discutidos relacionando o papel das espécies de vertebrados na dispersão de sementes de S. romanzoffiana. Palavras-chave: Floresta Atlântica, Dasyprocta azarae, Didelphis albiventris, Nasua nasua, palmeira, Penelope obscura, dispersão de sementes, remoção de frutos

Fruit consumption, distance of seed dispersal and germination of solanaceous plants ingested by common opossum (Didelphis aurita) in southern Brazil

Les distances minimales de dispersion de quelques Solanacées ont été étudiées et des tests de germination de leurs graines provenant de fèces de Didelphis aurita effectués dans le sud du Brésil. Les animaux ont été capturés chaque semaine afin d'obtenir les fèces dans une zone urbaine entre février 1995 et janvier 1996. Les distances minimales de dispersion ont été mesurées par la distance minimale entre le point de collecte de chaque groupe de graines (provenant d'une fiente) et la plante en fruit de la même espèce la plus proche. Les graines de chaque fiente ont été comptées et une partie d'entre elles a été soumise à des tests de germination. La quantité moyenne de graines par lente variait de 9 à 33. Ces animaux sont des consommateurs opportunistes de Solanacées dont ils ne détruisent pas les graines. Les distances minimales moyennes de dispersion variaient de 40 à 82 m. Les graines de plantes distribuées dans des clairières et en faibles densités avaient tendance à avoir de plus grandes distances de dispersion. Ces résultats ont montré que ce marsupial est un important agent de dispersion de Solanacées dans le sud du Brésil

Skull shape and the demands of feeding: a biomechanical study of peccaries (Mammalia, Cetartiodactyla)

A primary requirement of the mammalian skull is to exert forces on different foods and to resist the forces imposed on it during feeding. Skull shape patterns within and among mammals are generally well known, but the biomechanical relevance of this variation remains limited for some groups. By integrating geometric morphometric and biomechanical analyses, we test the hypothesis that skull shape in peccaries reflects biomechanical attributes to generate and dissipate powerful forces, presumably in response to tough foods. We obtained skull shape and size from 213 specimens of the three living peccary species and estimated bite force, bite stress at molars, bending and shear stress on the mandibular corpus, and condylar stress. We found larger estimated bite forces, greater resistance to bending loads, and lower stress emerging from the larger muscle attachment areas and shorter and deeper mandibular corpora for both Pecari tajacu and Tayassu pecari relative to Parachoerus wagneri. Peccaries (P. tajacu and T. pecari) with more powerful biomechanical attributes feed mainly on tougher foods (e.g., palm fruits). These results support the hypothesis that species eating tough foods tend to have a feeding morphology mechanically adapted to stronger bites and greater biting resistance, which must be closely reflected in their craniomandibular shape.Um requerimento primário do crânio de um mamífero é exercer forças em diferentes alimentos e resistir às forças impostas nele durante a alimentação. Os padrões de forma do crânio dentro e entre mamíferos são geralmente bem conhecidos, entretanto a relevância biomecânica desta variação permanece limitada a alguns grupos. Integrando análises de morfometria geométrica e de biomecânica nós testamos a hipótese de que a forma do crânio de tayassuídeos reflete atributos biomecânicos para gerar e dissipar forças de grande magnitude, tal como em resposta à alimentos duros. Nós obtivemos a forma e o tamanho do crânio de 213 espécimes das três espécies de tayassuídeos viventes e estimamos a força de mordida e o stress nos molares, no corpo mandibular e no côndilo. Nós encontramos maiores forças de mordida e de resistência e baixo stress emergindo de áreas mais amplas de inserção muscular e de corpos mandibulares mais curtos e altos de Pecari tajacu e Tayassu pecari em relação a Parachoerus wagneri. Tayassuídeos (P. tajacu and T. pecari) com atributos biomecânicos mais poderosos se alimentam principalmente de alimentos duros (por exemplo, frutos de palmeiras). Estes resultados suportam a hipótese de que espécies que se alimentam de alimentos duros tendem a apresentar uma morfologia do aparato alimentar mecanicamente adaptada a mordidas fortes e grande resistência de mordida, que deve estar intimamente associada as suas formas craniomandibulares.Facultad de Ciencias Naturales y Muse