Helena Godoy Bergallo

Effects of Climate and Food Availability on Four Rodent Species in Southeastern Brazil

Seasonal reproduction of small mammals in the tropics usually is related to annual cycles of rainfall. We examined effects of weather and food availability on reproduction and population ecology of Nectomys squamipes, Oryzomys intermedius, Akodon cursor and Trinomys iheringi . Each species was studied monthly from February 1993 to January 1995 using mark-recapture methods at Ilha do Cardoso, Sao Paulo State, Brazil. Average capture rate for each month was used as an index of population size, and survival rate was estimated by the Jolly-Seber method. Direct effects of food availability and rainfall were related to female reproductive activity and survival rate. Path analyses were used to describe quantitatively the hypothesized causal relations among the variables. N. squamipes reproduced seasonally, and O. intermedius, T. iheringi , and A. cursor reproduced all year with peaks during the rainy season. Species responded differently to the environmental factors; however, food availability seems to be the main factor determining reproduction. Abundance of rains appears to diminish survival rate of O. intermedius . Survival rate of N. squamipes increases with increases in fruit availability.

Ecology of a small mammal community in an Atlantic forest area in southeastern Brazil

During a 14 month mark‐and‐release project in an Atlantic forest area (Jureia Ecological Station), I studied the population ecology of 8 species of small mammals (3 marsupials and 5 rodents). In a 4,307 trap nights, 182 individuals were captured 650 times. The rodents were caught 73% of the total capture and the marsupials 27%. Oryzomys nitidus was the commonest species in the grid followed by Proechimys iheringi and Metachirus nudicaudatus. The marsupials showed a seasonal pattern of reproduction. As a consequence, the population densities had a peak during the wet months with the entrance of the youngs. The rodents, P. iheringi and O. nitidus bred throughout the year, although the former one had a peak in the dry months. Density of O. nitidus was fairly constant, whereas that of P. iheringi was higher during the recruitment time. Rodents and marsupials contributed with the same biomass in Jureia small mammal community.

Thermal biology and flight distance of Tropidurus oreadicus (Sauria Iguanidae) in an area of Amazonian Brazil

The thermal biology and flight distance of the tropical lizard Tropidurus oreadicus was studied on iron ore outcrops (called canga) at Serra dos Carajas, in Brazilian Amazonia. Body temperature varied markedly throughout the day (range 32.0 to 38.1 °C), but mean preferred body temperature was 35.8 °C. The air temperature in the microhabitat explained a considerable part of Tropidurus oreadicus body temperature variation, but other factors such as direct insolation and substratum teperature may also be of importance. In the morning, lizards usually climbed onto rocks and assumed progressively changing body orientations and inclinations which increased the interception of sunlight. Later they retreated to vegetation. This suggested that the importance of rocks as basking sites changes during the morning due to the angle of the sun. The flight distance was greater when body temperature was low and this may be of survival value in open areas such as the mineral outcrops of Serra dos Carajas.

Pattern of elevational distribution and richness of non volant mammals in Itatiaia National Park and its surroundings, in Southeastern Brazil

Itatiaia National Park (PNI) and its surroundings present a unique fauna due to different forest formations with well-defined climatic and vegetation bands. The Itatiaia massif has four vegetation types that follow an altitudinal gradient: lower montane forest, montane forest, upper montane forest, and Campos de Altitude. Hence, this region is ideal for studying geographical variation in biological diversity. The main objectives of this study were to report on nonvolant mammal species known to occur in Itatiaia National Park and its surroundings and to determine if their distributional pattern is related to elevation. A review of the literature and a complete survey of specimens deposited in museums, as well as small-mammal trapping were carried out in order to obtain a complete record of the species from the region. Precise locality data were obtained for all specimens recorded, allowing the inclusion of each collected or observed individual in an altitude and vegetational class. We made a direct ordination gradient of marsupial, primate, and rodent species abundance with the altitude. Sixty-nine mammal species were collected or reported for the Itatiaia massif, belonging to seven orders and 20 families. Of these, 33 species (47.8%) are included in the official list of threatened or believed-to-be threatened species in Rio de Janeiro State. The orders Rodentia, Carnivora, and Didelphimorphia had the highest species richness, with 25, 14, and 13 species respectively. When species were grouped according to the vegetation, 16 species occured in the lower montane, 56 in the montane forest, five in the upper montane, and 21 in the high-altitude fields (Campos de Altitude). The communities of marsupials, primates, and rodents have an ordination pattern related to the altitude. Species richness was higher between 500 m and 1,500 m above sea level in montane forest, which is in agreement with recent studies showing that species richness can reach its maximum at mid-elevations.

Activity patterns and body temperatures of two sympatric lizards (Tropidurus torquatus and Cnemidophorus ocellifer) with different foraging tactics in southeastern Brazil

Nos estudamos a biologia termal e comparamos os padroes termais e de atividade de dois lagartos simpatricos com diferentes taticas de forrageamento (Tropidurus torquatus e Cnemidophorus ocellifer) num habitat de restinga na Reserva Florestal Vale do Rio Doce, Linhares, Brasil. Os dados mostraram que as temperaturas corporais de ambas as especies relacionaram-se positiva e significativamente com a temperatura do substrato. A especie forrageadora ativa, C. ocellifer, teve temperaturas medias corporais significativamente maiores (37.6 ± 2.0°C) do que o senta-e-espera T. torquatus (35.6 ± 1.9°C), e permaneceu ativo no habitat numa porcao menor de tempo (entre 8:30 e 15:00 h) do que T. torquatus (entre 7:00 e 18:00 h). Nossos resultados estao de acordo com a premissa de que especies forrageadoras ativas teriam maiores temperaturas medias corporais e permaneceriam ativas no habitat por periodo de tempo relativamente mais curto do que especies forrageadoras sedentarias.

Seasonal variation in the diet of the bat Carollia perspicillata (Chiroptera: Phyllostomidae) in an Atlantic Forest area in southeastern Brazil

Carollia perspicillata feeds primarily on plants of the family Piperaceae, as reported in the literature. Although this preference occurs throughout this species’ geographic range, in some situations they may eat other items. This study analyzed variations in the feeding habits of this bat species over an 18-month period. Although C. perspicillata consumed mostly Piper plants, they also ate other fruits (e.g. Cecropia and Solanum plants), and insects as well. Food choice followed a seasonal pattern, related to the availability of Piper plants. The seasonal absence of these fruits may have necessitated bats to eat alternative items.

Bigger ant colonies reduce herbivory and herbivore residence time on leaves of an ant-plant: Azteca muelleri vs. Coelomera ruficornis on Cecropia pachystachya

SummaryThe effect of defence force size in colonies of the ant Azteca muelleri on the time spent to localize, attack and expel the specialized herbivorous beetle Coelomera ruficornis from Cecropia pachystachya bushes was studied in an area of Atlantic forest in northeastern Brazil. Our results show that Azteca muelleri expel Coelomera ruficornis from Cecropia pachystachya and that the number of ants leaving a colony (defence force size) is negatively correlated with the residence time of an adult beetle on the plant. Colonies with larger defence forces recruited larger numbers of ants, resulting in faster herbivore discovery (r2=0.80; n=17; P<0.001) and reduced herbivore residence time on a leaf (r2=0.79 n=23; P<0.001) before being driven off by the ants. We also found a negative and significant relationship between herbivore damage on leaves and ant colony size (r2=0.28; n=17; P<0.05). We conclude that larger colonies have more individuals available to patrol a plant and recruit defenders toward herbivores. This reduces the time spent to locate and expel susceptible herbivores from the plant. Since the plant probably benefits from reduced herbivory and the plant provides food for the ants, the association between Azteca muelleri and Cecropia pachystachya appears mutualistic.

Endemic and threatened tetrapods in the restingas of the biodiversity corridors of Serra do Mar and of the Central da Mata Atlântica in eastern Brazil.

Biodiversity corridors comprise a mosaic of land uses connecting fragments of natural forest across a landscape. Two such corridors have been established along the eastern coast of Brazil: the Serra do Mar and the Central da Mata Atlântica corridors, along which most of the coastal plains are restinga areas. In this study, we analyze the present status of the endemic and endangered terrestrial vertebrates of both corridors. We sampled 10 restingas in both corridors, recording species of amphibians, reptiles, birds, and mammals. Some restingas harbor a relatively large number of endemic species,and two main regions of endemism can be identified along the restingas of both corridors: the coastal restingas from northern Espirito Santo State to southern Bahia State (between Linhares, ES, and Tarancoso, BA), and the coastal region between the restingas of Maricá and Jurubatiba, Rio de Janeiro State. Six species of terrestrial vertebrates considered threatened with extinction are found in the restingas of Serra do Mar and Central da Mata Atlântica biodiversity corridors (Liolaemus lutzae, Formicivora littoralis, Mimus gilvus, Schistochlamys melanopis, and Trinomys eliasi). The region located between the restinga of Maricá and that of Jurubatiba is of special relevance for the conservation of vertebrate species of the restingas of the corridors because a considerable number of threatened species of terrestrial vertebrates are found there. We strongly recommend efforts to develop checklists of threatened faunas for the States of Espirito Santo and Bahia.

A test of the effects of climate and fruiting of Piper species (Piperaceae) on reproductive patterns of the bat Carollia perspicillata (Phyllostomidae)

Bats of the genus Carollia feed mainly on plants of the genus Piper, dispersing their seeds in all localities where they occur together. Interactions among these bats, their food plants, and the climate were studied in an Atlantic Forest area in Southeastern Brazil. Path analysis was used to estimate the strength of direct and indirect effects through which variables determine the timing of bat reproduction. Temperature had a small direct influence, but a strong indirect one. Rainfall affected bat reproduction through indirect ways. Although the consumption of Piper fruits by bats did not have a significant influence, the timing of production of Piper fruits was a strong variable directly affecting bat reproduction. We therefore suggest that Piper plants and climate may play a keyrole in the timing of reproduction in C. perspicillata bats.

Factors affecting the use of space by two rodent species in Brazilian Atlantic forest

The main purpose of this study was to determine whether the maximum distance traveled and home range area of Nectomys squamipes and Oryzomys russatus differ between sexes, breeding seasons and species. We also evaluated whether rainfall and food availability influenced the maximum distance traveled. Rats were trapped monthly from February 1993 to January 1995 in an area of Atlantic forest, Brasil. Maximum distance traveled by N. squamipes was not related to mass and was longer during the breeding season for males. There were no differences between seasons in the distances traveled by O. russatus, but larger males traveled further. Food availability and rainfall had no effect on the distance traveled by each species. Home ranges of male N. squamipes were larger than those of females during the breeding season, but home ranges did not differ between the sexes in O. russatus. Differences between the two species in movement may be related to differences in mating systems, which are probably promiscuous in N. squamipes and monogamous in O. russatus.