Influence of Prey Size on the Capture of Social Wasps (Hymenoptera: Vespidae) by the Orb-Web Spider Nephilengys cruentata

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influence of Prey Size on the Predatory Behavior of Ectatomma brunneum (Hymenoptera: Formicidae) Under Laboratory Conditions

The influence of prey size on the predatory behavior and behavioral sequence of Ectatomma brunneum under laboratory conditions was evaluated. Two behaviors were characterized: rejection and attack, the latter divided into individual and group attack. In the group attack, prey transport (Tenebrio molitor larvae) into the nest prevailed, whether immobilized as a consequence of the ant venom or not. on the other hand, in the individual attacks such behavior was not observed. There was no significant relation between the predatory behavior and the size of the larvae offered, indicating that prey dimensions do not interfere with predation. The high rejection rates registered in the experimental trials may have been a consequence of the absence of immatures in the nests used in the research and/or the decrease in the activities observed, considering that the experiments were carried out in the coldest time of the year.

Birds of a central São Paulo woodlot: 1. Censuses 1982-2000

Foram listadas 263 aves próximo e dentro de uma mata semidecídua de 230 ha em meio a plantações de cana-de-açúcar, na região central do Estado de São Paulo, Brasil. Subtraindo-se 67 espécies de áreas abertas, 22 de riachos, 10 vagantes e 12 observadas mais tarde, cerca de 152 espécies de mata e de borda foram observadas entre 1982-86, semelhantemente às observadas em uma mata próxima a Campinas. Ambas as matas perderam espécies gradualmente. Algumas aves evitaram as margens duras dos canaviais, preferindo as margens macias arbustivas. Das espécies de área aberta, parece que 22 desapareceram até 1997, em razão das abundantes chuvas anteriores causadas por El Niño, ou pela raridade de habitats permanentemente abertos nos canaviais; 17 espécies novas eram principalmente noturnas que não haviam sido checadas anteriormente, ou visitantes ocasionais. A mata e as bordas perderam 37 espécies, ganhando 5 de regiões secas e 1 visitante de inverno. Vários migrantes do sul apareceram somente em anos chuvosos antes do recente efeito estufa; algumas aves residentes foram caçadas, e os beija-flores das copas talvez estivessem presentes ainda. As espécies de zonas secas, prones à movimentação ou metapopulacionais, movem os centros de distribuição, camuflando parcialmente a perda de diversidade da mata úmida.

Birds of a habitat spectrum in the Itirapina Savanna, São Paulo, Brazil (1982-2003)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Energetic and physiological correlates of prey handling and ingestion in lizards and snakes

In this review, we summarize the energetic and physiological correlates of prey handling and ingestion in lizards and snakes. There were marked differences in the magnitude of aerobic metabolism during prey handling and ingestion between these two groups, although they show a similar pattern of variation as a function of relative prey mass. For lizards, the magnitude of aerobic metabolism during prey handling and ingestion also varied as a function of morphological specializations for a particular habitat, prey type, and behavior. For snakes, interspecific differences in aerobic metabolism during prey handling seem to be correlated with adaptations for prey capture (venom injection vs. constriction). During ingestion by snakes, differences in aerobic metabolism might be due to differences in cranial morphology, although allometric effects might be a potentially confounded effect. Anaerobic metabolism is used for prey handling and ingestion, but its relative contribution to total ATP production seems to be more pronounced in snakes than in lizards. The energetic costs of prey handling and ingestion are trivial for both groups and cannot be used to predict patterns of prey-size selection. For lizards, it seems that morphological and ecological factors set the constraints on prey handling and ingestion. For snakes, besides these two factors, the capacity of the cardio-respiratory system may also be an important factor constraining the capacity for prey handling and ingestion. © 2001 Elsevier B.V.

Birds of Santa Teresa, Espírito Santo, Brazil: Do humans add or subtract species?

In uplands and lowlands of Santa Teresa, central Espírito Santo State, Brazil, 405 bird species were confirmed by field, museum, and literature studies. Of these, 16 seem to have disappeared, while 67 other species seem to have been lost from the lowlands (where no large biological reserves exist). Due to a suggestion that human areas add species to beta-diversity, we verified that up to 79 species now present have perhaps invaded with human activity (and 10 others are likely to invade), a total similar to that for lost species. However, lost species are often rare and invading species often widespread, resulting in exchange of Picassos for Coca-Cola bottles. Furthermore, gains exceed losses only when large biological reserves are present, as in the uplands (Nova Lombardia, Santa Lucia Reserves, each with over 250 species). Small or irregular reserves usually lose well over half their species, and these are only partly replaced by the invaders, resulting in net losses of up to half the local avifaunas. If one lists only 31 probable invaders, rather than a possible 79, things are even worse; net losses occur even in the entire township and near reserves, reaching over 200 species around lowland private reserves. Future productive development of human areas can eliminate or maltreat many invading species, too. While approving taxes on improductive use of land, as it leaves other areas free, we suggest that many current local uses, such as for coffee, are luxury production and could, be taxed.

Birds of a eucalyptus woodlot in interior São Paulo.

Some 255 birds were recorded between 1982-2001 in and near a 2314-ha Horto of old eucalyptus plantations with native understory and a lake, near Rio Claro, in central São Paulo, Brazil. This is close to the 263 recorded in and around a ten-times smaller nearby 230-ha woodlot of semideciduous forest. Different species were 44, for a total of 307 in both areas. One hundred and fifty nonvagrant forest and border species were recorded in 1982-86, a number close to the 152 in the small native woodlot. With dry years and logging of plots in 1985-93, 21 of the 150 species were lost, 42 species decreased in numbers, 49 were stable, 19 increased (15 being border species), and 5 entered (one of dry forest and 4 of borders), so 129 species remained in 1996-2001 compared to 133 in the native woodlot. Open-area birds were 33, versus 50 in better-checked grassy swales in sugar cane near the natural woodlot, for a total of 53. Several species, like some border ones, did not enter the open but isolated and mowed interior lake area, or took years to do so. Water and marsh birds were 46 versus 40 in smaller creeks and ponds near the natural woodlot (total, 55) but many were migrants or infrequent visitors using distant areas, and perhaps should be counted as 0.1-0.9 local species rather than 1 species. Use of this more accurate method would reduce waterbird totals by 14 species in the Horto and by 11 around the native woodlot. I also recommend longer censusing at the edges in large woodlots or many edge species will be recorded only in small fragments of habitat. Several species increased and others decreased with occasional cat-tail and water-lily cleanups at the lake. A forested corridor between the Horto and natural woodlot is recommended, with old eucalyptus left to provide flowers for hummingbirds.

Seed dispersal of Attalea phalerata (Palmae) by Crested caracaras (Caracara plancus) in the Pantanal and a review of frugivory by raptors

We observed Crested caracaras (Caracara plancus) consuming and dispersing fruits of the palm Attalea phalerata at Pantanal, Brazil. We reviewed the literature of seed dispersal by raptors and suggest that raptors may affect seed dispersal by three different paths: secondary seed dispersal by preying on frugivorous birds, primary seed dispersal of ornithocoric fruits and primary seed dispersal of large, lipid-rich fruits. The latter path may be an important long-distance seed dispersal mechanism for large seeds.

Effect of prey concentrations and feed training on production of Hoplias lacerdae juvenile

The aim of this work was to investigate the s of daily prey concentration during the first 15 days of active feeding of Hoplias lacerdae larvae, and the juvenile size on the feed training. In the first phase, the larvae received five Artemia nauplii concentrations (P). In the second phase, the juveniles from each treatment were trained to accept formulated diet. Superior growth was related to higher initial daily prey concentrations (900 and 1100 nauplii larvae-1). During feed training, the growth tendency was similar to that verified in the first phase. The lowest values of specific growth rate (SGR) were registered after the introduction of the semi-moist diet used in the feed training. However, the values of SGR recovered along the experiment and similar rates were found among the treatments. Survival, mortality and cannibalism were similar in the different treatments at the end of both phases. It can be concluded that: the prey concentration affects growth of H. lacerdae during the first 15 days of active feeding, and feed training can be initialized with juveniles of about 16 mm of total length.

Book Review of Birds of the Great Plains by Bob Jennings, Ted T. Cable, and Roger Burrows

Though intended as a field guide to the birds of the Great Plains, this book seems to serve best as a general introduction to Great Plains birds and will mostly benefit those casually interested in birds. The definition of Great Plains the book uses is rather broad, and some species are included that, in my opinion, aren't really birds of the Great Plains. For example, several warblers are included as breeding species although they nest within the book's definition of the region only in the conifer or mixed forest of north-central to northwestern Minnesota, which isn't really a part of the Great Plains proper.

Influence of Prey Size on the Capture of Social Wasps (Hymenoptera: Vespidae) by the Orb-Web Spider Nephilengys cruentata

The objective of the present study was to evaluate the plasticity of the hunting behavior of the spider Nephilengys cruentata (Araneae: Nephilidae) facing different species of social wasps. Considering that wasps can consume various species of spiders and that their poison can be used as defense against many predators, the effect of the corporal size of the prey was evaluated in the behavior of N. cruentata. Predation experiments were conducted using three species of social wasps of different sizes and the data registered in this research were compiled through annotations and filming of the hunting behavior of each spider, in relation to the offered prey. The results revealed that the size of the wasp and the sequential offer of prey change the hunting behavior of the spider, and prey of large size have high influence on this behavior.

Population size of threatened and endemic birds of the Cerrado in Estacao Ecologica de Itirapina, a fragmented area in the State of Sao Paulo, Brazil

The pressures for land use change have led to an increasing isolation of habitat remnants throughout the world. The goal of this study was to estimate the population size and density of some endemic and threatened species in a nature reserve in the Cerrado biome. One hundred and thirty four point transects were undertaken at the Estacao Ecologica de Itirapina (EEI), one of the last natural grassland savannah remnants in Sao Paulo state, in the south-east of Brazil between September and December 2006 and densities estimated for seven species (four endemic to the Cerrado, one near-endemic and two grassland specialists). Neither species reached the minimum viable population size of 500-5000 individuals. Four species, White-banded Tanager, White-rumped Tanager, Black-throated Saltator and Sharp-tailed Tyrant have populations ranging from 112 to 248 individuals, while the other species have a low population (< 60 individuals). The mean densities of Sharp-tailed Tyrant and Cock-tailed Tyrant in the EEI grassland showed similar values to those observed in larger areas of the Cerrado, which may indicate that the EEL grassland area is well conserved. In spite of the restricted size of the EEI, small areas can maintain some endemic and threatened bird populations, thus contributing to local biodiversity and the ecological processes in the region. The capacity of fragments of Cerrado (similar to 2,000 ha) to maintain populations of endemic and threatened bird species is unlikely to be effective in the long term.