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Nests of Schneider’s dwarf caiman,Paleosuchus trigonatus, were located in the forests around three streams that drain into the Xingu River, Brazilian Amazonia, in October 2014. Camera traps were installed at the edge of four nests to document predators and female parental care. At two nests, females unsuccessfully defended their nests against one or more giant armadillos,Priodontes maximus, and nine-banded armadillos,Dasypus novemcinctus. Both armadillo species responded to the attack by fleeing and returning on the opposite side of the nest by going around the tree under which the nest was located. Giant armadillos have never before been recorded consuming caiman eggs and their diet has been described as consisting mostly of ants and termites. Another species of armadillo,Cabassous unicinctus, was also registered digging into a nest and probably consuming eggs, though it is generally considered to be primarily insectivorous. A tayra (Eira barbara), lizard (Tupinambis teguixin) and coati (Nasua nasua) were also registered taking eggs from nests during the day, but we obtained no registers of nest defence by caimans during the day. The three nests were attacked after 60 days of incubation, when the eggs were well developed. [ABSTRACT FROM AUTHOR]

The giant otter (Pteronura brasiliensis) is a social species that defends territories along water bodies. Although some researchers have visually monitored otters during long periods at night, no nocturnal activity of the species has been recorded and giant otters are currently believed to be strictly diurnal. In this study, we present information about the activity patterns of groups of giant otters in the Brazilian Pantanal, using radio telemetry and camera trap data. We captured, implanted transmitters in, and monitored three male giant otters from different groups in the Miranda and the Vermelho Rivers between November 2009 and June 2011. The locations and behavior of the group were recorded at 30-min intervals from 05:00 to 19:00. Camera traps were positioned at the active dens and latrines of eight groups of giant otters in the Miranda, Vermelho and Negro Rivers between June 2010 and October 2011. The groups of giant otters were mostly crepuscular and diurnal, but 31% of the camera-trap recordings were nocturnal. Fishing was the most frequent (64%) behavior recorded by telemetry. Giant otters were recorded exiting the den mostly in the early morning (06:00) and entering the den at the end of the day (16:00 to 19:00). Nocturnal activity appeared to be associated with the need to defecate, prey availability nearby the den and predation risk. [ABSTRACT FROM AUTHOR]

The relationship between the distribution of predators (fish, odonates and water beetles) and prey assemblages (amphibian larvae) was investigated in the tropical rainforest of central Amazonas, Brasil. Theanuran community uses a variety of waterbodies for reproduction, ranging from streams and streamside ponds to isolated forest ponds. Predators in this system include fish in streams and streamside ponds, and invertebrates (primarily odonate naiads and beetles) in forest ponds. Tadpole species richness and assemblage structure were related to fish density and species richness. No relationships between tadpole assemblages and abiotic pond characteristics were detected. The presence of fish explained much of the variation in both species composition and species richness within and among ponds. Some species of tadpole were consistently found to coexist with high densities of fish. Path analyses suggest that while fish have a strong direct effect on tadpole associations and species richness, they also have an indirect effect through invertebrate predators (odonate larvae and coleopteran beetles). Prey survival-strategies such as palatability and behaviour may explain how tadpole species composition is affected by predators at the community level. These findings suggest that the observed patterns of habitat use by larval anurans may be structured in response to the distribution of key predators (fish) in this system. [ABSTRACT FROM AUTHOR]