Effects of howler monkey reintroduction on ecological interactions and processes.

Rewilding has been an increasingly popular tool to restore plant-animal interactions and ecological processes impaired by defaunation. However, the reestablishment of such processes has seldom been assessed. We investigated the restoration of ecological interactions following the reintroduction of the brown howler monkey (Alouatta guariba) to a defaunated Atlantic forest site. We expected the reintroduction to restore plant-animal interactions and interactions between howlers and dung beetles, which promote secondary seed dispersal. We estimated the number of interactions expected to be restored by the reintroduction to provide the baseline interaction richness that could be restored. We followed the reintroduced howler monkeys twice a week for 24 months (337 hours total) to assess their diet. We used howler monkey dung in secondary seed dispersal experiments with 2484 seed mimics to estimate the removal rates by dung beetles and collected the beetles to assess community attributes. We compared the potential future contribution of howler monkeys and other frugivores to seed dispersal based on the seed sizes they disperse in other areas where they occur. In 2 years, howler monkeys consumed 60 animal-dispersed plant species out of the 330 estimated. Twenty-one dung beetle species were attracted to experimentally provided dung; most of them were tunnelers, nocturnal, and large-sized (>10 mm). On average 30% (range 0-100%) of the large seed mimics (14 mm) were moved by dung beetles. About 91% of the species consumed by howlers (size range 0.3-34.3 mm) overlapped in seed size with those removed by dung beetles. In our study area, howler monkeys may consume more large-seeded fruit species than most other frugivores, highlighting their potential to affect forest regeneration. Our results show reintroductions may effectively restore ecological links and enhance ecological processes.

Estimating interaction credit for trophic rewilding in tropical forests.

Trophic rewilding has been suggested as a restoration tool to restore ecological interactions and reverse defaunation and its cascading effects on ecosystem functioning. One of the ecological processes that has been jeopardized by defaunation is animal-mediated seed dispersal. Here, we propose an approach that combines joint species distribution models with occurrence data and species interaction records to quantify the potential to restore seed-dispersal interactions through rewilding and apply it to the Atlantic Forest, a global biodiversity hotspot. Using this approach, we identify areas that should benefit the most from trophic rewilding and candidate species that could contribute to cash the credit of seed-dispersal interactions in a given site. We found that sites within large fragments bearing a great diversity of trees may have about 20 times as many interactions to be cashed through rewilding as small fragments in regions where deforestation has been pervasive. We also ranked mammal and bird species according to their potential to restore seed-dispersal interactions if reintroduced while considering the biome as a whole and at finer scales. The suggested approach can aid future conservation efforts in rewilding projects in defaunated tropical rainforests.This article is part of the theme issue 'Trophic rewilding: consequences for ecosystems under global change'.

Living and lost mammals of Rio de Janeiro's largest biological reserve: an updated species list of Tinguá / Mamíferos atuais e extintos na maior Reserva Biológica do Rio de Janeiro: uma lista atualizada de espécies do Tinguá

Abstract: The Tinguá Biological Reserve (TBR) is the largest protected area of this category in Rio de Janeiro state. Here, for the first time, we present the historical composition of terrestrial mammals' assemblage of TBR region. An inventory was conducted using transect surveys, nonstandard transects, survey of museum specimens and informal reports. Considering all the data, eighty-five species were recorded, placing TBR as the second one in the number of mammals recorded in "Serra do Mar" ecoregion of Atlantic Forest and in the Rio de Janeiro state. Among the species with historical records are the jaguar (Panthera onca) and the golden-lion-tamarin (Leontopithecus rosalia) while the current presence of the maned wolf (Chrysocyon brachyurus) was recorded for the first time. Priority studies should focus on Chiroptera, Rodentia and Didelphimorphia orders, especially in the most remote areas of the reserve, and long-term surveys of endangered species. Besides hunting, fragmentation of its interior by roads, pipelines and transmission lines and exotic species, TBR is also threatened by the urban growth around it and the pressure to reduce its area and its protection category, demanding greater attention by the high levels of governance of protected areas in Brazil.

Resumo: A Reserva Biológica Tinguá (RBT) é a maior área protegida desta categoria no estado do Rio de Janeiro. Aqui, pela primeira vez, apresentamos a composição histórica da assembleia de mamíferos terrestres da região da RBT. Um inventário foi realizado utilizando amostragem por transectos, transectos não padronizados, busca por espécimes em museu e relatos. Considerando todos os dados, foram registradas oitenta e cinco espécies, colocando a RBT como a segunda no número de mamíferos registrados na ecorregião "Serra do Mar" da Mata Atlântica e no estado do Rio de Janeiro. Entre as espécies com registros históricos estão a onça-pintada (Panthera onca) e o mico-leão-dourado (Leontopithecus rosalia), enquanto a presença atual do lobo-guará (Chrysocyon brachyurus) foi registrada pela primeira vez. Estudos prioritários devem se concentrar nas ordens de Chiroptera, Rodentia e Didelphimorphia, especialmente nas áreas mais remotas da reserva, e pesquisas de longo prazo sobre espécies ameaçadas de extinção. Além da caça, a fragmentação em seu interior por estradas, gasodutos e linhas de transmissão e a presença de espécies exóticas, a TBR é ameaçada também pelo crescimento urbano no entorno e pela pressão para reduzir sua área e categoria de proteção, exigindo maior atenção dos altos níveis de gestão de áreas protegidas no Brasil.

Credit of ecological interactions: A new conceptual framework to support conservation in a defaunated world.

As defaunation spreads through the world, there is an urgent need for restoring ecological interactions, thus assuring ecosystem processes. Here, we define the new concept of credit of ecological interactions, as the number of interactions that can be restored in a focal area by species colonization or reintroduction. We also define rewiring time, as the time span until all the links that build the credit of ecological interactions of a focal area have become functional again. We expect that the credit will be gradually cashed following refaunation in rates that are proportional to (1) the abundance of the reintroduced species (that is expected to increase in time since release), (2) the abundance of the local species that interact with them, and (3) the traits of reintroduced species. We illustrated this approach using a theoretical model and an empirical case study where the credit of ecological interactions was estimated. This new conceptual framework is useful for setting reintroduction priorities and for evaluating the success of conservation initiatives that aim to restore ecosystem services.

Incorporating animal spatial memory in step selection functions.

Memory is among the most important and neglected forces that shapes animal movement patterns. Research on the movement-memory interface is crucial to understand how animals use spatial learning to navigate across space because memory-based navigation is directly linked to animals' space use and home range behaviour; however, because memory cannot be measured directly, it is difficult to account for. Here, we incorporated spatial memory into step selection functions (SSF) to understand how resource selection and spatial memory affect space use of feral hogs (Sus scrofa). We used Biased Random Bridge kernel estimates linked to residence time as a surrogate for memory and tested four conceptually different dynamic maps of spatial memory. We applied this memory-based SSF to a data set of hog relocations to evaluate the importance of land cover type, time of day and spatial memory on the animals' space use. Our approach has shown how the incorporation of spatial memory into animal movement models can improve estimates of habitat selection. Memory-based SSF provided a feasible way to gain insight into how animals use spatial learning to guide their movement decisions. We found that while hogs selected forested areas and water bodies and avoided grasslands during the day (primarily at noon), they had a strong tendency to select previously visited areas, mainly those held in recent memory. Beyond actively updating their memory with recent experiences, hogs were able to discriminate among spatial memories encoded at different circadian phases of their activity. Even though hogs are thought to have long memory retention, they likely relied on recent experiences because the local food resources are quickly depleted and slowly renewed, yielding an uncertain spatial distribution of resources.

Dealing with extinction is forever: understanding the risks faced by small populations

Despite its importancefor ecology, extinction was often neglected by this science until the present environmental crisis brought the subject to the fore in the early eighties. Important theoretical developments, mainly island biogeography, metapopulation theory and geneticas contributed to build a set of theories on the genetic and ecological processes which threaten the persistence of small populations. Two of the greatest contributions of this paradigm were to show the propabilistic nature of extinction, and to make clear the point how a small population can be extinguished by stochastic processes even if protected from further human intervention. Four such processes can be distinguished: demographic, environmental and genetic stochasticities, and loss of adaptive flexibility. undestanding and modeling these processes resulted in the development of Population viability analysis (PVA), a family of simulation models employed to quantify the future risk of extinction of a small population. The complexity of the extinction processes poses serious problems for the reliability of the predictions; however, PVA has had considerable heuristic value in fostering improvements in understanding extinction. In addition to the scientific and technical aspects, there are also complex economic considerations involved. Nevertheless the small population paradigm and PVA have allowed great advancements in our capacity of devising scientifically sound conservation and management actions to diminish extincion.

Density dependence in within-habitat spatial distribution: contrasting patterns for a rodent and a marsupial in southeastern Brazil

We investigated the relationship between population densities of two species of small mammals and the degree of aggregation in their spatial distributions within a habitat at the Restinga de Barra de Maric , in Rio de Janeiro State. The distribution of the redent Akodon cursor was more clumped at low than at high densities. On the other hand, the aggregation of the marsupial Philander opossum was independent of its abundance. Population density must be included as a variable in quantitative analyses of habitat preferences of those species which, like A. cursor but not P. opossum, show different degrees of habitat selectivity at different population densities.