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Many vertebrate species undergo population fluctuations that may be random or regularly cyclic in nature. Vertebrate population cycles in northern latitudes are driven by both endogenous and exogenous factors. Suggested causes of mysterious disappearances documented for populations of the Neotropical, herd-forming, white-lipped peccary (Tayassu pecari, henceforth "WLP") include large-scale movements, overhunting, extreme floods, or disease outbreaks. By analyzing 43 disappearance events across the Neotropics and 88 years of commercial and subsistence harvest data for the Amazon, we show that WLP disappearances are widespread and occur regularly and at large spatiotemporal scales throughout the species' range. We present evidence that the disappearances represent 7-12-year troughs in 20-30-year WLP population cycles occurring synchronously at regional and perhaps continent-wide spatial scales as large as 10,000-5 million km2. This may represent the first documented case of natural population cyclicity in a Neotropical mammal. Because WLP populations often increase dramatically prior to a disappearance, we posit that their population cycles result from over-compensatory, density-dependent mortality. Our data also suggest that the increase phase of a WLP cycle is partly dependent on recolonization from proximal, unfragmented and undisturbed forests. This highlights the importance of very large, continuous natural areas that enable source-sink population dynamics and ensure re-colonization and local population persistence in time and space.

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Mitigating the massive impacts of defaunation on natural ecosystems requires understanding and predicting hunting effort across the landscape. But such understanding has been hindered by the difficulty of assessing the movement patterns of hunters in thick forests and across complex terrain. We statistically tested hypotheses about the spatial distribution of hunting with circuit theory and structural equation models. We used a data set of >7000 known kill locations in Guyana and hunter movement models to test these methods. Comparing models with different resistance layers (i.e., different estimates of how terrain and land cover influence human movement speed) showed that rivers, on average, limited movement rather than serving as transport arteries. Moreover, far more kills occurred close to villages than in remote areas. This, combined with the lack of support for structural equation models that included latent terms for prey depletion driven by past overhunting, suggests that kill locations in this system tended to be driven by where hunters were currently foraging rather than by influences of historical harvest. These analyses are generalizable to a variety of ecosystems, species, and data types, providing a powerful way of enhancing maps and predictions of hunting effort across complex landscapes.

Comprensión de la Distribución de los Esfuerzos por Obtener Carne de Caza a lo largo de un Paisaje Mediante la Comprobación de Hipótesis sobre el Forrajeo Humano Resumen La mitigación de los impactos masivos de la defaunación sobre los ecosistemas naturales requiere de comprensión y predicción de los esfuerzos de caza a lo largo del paisaje. Dicha comprensión se ha visto obstaculizada por la dificultad que representa la evaluación de los patrones de movimiento de los cazadores en bosques densos y a través de un terreno complejo. Analizamos estadísticamente las hipótesis sobre la distribución espacial de la cacería mediante una teoría de circuito y modelos de ecuaciones estructurales. Usamos un conjunto de datos de más de 7000 localidades conocidas de sacrificios en Guayana y los modelos de movimiento de los cazadores para probar estos modelos. La comparación entre modelos con diferentes capas de resistencia (es decir, diferentes estimaciones de cómo el terreno y la cobertura de suelo influyen sobre la velocidad del movimiento humano) mostró que los ríos, en promedio, limitaron el movimiento en lugar de funcionar como arterias de transporte. Además, ocurrieron mucho más sacrificios cerca de las aldeas que en las áreas remotas. Lo anterior, combinado con la falta de apoyo para los modelos de ecuaciones estructurales que incluyeron los términos latentes para la reducción de presas causada por la sobrecaza pasada, sugiere que las localidades de sacrificios en este sistema tendieron a ser seleccionadas por la ubicación actual en la que los cazadores se encontraban forrajeando y no por la influencia de la cosecha histórica. Estos análisis son generalizables para una variedad de ecosistemas, especies y tipos de datos, lo que proporciona una manera poderosa de mejorar los mapas y las predicciones de los esfuerzos de cacería a través de paisajes complejos.

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Biodiversity affects many ecosystem functions and services, including carbon cycling and retention. While it is known that the efficiency of carbon capture and biomass production by ecological communities increases with species diversity, the role of vertebrate animals in the carbon cycle remains undocumented. Here, we use an extensive dataset collected in a high-diversity Amazonian system to parse out the relationship between animal and plant species richness, feeding interactions, tree biomass and carbon concentrations in soil. Mammal and tree species richness is positively related to tree biomass and carbon concentration in soil-and the relationship is mediated by organic remains produced by vertebrate feeding events. Our research advances knowledge of the links between biodiversity and carbon cycling and storage, supporting the view that whole community complexity-including vertebrate richness and trophic interactions-drives ecosystem function in tropical systems. Securing animal and plant diversity while protecting landscape integrity will contribute to soil nutrient content and carbon retention in the biosphere.

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The development of species distribution models (SDMs) can help conservation efforts by generating potential distributions and identifying areas of high environmental suitability for protection. Our study presents a distribution and habitat map for lowland tapir in South America. We also describe the potential habitat suitability of various geographical regions and habitat loss, inside and outside of protected areas network. Two different SDM approaches, MAXENT and ENFA, produced relative different Habitat Suitability Maps for the lowland tapir. While MAXENT was efficient at identifying areas as suitable or unsuitable, it was less efficient (when compared to the results by ENFA) at identifying the gradient of habitat suitability. MAXENT is a more multifaceted technique that establishes more complex relationships between dependent and independent variables. Our results demonstrate that for at least one species, the lowland tapir, the use of a simple consensual approach (average of ENFA and MAXENT models outputs) better reflected its current distribution patterns. The Brazilian ecoregions have the highest habitat loss for the tapir. Cerrado and Atlantic Forest account for nearly half (48.19%) of the total area lost. The Amazon region contains the largest area under protection, and the most extensive remaining habitat for the tapir, but also showed high levels of habitat loss outside protected areas, which increases the importance of support for proper management.