Disappearance of an ecosystem engineer, the white-lipped peccary (Tayassu pecari), leads to density compensation and ecological release.

Given the rate of biodiversity loss, there is an urgent need to understand community-level responses to extirpation events, with two prevailing hypotheses. On one hand, the loss of an apex predator leads to an increase in primary prey species, triggering a trophic cascade of other changes within the community, while density compensation and ecological release can occur because of reduced competition for resources and absence of direct aggression. White-lipped peccary (Tayassu pecari-WLP), a species that typically co-occurs with collared peccary (Pecari tajacu), undergo major population crashes-often taking 20 to 30-years for populations to recover. Using a temporally replicated camera trapping dataset, in both a pre- and post- WLP crash, we explore how WLP disappearance alters the structure of a Neotropical vertebrate community with findings indicative of density compensation. White-lipped peccary were the most frequently detected terrestrial mammal in the 2006-2007 pre-population crash period but were undetected during the 2019 post-crash survey. Panthera onca (jaguar) camera trap encounter rates declined by 63% following the WLP crash, while collared peccary, puma (Puma concolor), red-brocket deer (Mazama americana) and short-eared dog (Atelocynus microtis) all displayed greater encounter rates (490%, 150%, 280%, and 500% respectively), and increased in rank-abundance. Absence of WLP was correlated with ecological release changes in habitat-use for six species, with the greatest increase in use in the preferred floodplain habitat of the WLP. Surprisingly, community-weighted mean trait distributions (body size, feeding guild and nocturnality) did not change, suggesting functional redundancy in diverse tropical mammal assemblages.

Human disturbance and shifts in vertebrate community composition in a biodiversity hotspot.

Understanding how human modification of the landscape shapes vertebrate community composition is vital to understanding the current status and future trajectory of wildlife. Using a participatory approach, we deployed the largest camera-trap network in Mesoamerica to date to investigate how anthropogenic disturbance shapes the occupancy and co-occurrence of terrestrial vertebrate species in a tropical biodiversity hotspot: the Osa Peninsula, Costa Rica. We estimated species richness in different categories of land protection with rarefaction analysis and estimated the expected occupancy with a joint species distribution model that included covariates for anthropogenic disturbance, land protection, habitat quality, and habitat availability. Areas with the most stringent land-use protections (e.g., Corcovado National Park, 24 species [95% CI 23-25]) harbored significantly more species than unprotected areas (20 species [19.7-20.3]), mainly due to a reduced presence of large-bodied species of conservation concern in unprotected areas (e.g., jaguar Panthera onca and white-lipped peccary Tayassu pecari). Small-bodied generalist species, such as opossums (Didelphidae) and armadillos (Dasypus novemcinctus), in contrast, were more common at disturbed sites, resulting in a significant difference in vertebrate community composition between sites with low and high disturbance. Co-occurrence of species was also mainly associated with response to disturbance. Similar responses to disturbance create two groups of species, those whose site-level occupancy usually increased as anthropogenic disturbance increased and those whose estimated occupancy decreased. The absence of large-bodied species entails an important loss of ecological function in disturbed areas and can hinder forest development and maintenance. Efforts to protect and restore forested landscapes are likely having a positive effect on the abundance of some threatened species. These efforts, however, must be sustained and expanded to increase connectivity and ensure the long-term viability of the wildlife community.

Perturbaciones Humanas y Cambios en la Composición de la Comunidad de Vertebrados en un Punto Caliente de Biodiversidad Resumen El entendimiento de cómo las modificaciones humanas del paisaje conforman la composición de las comunidades de vertebrados es vital para entender el estado actual y la trayectoria futura de la fauna. Mediante una estrategia participativa, desplegamos la mayor red de cámaras trampa en Mesoamérica hasta la fecha para investigar cómo la perturbación antropogénica determina la ocupación y coocurrencia de las especies terrestres de vertebrados en un punto caliente de biodiversidad tropical: la Península de Osa, Costa Rica. Estimamos la riqueza de especies en diferentes categorías de protección de suelo con un análisis de rarefacción y estimamos la ocupación esperada con un modelo de distribución conjunta de especies que incluyó covariables para la perturbación antropogénica, la protección del suelo, la calidad del hábitat y la disponibilidad del hábitat. Las áreas con la protección más estricta de uso de suelo (p. ej.: Parque Nacional Corcovado, 24 especies [95% CI 23-25]) albergaron significativamente a más especies que las áreas desprotegidas (20 especies [19.7-20.3]), principalmente debido a la presencia reducida de especies de talla grande de interés para la conservación en las áreas desprotegidas (p. ej.: el jaguar Panthera onca, el pecarí de labios blancos, Tayassu pecari). Al contrario, las especies generalistas de talla pequeña, como las zarigüeyas (Didelphidae) y el armadillo (Dasypus novemcinctus) fueron más comunes en los sitios perturbados, lo que resulta en una diferencia significativa en la composición de las comunidades de vertebrados entre los sitios con una perturbación baja y alta. La coocurrencia de especies también estuvo asociada principalmente con la respuesta a la perturbación. Las respuestas similares a la perturbación crean dos grupos de especies: aquellas cuya ocupación a nivel de sitio generalmente incrementó conforme incrementó la perturbación antropogénica y aquellas cuya ocupación estimada disminuyó. La ausencia de especies de talla grande conlleva una pérdida importante de la función ecológica en las áreas perturbadas y puede dificultar el desarrollo y mantenimiento del bosque. Los esfuerzos para proteger y restaurar los paisajes forestales probablemente estén teniendo un efecto positivo sobre la abundancia de algunas especies amenazadas. Estos esfuerzos, sin embargo, deben ser sostenidos y expandidos para incrementar la conectividad y asegurar la viabilidad a largo plazo de la comunidad faunística.

Spider Monkeys Rule the Roost: Ateline Sleeping Sites Influence Rainforest Heterogeneity.

: The sleeping site behavior of Ateline primates has been of interest since the 1980s, yet limited focus has been given to their influence upon other rainforest species. Here, we use a combination of arboreal and terrestrial camera traps, and dung beetle pitfall traps, to characterize spider monkey sleeping site use and quantify the impact of their associated latrines on terrestrial vertebrate and dung beetle activity. We also characterize the physical characteristics of the sleeping sites and the floristic and soil composition of latrines beneath them. Spider monkey activity at sleeping sites peaked at dawn and dusk and group composition varied by sex of the adults detected. The habitat-use of terrestrial fauna (vertebrates and dung beetles) differed between latrine sites and non-latrine controls, underpinned by species-specific changes in the relative abundance of several seed-dispersing species (such as paca and great curassow). Seedling density was higher in latrines than in non-latrine controls. Although most soil properties were similar between latrines and controls, potassium and manganese concentrations were different. These results suggest that spider monkey sleeping site fidelity leads to a hotspot of ecological activity in latrines and downstream impacts on rainforest floristic composition and diversity.