THE AVIFAUNA OF THE RÍO TIGRE BASIN, NORTHERN PERÚ

ABSTRACT ∙ The Tigre river basin in the Amazonian lowlands of northern Perú harbors a hyperdiverse avifauna that remains under‐surveyed and poorly known. We conducted the first comprehensive ornithological inventory of the basin. Observational fieldwork at 42 sites spread across the Peruvian portion of the basin resulted in a bird list of 584 species, reflecting several noteworthy patterns in the avian biogeography of northern Perú. These patterns include the distribution of several species that specialize on nutrient‐poor habitats, such as weathered clay terraces and peatlands. Peatland forests are especially poorly studied in Perú and represent a novel habitat association for these species. We also report on the presence of a suite of species with primarily montane distributions that occur in low density across the Amazonian lowlands and in the study area. Current conservation challenges in the Tigre basin include deforestation and pollution associated with hydrocarbons extraction and infrastructure projects.RESUMEN ∙ Avifauna de la cuenca del río Tigre, Perú La cuenca del río Tigre en las tierras bajas del norte de la Amazonía peruana tiene una avifauna súper diversa que sin embargo es muy poco conocida. Realizamos el primer inventario ornitológico de la cuenca. Observaciones de aves en 42 sitios resultaron en una lista de 584 especies de aves registradas en la zona de estudio. Un grupo particular de esta comunidad de aves son aquellas que se distribuyen en los bosques arcillosos pobres a lo largo del río Pucacuro y sobre bosques de turberas en el bajo río Tigre. Reportamos especies generalmente consideradas como especies facultativas u obligadas de hábitats de suelos de arena blanca en la zona de estudio. Los bosques sobre turberas aún se encuentran muy poco estudiados por los ornitólogos y representan un nuevo espacio para las especies que por lo general encontramos sobre los bosques de arena blanca. Adicionalmente reportamos un grupo de especies que generalmente son comunes en el pie de monte andino, pero que ocurren en bajas densidades en el área de estudio. Las amenazas actuales a la conservación de la zona incluyen la deforestación y la contaminación asociada con actividades petroleras y proyectos de infraestructura

Understanding different dominance patterns in western Amazonian forests

Dominance of neotropical tree communities by a few species is widely documented, but dominant trees show a variety of distributional patterns still poorly understood. Here, we used 503 forest inventory plots (93,719 individuals ≥2.5 cm diameter, 2609 species) to explore the relationships between local abundance, regional frequency and spatial aggregation of dominant species in four main habitat types in western Amazonia. Although the abundance-occupancy relationship is positive for the full dataset, we found that among dominant Amazonian tree species, there is a strong negative relationship between local abundance and regional frequency and/or spatial aggregation across habitat types. Our findings suggest an ecological trade-off whereby dominant species can be locally abundant (local dominants) or regionally widespread (widespread dominants), but rarely both (oligarchs). Given the importance of dominant species as drivers of diversity and ecosystem functioning, unravelling different dominance patterns is a research priority to direct conservation efforts in Amazonian forests.Publisher PDFPeer reviewe

How should beta-diversity inform biodiversity conservation?

To design robust protected area networks, accurately measure species losses, or understand the processes that maintain species diversity, conservation science must consider the organization of biodiversity in space. Central is beta-diversity - the component of regional diversity that accumulates from compositional differences between local species assemblages. We review how beta-diversity is impacted by human activities, including farming, selective logging, urbanization, species invasions, overhunting, and climate change. Beta-diversity increases, decreases, or remains unchanged by these impacts, depending on the balance of processes that cause species composition to become more different (biotic heterogenization) or more similar (biotic homogenization) between sites. While maintaining high beta-diversity is not always a desirable conservation outcome, understanding beta-diversity is essential for protecting regional diversity and can directly assist conservation planning. Beta-diversity reveals the spatial scaling of diversity loss.Beta-diversity illuminates mechanisms of regional diversity maintenance.Human activities cause beta-diversity to increase, decrease, or remain unchanged.Conservation significance of beta-diversity shift depends on local diversity dynamics

Tree survey data

Data from tree surveys near Iquitos, Peru (one row per stem

ReadME

Descriptions of data file

River island birds (Rosenberg)

Commonness of bird species on river islands, based on Rosenberg (1990

Bird survey data

Collected and identified by Jacob B. Socolar. Please consider offering co-authorship on any publication that makes extensive use of these data

R script for analysis

Performs the analyses described in Socolar et al 2019 (Conservation Biology

Census Points

Point-level covariate