Threatened birds, dynamic habitats and disturbance processes – conservation biology in one of the worlds most understudied savanna ecosystems

Abstract

The Beni savannas of Northern Bolivia are one of the world’s most remote, understudied and threatened grassland ecosystems. Here, vegetation dynamics are driven by complex interacting environmental and agricultural disturbance processes, including flooding, fire and cattle grazing. In turn, the distribution of bird communities is shaped by how these processes influence prevailing vegetation composition and structure. We explore how the distribution and habitat use of avian grassland specialists is influenced by habitat structure and disturbance history along the cerrado-grassland gradient with focus on three key conservation species, Alectrurus tricolor (cock-tailed tyrant), Coryphaspiza melanotis (black-masked finch, and Emberizoides herbicola (wedge-tailed grass-finch). Our results indicate that: i) Cock-tailed tyrants specialize on specific disturbance-sensitive micro-habitats within the cerrado-grassland ecotone, while black-masked finch and wedge-tailed grass-finch are generalists but track available food resources that may be influenced by the timing and severity of disturbance processes; ii) Black-masked finch and cock-tailed tyrants have greater sensitivity to grazing pressure and agricultural fire-management than the more common wedge-tailed grass-finch – a factor likely contributing to their current high rates of global decline; iii) Prescribed burning is integral for the conservation of avian communities within this region, but scale, timing and frequency are likely important considerations due to their influence on key habitat resources; and iv) Management within protected areas that aims to retain a range of post-burn stages in a shifting mosaic could help to support wider avian communities. Our study develops a better understanding of how disturbance processes influence biodiversity in this understudied region. Our results will be critical for strengthening management protocols in protected areas like the Barba Azul Nature Reserve, and will help inform more sustainable approaches to agriculture in the wider Beni Savanna region.