The role of grazing management practices and tussock-forming plants on grassland birds in the Argentine Pampas

Abstract

The structure of vegetation significantly impacts grassland birds. In temperate Southeastern South America (SESA), different cattle grazing practices shape grassland vegetation structure, influencing bird abundance and richness. We studied SESA grassland birds and vegetation structure in semi-natural grasslands on ten ranches located in the Flooding Pampas of Argentina, which implemented two different kinds of practices: continuous grazing management (CGM, traditional management) and ecological process-based management (EPM). Generalized linear mixed modelsrevealed that grassland bird abundance was higher under EPM than under CGM. When grouping birds by grassland habitat use, broad bird species, that use both short and tall grass, responded to management depending on the presence or absence of tussock-forming plants. Short-grass and tall-grass species abundances did not respond directly to management, but tall-grass species responded to the presence of tussock-forming plants. Canonical correspondence analysis (CCA) further showed strong associations between grassland bird species groups and vegetationstructure, providing further insight into species of particular conservation concern such as the Bay-capped Wren-spinetail (Spartonoica maluroides)—associated with tall grasslands with tussocks- and the Buff-breasted Sandpiper (Calidris subruficollis)—associated with short, homogeneous grasslands. Our results show that grassland height, vegetation structure heterogeneity and the presence of tussock-forming plant species are the main factors influencing grassland birds. Management practices also affect how some broad bird species respond to vegetation structure, particularly in the absence of tussocks. This study contributes to better understanding how grazingmanagement practices (as well as the preservation of tussock-forming plants) can help conserve many SESA grassland bird species.