Landbird Assemblages in Different Agricultural Landscapes: A Case Study in the Pampas of Central Argentina

Abstract

Abstract. A combination of elements (e.g., crops and pasture lands, strips of roadside vegetation, woodlots, temporary wetlands) increases the heterogeneity of rural landscapes. Agricultural landscapes range from homogeneous, dominated by a single element (i.e., pure cropland or pure pastoral farming) to heterogeneous, dominated by two or more elements (i.e., mixed farming). In this study we characterized landbird assemblages in various agricultural landscapes (cropland, pastoral, and mixed landscapes) in the Pampas of central Argentina, surveying along transects to quantify species richness, composition, and abundance. Mixed landscapes were more heterogeneous than pastoral areas and cropland. Species richness, particularly of generalists, was greater in mixed landscapes. Richness of grassland specialists (species of increased conservation concern in the Pampas) was lower in croplands than in pastoral and mixed landscapes. An indicator-species analysis supported the association of some grassland specialists (Rhea americana, Asthenes hudsoni, Embernagra platensis, Pseudoleistes virescens) with pastoral landscapes. Our results suggest that maintaining landscape heterogeneity throughout the Pampas (i.e., mixed landscapes) is important for preserving species richness of birds. But several threatened grassland specialists inhabiting the Pampas, such as Rhea americana and Asthenes hudsoni, are found exclusively in pastoral landscapes, so the long-term survival of these species will depend on the conservation of this landscape type.Key words: agroecosystem, grassland bird species, land use, matrix, Neotropical Region. Ensambles de Aves Terrestres en Diferentes Paisajes Rurales: Un Estudio de Caso en las Pampas del Centro de ArgentinaResumen. La combinación de elementos del paisaje (e.g., cultivos, pastizales, vegetación de bordes de caminos, arboledas y humedales temporarios) incrementa la heterogeneidad y define diferentes tipos de paisajes rurales, desde paisajes homogéneos dominados por un único elemento (i.e., paisaje de cultivo o ganadero) hasta paisajes heterogéneos dominados por dos o más elementos (i.e., paisajes mixtos). En este estudio caracterizamos los ensambles de aves terrestres en diferentes tipos de paisajes rurales de la Pampa argentina (paisajes de cultivos, ganaderos y mixtos). Las aves terrestres fueron muestreadas con transectas para determinar la riqueza de especies, la composición y la abundancia en cada tipo de paisaje rural. El paisaje mixto tuvo una mayor heterogeneidad que los paisajes de cultivos y ganaderos. El paisaje mixto tuvo una mayor riqueza de especies que los paisajes de cultivos y ganaderos, en especial de especies generalistas. Por otro lado, el paisaje de cultivos tuvo la menor riqueza de especialistas de pastizal (aquellas con problemas de conservación en la Pampa) que los paisajes ganaderos y mixtos. Un análisis de especies indicadoras destacó la asociación entre algunas especies de pastizal (Rhea americana, Asthenes hudsoni, Embernagra platensis, Pseudoleistes virescens) y el ...

Burrowing activity by armadillos in agroecosystems of central Argentina: Biogeography, land use, and rainfall effects

“…Thus, the matrix of scarce cropland and abundant natural or semi-natural grasslands seem to favor D. hybridus (Abba et al, 2007;Abba and Vizcaíno, 2011). Similar responses of vertebrates to dominant landscape matrix in the study area have also been reported for small mammals and birds (Codesido et al, 2013).…”

“…The effects of this recent agriculturization on biodiversity has already been detected in both birds (Codesido et al, 2008(Codesido et al, , 2013Filloy and Bellocq, 2007;Weyland et al, 2014) and small mammal assemblages at landscape and regional scales González-Fischer et al, 2011. Additionally, effect of land use on armadillos has been observed at a local scale in a livestock area of the Flooding Pampas, where D. hybridus was associated with natural grasslands and avoided cultivated pastures (Abba et al, 2007).…”

Birds of a wildlife reserve in the South American Pampa (Córdoba, Argentina)

“…The species recorded in DHWR showed a high specificity in the use of habitat which is consistent with a close relationship between bird species and structural and floristic characteristics of the vegetation (Graham and Blake 2001;Naugle et al 2001;Skowno and Bond 2003;Wakeley et al 2007;Di Giacomo and Lopez De Casenave 2010). This suggests that increasing complexity in habitat structure (horizontal, vertical and qualitative variation of elements present) generates greater resources for birds, allowing the persistence of a greater number of species and guilds than in less complex habitats (MacArthur and MacArthur 1961;Tews et al 2004;Codesido et al 2013).…”

What land use better preserves taxonomic and functional diversity of birds in a grassland biome?

“…Also, moderate grazing rates may provide grass coverage and height similar to those of natural grasslands, as found in the rangelands of North America (Peterjohn 2003). Furthermore, pastures may offer horizontal and vertical structural diversity for birds nesting on the ground, such as the Burrowing Owl (Athene cunicularia; Pairo et al 2017), or on grasses, such as the Great Pampa-Finch (Embernagra platensis), the Brown-and-yellow Marshbird (Pseudoleistes virescens), the Hudson's Canastero (Asthenes hudsoni), and the Greater Rhea (Rhea americana; Codesido et al 2013). Also, grazing management could be used in the restoration of seminatural grasslands (WallisDeVries et al 1998).…”