Landbird assemblages in temperate agroecosystems: analyses at plot and landscape scales

Abstract

Agroecosystems consist of an agricultural matrix composed of plots under crop and livestock use, along with several elements that provide habitat diversity to the rural landscape. Avian species may respond to the presence of those characteristics at both landscape and local scales. We compared species richness between land-bird assemblages from two previous studies carried out during the breeding season in temperate agroecosystems of Argentina at plot scale (local; n=23 sites) through samplings within plots, and at landscape scale (n=30 sites) through samplings along secondary roads, which can include plots, plot margins, roadsides, railways, woodlots and farmsteads. We standardized 100 min of observation for each sample in order to compare both studies. We recorded 60 species at plot scale and 72 species at landscape scale. Species accumulation curves indicated greater species richness at the landscape scale, which included some generalists that nest in exotic trees, shrubs and farmsteads. In addition, we found a higher relative abundance of species associated with open habitats at the plot scale, such as Correndera Pipit Anthus correndera and Short-billed Pipit Anthus furcatus which nest on the ground, whereas at the landscape scale we found a greater relative abundance of species nesting in shrubby and woody vegetation, such as Double-collared Seedeater Sporophila caerulescens and Rufous Hornero Furnarius rufus. Our results highlight the role of spatial scale in the analysis of landbird assemblages in agroecosystems, showing that species richness is higher at landscape than at plot scale.