Bird-habitat associations in coastal rangelands of southern Brazil

Abstract

ABSTRACT. Nearly all remnants of temperate grasslands in southeastern South America are used for livestock ranching and are subject to habitat degradation resulting from this activity. Exploring how habitat features affect the composition of grassland avifaunal communities is a first step to understand how current cattle-ranching management practices impact avian diversity. We used canonical ordination to test for relationships between five habitat variables and the composition of the bird community in coastal grasslands in southern Brazil. We sampled pastures with different heights, from overgrazed short-grass to tall herbaceous vegetation. We recorded 1,535 individuals and 27 species of birds. The first ordination axis indicated a strong contribution of mean vegetation height on the composition of the bird community, whereas the second axis revealed the influence of herbaceous vegetation patchiness and woody vegetation cover. Three groups of species were revealed by the ordination: one more diffuse associated with intermediate and tall herbaceous vegetation, another with short grass, and a third with vegetation patchiness and woody vegetation. Species restricted to tall herbaceous vegetation are negatively impacted from habitat degradation resulting from overgrazing and trampling by livestock, and mowing and burning of tall plants. Occurrence of these species in our study area is related with the presence of swales immediately behind the dune system and where remnants of tall vegetation persist. Birds of pastures with ample cover of short herbaceous plants, including one globally threatened species and six other restricted to short-grass habitat, apparently benefit from local livestock management practices. Woody vegetation possibly functions as a keystone structure, enabling the occurrence in grasslands of avian species that rely on shrubby habitat. Although livestock ranching promotes the diversity of habitats by creating distinct patches of vegetation height in grasslands, current management practices directed to the maintenance of short grass pastures may eliminate an entire subset of species, including regionally threatened taxa, and reduce avian diversity. The maintenance of large patches of tall herbaceous plants is needed to ensure the survival of species reliant on this type of grassland structure in our study area. KEYWORDS.Habitat use, livestock ranching, grassland management, canonical ordination, "Campos" grasslands.RESUMO. Associações entre aves e variáveis de habitat em campos costeiros do sul do Brasil. Praticamente todos os remanescentes de campo temperado no sudeste da América do Sul são usados para a pecuária e estão sujeitos à degradação de habitat resultante dessa atividade. Explorar como a composição das comunidades de aves é influenciada por características de habitat é um passo inicial para compreender o impacto que as atuais práticas de manejo da pecuária em campos nativos exercem sobre a biodiversidade. Nós usamos ordenação canônica para testar as relações entre cinco variáveis de hab...

Success of active restoration in grasslands: a case study of birds in southern Brazil

“…The greater height in AR resulted from the conspicuous presence of shrubs and Baccharis spp. ; this woody vegetation in grasslands provides resources for birds, increasing diversity (Dias et al ). Regarding the time of restoration, in the second year of active restoration the grassland bird species richness and composition resembled the reference area, whereas we had initially hypothesized that this would occur only in the third year.…”

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Passive restoration contributes to bird conservation in Brazilian Pampa grasslands

“…One factor likely contributing to this difference was the difference between the two grassland types in vegetation height, a variable that influenced the occurrence of three species. The results of some studies suggest that vegetation height is an important predictor of the occurrence of grassland birds, in addition to the amount of bare ground and litter depth (Fisher and Davis , Dias et al ). In our study, Blue‐black Grassquits and Chestnut Seedeaters were only observed in PR and Wedge‐tailed Grass‐Finches were more abundant in PR, the grassland type with taller vegetation and greater coverage of tall grass.…”

“…data). Eryngium and Baccharis are native plants, woody vegetation ( Baccharis) provides important resources for birds (Dias et al ), and some birds use Eryngium as a perch site (Dias et al ). To obtain a mean value for vegetation variables at the point‐count level, we calculated the mean for each of the five quadrats per point count.…”

Dynamic multi-species occupancy models of birds of high-altitude grasslands in eastern South Africa

“…We assumed mham walking ramher mhan poinm counms would maximize demecmion of mhreamened (Taylor, Peacock & Wanless, 2015) and secremive grassland birds such as Yellow-breasmed Pipim (Anthus Chloris). Each birds was recorded once am mhe firsm sighming or when firsm heard (Dias, Basmazini & Gianuca, 2014) and were assumed mo be inside mhe ploms limims. The sighming and recording of birds was done by one person wimh good experience of habimams of birds of mhis region.…”