From Wiens to Robel: A Review of Grassland‐Bird Habitat Selection

Abstract

Efforts to stabilize or increase grassland bird populations require identification of suitable habitat as a first step. Although the number of studies examining grassland‐bird habitat selection has increased substantially in recent years, much uncertainty exists regarding local‐scale habitat variables that researchers should consider. We reviewed 57 studies and identified important vegetation features correlated with grassland bird abundance, density, occurrence, and nest and territory selection. Our objectives were to 1) guide future studies of grassland‐bird habitat use by providing a reduced set of relevant vegetation characteristics, 2) challenge researchers to critically think about what variables to consider, and 3) highlight the need to include consistent definitions of terms used to describe grassland bird habitat. We identified 9 variables that were important predictors of habitat use by grassland birds: coverage of bare ground (important in 50% of the instances where it was included), grass (34% of instances), dead vegetation (33% of instances), forbs (31% of instances), and litter (29% of instances), along with an index of vegetation density (39% of instances) and volume (39% of instances), litter depth (36% of instances), and vegetation height (41% of instances). Only 25% of studies provided information on effects sizes and measures of variance. Furthermore, definitions of measured habitat variables were not consistent among studies. We provide definitions of the 9 important variables and implore authors to report effect size and measures of variance. Standardization of terms and reporting of meaningful results will facilitate replication of wildlife research and enhance our ability to recognize general patterns that emerge from observational studies of habitat use.

Bird-habitat associations in coastal rangelands of southern Brazil

“…Habitat loss and degradation has been particularly severe in temperate grasslands, with grassland birds experiencing expressive populational declines in recent decades (Vickery & Herkert, 2001;FisHer & DaVis, 2010). Expansion of agriculture, afforestation and urbanization are the main causes of habitat loss, whereas overgrazing and trampling by livestock and inadequate burning regimes are the main drivers of habitat degradation (HenwooD, 2010;azpiroz et al, 2012).…”

“…The plight of grassland birds has spawned a series of investigations addressing grassland-bird habitat relationships (see FisHer & DaVis, 2010). One of the main conclusions of these studies is that the abundance and distribution of species, and the composition of avian communities in grasslands, are largely determined by variations in specific habitat features (Vickery & Herkert, 2001;Derner et al, 2009;FisHer & DaVis, 2010;azpiroz et al, 2012).…”

“…One of the main conclusions of these studies is that the abundance and distribution of species, and the composition of avian communities in grasslands, are largely determined by variations in specific habitat features (Vickery & Herkert, 2001;Derner et al, 2009;FisHer & DaVis, 2010;azpiroz et al, 2012). The heterogeneity of the vegetation and Iheringia, Série Zoologia, Porto Alegre, 104(2):200-208, 30 de junho de 2014 the presence of "keystone structures" -distinct spatial structures that provide resources, shelter, or goods and services crucial for other species -are the main habitat features that influence the diversity and composition of avifaunal communities in grasslands (tews et al, 2004;FisHer & DaVis, 2010). These variables are mediated by complex interactions between "ecosystem engineers" such as grazers and burrowers, and fire and drought regimes (ceballos et al, 1999;FuHlenDorF et al, 2009;allreD et al, 2011).…”

“…Most studies focusing on grassland-bird habitat relationships have been conducted in North America and Europe (FisHer & DaVis, 2010;bálDi & batáry, 2011). In southeastern South America, where temperate grasslands once covered 762,000 km 2 in southern Paraguay and Brazil, Uruguay, and eastern Argentina, the majority of studies addressing this issue have been conducted in the Argentine Pampas unit (azpiroz et al, 2012).…”

“…Habitat identification, management and restoration, and knowledge of grassland-bird habitat use and selection, are key aspects to stabilize or increase grassland bird populations (FisHer & DaVis, 2010). Thus, exploring the influence of habitat features on the composition of bird communities in the Campos grasslands of southern Brazil is a first step towards a better understanding of how habitat variables affect groups of species in a similar way.…”