Nesting Site and Plumage Color Are the Main Traits Associated with Bird Species Presence in Urban Areas

Simple Summary Urban areas are expected to grow in the next decades, filtering bird species from the regional pool based on their life history traits. The objective of this study is to determine different bird species responses to urbanization using ordination analysis, and to characterize their life history traits combining information about diet, habitat and plumage color. Species identified as 'urban exploiters' tended to nest in buildings and with uniform plumage, whereas those identified as 'urban avoiders' tended to be ground nesting species with variable plumage. A third type, 'urban adapters', tended to be tree-nesting species with a low diet breadth, intermediate plumage lightness, low presence of plumage sexual dimorphism and high presence of iridescence. The results suggest that nest predation and habitat loss may exclude ground nesting birds from urban areas. The high density of pedestrians in urban centers may favor uniform plumages in birds that enhance camouflage. Urban areas are expected to grow in the next decades, filtering bird species from the regional pool based on their life history traits. Although the impact of urbanization on traits such as diet, habitat and migratory behavior has been analyzed, their joint role with other traits related to plumage color has not yet been analyzed. Urban characteristics such as impervious surfaces, human presence and pollutants may be related to dark and uniform plumages. The objective of this study is to determine different bird species responses to urbanization using ordination analysis, and to characterize their life history traits combining information about diet, habitat and plumage color. Birds were surveyed along urban-rural gradients located in three cities of central Argentina. Species associations with urban characteristics were assessed through principal component analysis. Two axes were obtained: the first related positively to urban exploiters and negatively to urban avoiders, and a second axis related negatively to urban adapters. The scores of each axis were related to species traits through phylogenetic generalized least squares models. Species identified as 'urban exploiters' tended to nest in buildings and have uniform plumage, whereas those identified as 'urban avoiders' tended to be ground-nesting species with variable plumage. A third type, 'urban adapters', tended to be tree-nesting species with a low diet breadth, intermediate plumage lightness, low presence of plumage sexual dimorphism and high presence of iridescence. The results suggest that nest predation and habitat loss may exclude ground nesting birds from urban areas. The high density of pedestrians and domestic animals, such as cats and dogs, in urban centers may favor uniform plumages in birds that enhance camouflage.

Automated summary

This study aimed to determine the responses of different bird species to urbanization using ordination analysis and to describe their life history traits by combining information on diet, habitat, and plumage color. The results showed that certain bird species, termed "urban exploiters," tend to nest in buildings and have uniform plumage, while others, termed "urban avoiders," tend to be ground-nesting species with variable plumage. A third type, called "urban adapters," tend to be tree-nesting species with specific traits such as a low diet breadth, intermediate plumage lightness, low presence of sexual dimorphism, and high presence of iridescence. This study suggests that nest predation and habitat loss may lead to exclusion of ground nesting birds from urban areas, and the high density of pedestrians and domestic animals in urban centers may favor uniform plumages in birds to enhance camouflage.