Wintering Town: Individual Quality of Migratory Warblers Using Green Urban Areas in a Neotropical City

A. Karen Ortiz-Asbun,Jorge E. Schondube,Rodrigo Pacheco-Muñoz,Adrián Ceja-Madrigal,Edgar Pérez-Negrón

doi:10.3389/fevo.2021.779507

A. Karen Ortiz-Asbun, Jorge E. Schondube

Open Access

https://doi.org/10.3389/fevo.2021.779507

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Abstract

Migratory birds can be familiar winter visitors of Neotropical cities. However, of the regional migrant species bird pool, only a few species are abundant in urban areas. Their presence inside cities has been positively related to green urban areas with high tree cover. However, urban elements like artificial lights can also attract them to cities. Habitat quality that enables energetic refueling for migrant birds is crucial in all their annual migratory stages. While some Nearctic cities offer a high-quality refueling habitat for migrant birds, we lack this information for Neotropical cities where migratory birds winter. In this study, we evaluate whether the urban green areas of a Neotropical city act as high-quality habitats for two abundant species of migratory warblers: Setophaga coronata and Leiothlypis ruficapilla. We assessed this by capturing birds inside three urban green areas and comparing their abundances, population structure, and individual quality (scaled-mass index—SMI) with individuals spending winter in natural vegetation habitats outside the city. We found that both species do not show differences in SMI between urban and non-urban sites. We also found that Setophaga coronata had a higher capture rate in urban than non-urban sites, while Leiothlypis ruficapilla had similar capture rates in both habitats. Our findings indicate that the urban green areas of cities can act as suitable quality habitat during winter for two abundant migrant birds. Our results indicate that cities can have a higher conservation potential for a declining and sensitive group such as the Nearctic-Neotropical migratory birds than previously thought. We also point out the need to acknowledge that migratory species can be urban dwellers.

Highlights

Urban areas have become the most important habitat for humans, harboring more than half of our worldwide population (Grimm et al, 2008; Elmqvist et al, 2019)
We studied migratory warblers in urban green areas (UGAs) of the city of Morelia, inside the urban matrix, and in native vegetation areas with low human disturbance located in the vicinity of the city
We evaluated how important UGAs are for wintering migrant warblers directly by evaluating the body condition of individuals of both species and indirectly by determining their abundances

Summary

Introduction

Urban areas have become the most important habitat for humans, harboring more than half of our worldwide population (Grimm et al, 2008; Elmqvist et al, 2019). While the concept of urban ecosystem is not new (Stearns and Montag, 1974), cities tend to be perceived by their human inhabitants not as ecologically functional systems but as sites with high levels of environmental degradation caused by the human disturbance of natural processes (Grimm et al, 2017; Groffman et al, 2017) This negative perception of urban systems is reinforced by the fact that some animal species from the regional pool cannot maintain viable populations inside urban areas (Fischer et al, 2015; Aronson et al, 2016). They can act as critical habitats for many regional species (Aronson et al, 2014)

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