Which Traits Influence Bird Survival in the City? A Review

Ravi Jambhekar,Swaroop Patankar,Kulbhushansingh Ramesh Suryawanshi,Harini Nagendra

doi:10.3390/land10020092

Abstract

Urbanization poses a major threat to biodiversity worldwide. We focused on birds as a well-studied taxon of interest, in order to review literature on traits that influence responses to urbanization. We review 226 papers that were published between 1979 and 2020, and aggregate information on five major groups of traits that have been widely studied: ecological traits, life history, physiology, behavior and genetic traits. Some robust findings on trait changes in individual species as well as bird communities emerge. A lack of specific food and shelter resources has led to the urban bird community being dominated by generalist species, while specialist species show decline. Urbanized birds differ in the behavioral traits, showing an increase in song frequency and amplitude, and bolder behavior, as compared to rural populations of the same species. Differential food resources and predatory pressure results in changes in life history traits, including prolonged breeding duration, and increases in clutch and brood size to compensate for lower survival. Other species-specific changes include changes in hormonal state, body state, and genetic differences from rural populations. We identify gaps in research, with a paucity of studies in tropical cities and a need for greater examination of traits that influence persistence and success in native vs. introduced populations.

Highlights

Today, urbanization presents a major threat to biodiversity [1,2]
Ecology published the most papers on trait adaptations in urban birds, followed by Urban
This study showed that the urban bird community had a larger variance in Flight initiation distance (FID) when compared to rural bird communities, but this variance decreased with increase in time since urbanization

Summary

Introduction

By 2050, 68 percent of the world’s population will live in urban areas [3]. Ecologically speaking, urban areas are highly modified and fragmented habitats, in the form of several managed and unmanaged urban green spaces, like public and private garden, nature reserves within the city, vacant plots, to name a few, which are capable of providing resources to a small number of highly adaptable species of fauna [2,4,5,6]. The urban greenspace along with the biodiversity it harbors, forms a unique ecosystem within the human dominated landscapes, capable of providing several ecosystem services to the cities [2]. Ecosystem services are the services that are beneficial to humans as a result of naturally occurring processes [10], which render them all the more important in human dominated landscapes, like cities

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