Bird communities threatened by urbanization

Date:
August 24, 2021
Source:
University of Go"ttingen
Summary:
Urbanization is one of the most drastic forms of land-use
change. Its negative consequences on biodiversity have been studied
extensively in countries like Germany. However, there has been less
research in tropical regions from the Global South. Researchers
investigated the effects on farmland bird communities in Bangalore
and found that urbanization filters out species with certain traits,
such as insect-eating birds, which are important for pest control.



FULL STORY ========================================================================== Urbanization is one of the most drastic forms of land-use change, and
its negative consequences on biodiversity have been studied extensively
in temperate countries such as Germany. However, less research has been conducted in tropical regions from the Global South, where most of the
ongoing and future urbanization hotspots are located, and little is
known about its effects on agricultural biodiversity and associated
ecosystems. A research team from the University of Go"ttingen and
the University of Hohenheim, in collaboration with the University of Agricultural Sciences of Bangalore in India, investigated the effects
of urbanization on farmland bird communities in and around Bangalore,
a city of over 10 million inhabitants in South India. They found that urbanization homogenizes farmland bird communities, filtering out
species with certain functional traits, such as insect-eating birds,
which are important for pest control. The results were published in
Global Change Biology.


==========================================================================
A local ornithological expert conducted regular bird surveys over one
year and recorded 126 bird species. Using remote sensing techniques,
satellite pictures were processed to produce a map of different land-uses,
from which urbanization intensity was measured based on the proportion of sealed surfaces and buildings in the landscape. The researchers analyzed
how farmland bird communities changed along a gradient of urbanization
using newly developed statistical analyses.

"We found that urban bird communities were impoverished subsets of rural communities, both in terms of species composition and the ecological
functions they provide," says first author Gabriel Marcacci, PhD
student in the Functional Agrobiodiversity group at the University
of Go"ttingen. "Birds perform important roles in the environment,
for instance controlling pests by eating insects, scavenging and
removing carrion, or eating fruits and dispersing the seeds. But
only bird species that are well adapted to urban environments such
as pigeons or crows can thrive." "The homogenization -- resulting
from losing diversity through the exclusion of certain groups -- of
farmland bird communities may disrupt important ecosystem functions
and services in urban agroecosystems such as pest removal by insect-
eating birds," explains Professor Catrin Westphal, head of the Functional Agrobiodiversity group. Urban communities were found to be more sensitive
to species loss, endangering ecosystem resilience.

"Our study underscores urbanization as a serious threat to biological communities and ecosystem functioning that may affect food production
systems," adds Professor Ingo Grass, head of the Department of Ecology of Tropical Agricultural Systems at the University of Hohenheim. Professor
Teja Tscharntke concludes, "This concern is especially relevant for
countries from the Global South where urban agriculture and ecosystem
services play an increasingly important role for food security." ========================================================================== Story Source: Materials provided by University_of_Go"ttingen. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Gabriel Marcacci, Catrin Westphal, Arne Wenzel, Varsha Raj,
Nils No"lke,
Teja Tscharntke, Ingo Grass. Taxonomic and functional homogenization
of farmland birds along an urbanization gradient in a tropical
megacity.

Global Change Biology, 2021; DOI: 10.1111/gcb.15755 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210824174441.htm

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