Light pollution increasing year round for some migrating birds
Southeastern U.S., Mexico, & Central America of greatest concern
Date:
March 31, 2022
Source:
Cornell University
Summary:
Nighttime light pollution levels are increasing the most in the
southeastern United States, Mexico, and Central America--findings
based on year-round data collected over the last two decades in
the Western Hemisphere.
FULL STORY ========================================================================== Nighttime light pollution levels are increasing the most in the
southeastern United States, Mexico, and Central America -- findings
based on year-round data collected over the last two decades in the
Western Hemisphere. This trend is a real concern for birds that fly at
night during spring and fall migration and even during non-migratory
seasons. Results of the study by the Cornell Lab of Ornithology and
Colorado State University are published in Ecosphere.
==========================================================================
"The southeastern United States, Mexico, and especially Central America
are important migration corridors," said lead author Frank La Sorte
at the Cornell Lab. "Evidence that nocturnally migrating birds are
encountering increasing light pollution levels within these regions is concerning. Birds largely avoid light during the breeding and non-breeding season. During migration, however, these associations break down as birds travel across a wide range of habitats, including populated areas that
contain higher light pollution levels." Light attracts and disorients
birds during migration, often leading to injury and death after collisions
with buildings. The authors found that light pollution levels during the
past two decades have gone up over roughly 16% of the land area in the
Western Hemisphere, with another 7% of land area experiencing a reduction
in light pollution. Declines in light pollution are concentrated in the northeastern United States in conjunction with human population declines
and urban decay in large cities (map).
The study used data from eBird to generate weekly estimates of relative abundance for the 42 study species. eBird is a Cornell Lab citizen-science program in which volunteer bird watchers enter their observations from
anywhere in the world. The authors intersected the weekly abundance
estimates with satellite-based measures of year-round light pollution
compiled over a 22-year period.
Scientists found that all 42 bird species they studied occurred in
regions with increasing light pollution levels. The strongest increases occurred during migration, especially for birds that migrated through
Central America. The weakest increases occurred for birds that spent
the summer breeding season in the northeastern United States.
"Reversing light pollution trends in Central America, especially during
the spring, and launching Lights Out programs during intense migration
periods could save a substantial number of migrating birds," added study co-author Kyle Horton at Colorado State University. "Reversing light
pollution trends in the southeastern United States during the summer
breeding season and in Central America during the winter non-breeding
season would generate the greatest benefits outside of migration periods."
The hope is that by determining where and when birds are likely to
encounter existing or increasing light pollution will lead to more
effective efforts to reduce risks and increase bird survival.
========================================================================== Story Source: Materials provided by Cornell_University. Note: Content
may be edited for style and length.
========================================================================== Journal Reference:
1. Frank A. La Sorte, Kyle G. Horton, Alison Johnston, Daniel Fink, Tom
Auer. Seasonal associations with light pollution trends for
nocturnally migrating bird populations. Ecosphere, 2022; 13 (3)
DOI: 10.1002/ ecs2.3994 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/03/220331151212.htm
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