Decline in US bird biodiversity related to neonicotinoids, study shows


Date:
August 14, 2020
Source:
University of Illinois College of Agricultural, Consumer and
Environmental Sciences
Summary:
Bird biodiversity is rapidly declining in the US. The overall
bird population decreased by 29% since 1970, while grassland birds
declined by an alarming 53%. A new study points to increased use
of neonicotinoid insecticides as a major factor in the decline.



FULL STORY ==========================================================================
Bird biodiversity is rapidly declining in the U.S. The overall bird
population decreased by 29% since 1970, while grassland birds declined
by an alarming 53%.


========================================================================== Valuable for so much more than flight and song, birds hold a key place
in ecosystems worldwide. When bird numbers and varieties dwindle,
pest populations increase and much-needed pollination decreases. Those
examples alone negatively impact food production and human health.

Likely reasons for the far-reaching and devastating declines include intensified agricultural production, use of pesticides, conversion
of grassland to agricultural land, and climate change. A new study
from University of Illinois points to increased use of neonicotinoid insecticides as a major factor in the decline, says Madhu Khanna,
distinguished professor in agricultural and consumer economics at U of
I and co-author on the paper, published in Nature Sustainability.

Khanna says numerous studies have shown neonicotinoids -- nicotine-based pesticides -- negatively affect wild bees, honey bees, and butterflies,
but large-scale studies on the pesticide's impact on birds have been
limited. She speaks more about the topic in a podcast from the Center
for the Economics of Sustainability at Illinois.

"This represents the first study at a national scale, over a seven-year
time period, using data from hundreds of bird species in four different categories - - grassland birds, non-grassland birds, insectivores,
and non-insectivores," she says.

"We found robust evidence of the negative impact of neonicotinoids, in particular on grassland birds, and to some extent on insectivore birds
after controlling for the effects of changes in land use." Khanna and co-authors Yijia Li, a graduate student at U of I, and Ruiqing Miao,
assistant professor at Auburn University, analyzed bird populations from
2008 to 2014 in relation to changes in pesticide use and agricultural
crop acreage.



==========================================================================
The authors found that an increase of 100 kilograms in neonicotinoid
usage per county-a 12% increase on average-contributed to a 2.2% decline
in populations of grassland birds and 1.6% in insectivorous birds. By comparison, the use of 100 kilograms of non-neonicotinoid pesticides was associated with a 0.05% decrease in grassland birds and a 0.03% decline
in non-grassland birds, insectivorous birds, and non-insectivorous birds.

Since impacts accumulate, the authors estimate that, for example,
100 kilograms neonicotinoid use per county in 2008 reduced cumulative grassland-bird populations by 9.7% by 2014. These findings suggest that neonicotinoid use has a relatively large effect on population declines
of important birds and that these impacts grow over time.

According to the study, the adverse impacts on bird populations were concentrated in the Midwest, Southern California, and Northern Great
Plains.

The researchers say the effect of neonicotinoids could result directly
from birds consuming treated crop seeds, and indirectly by affecting the
insect populations they feed on. Consumption of just a few seeds is enough
to cause long-term damage to the birds' reproduction and development.

The study included data on bird population and species diversity from the
North American breeding bird survey, a comprehensive database with data
from about 3,000 bird routes across the United States. The researchers correlated the bird data with pesticide use, as well as satellite data
on agricultural crop acreage and urban land use.



==========================================================================
They examined whether intensified agricultural production and
conversion of grassland to agricultural land also contributed to the bird decline. Results showed a small negative effect on grassland birds related
to cropland expansion, but no significant effect on other types of birds.

While the use of other pesticides has been flat or declining,
neonicotinoid usage has grown exponentially over the past two
decades. Neonicotinoids are considerably more toxic to insects and
persist longer in the environment, the researchers note.

"This research provides compelling support for the re-evaluation of
policies permitting the use of neonicotinoids by the U.S. Environmental Protection Agency by incorporating considerations of the implications
of these pesticides for bird habitats," the authors conclude.

The project was supported by Hatch funding from the U.S. Department of Agriculture (USDA), National Institute of Food and Agriculture (NIFA).


========================================================================== Story Source: Materials provided by University_of_Illinois_College_of_Agricultural,_Consumer and_Environmental_Sciences. Original written by Marianne Stein. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Yijia Li, Ruiqing Miao, Madhu Khanna. Neonicotinoids and decline
in bird
biodiversity in the United States. Nature Sustainability, 2020;
DOI: 10.1038/s41893-020-0582-x ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200814131023.htm

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