Scientists Find More Than 2 Billion Birds Mirate Over the Gulf Coast Every Spring

Until now researchers have been making a best guess at the number of birds passing over the Gulf of Mexico during their spring migration, but a new study has found there are more than two billion making the annual trek.

Habitats along the Gulf of Mexico provide a wide variety of migratory birds who travel through the area annually from their wintering grounds in the  southern U.S., Caribbean, and Central and South America with vital resources as they head to their breeding grounds in North America in the spring.

While small surveys have given researchers an idea about the number of birds passing through, researchers using data from citizen scientists from the Cornell Lab of Ornithology’s eBird app combined with weather radar stations have now estimated that there are more than two billion birds making the trip each spring.

“We looked at data from thousands of eBird observers and 11 weather radar stations along the Gulf Coast from 1995 to 2015,” said the study’s lead author Kyle Horton, an Edward W. Rose Postdoctoral Fellow at the Cornell Lab of Ornithology. “We calculated that an average of 2.1 billion birds crosses the entire length the Gulf Coast each spring as they head north to their breeding grounds. Until now, we could only guess at the overall numbers from surveys done along small portions of the shoreline.”

Their work, which was just published in the journal Global Change Biology, also resulted in some other new discoveries, including finding half of the individuals that pass through the region do it in just 18 days, between April 19 and May 7, with about one billion passing through in just that short time. Researchers also found that five times as many birds migrate through Texas than other states surrounding the Gulf.

“The highest activity, with 26,000 birds per kilometer of airspace each night, was found along the west Texas Gulf Coast,” said Horton. “That region had 5.4 times the number of migrants detected compared with the central and eastern Gulf Coast from Louisiana to Florida.”

Gulf_Coast_Spring_Migration_Kyle_Horton
Credit: Kyle Horton/Cornell Lab of Ornithology

For migratory birds, who researchers note in their study are declining, knowing when and where exactly they are migrating could have major conservation implications. They’re already threatened by habitat loss, predators, collisions with structures and being drawn by artificial light, and now climate change, which is altering their environment and availability of resources, is posing yet another challenge.

“If birds aren’t changing their migration timing fast enough to match the timing for plants and insects, that’s alarming,” added Horton. “They may miss out on abundant resources on their breeding grounds and have less reproductive success.”

Yet if we know where the most important areas are for them, it could lead to better efforts to protect them during peak migration, which, according to the study’s authors, could include actions like turning off lights and wind turbines, which are known threats.

For more on how to get involved in citizen science projects that could contribute to research like this, check out the Cornell Lab of Ornithology.

Photo credit: Getty Images

57 comments

Richard E Cooley

Thank you.

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Tabot T
Tabot T5 days ago

Thanks for sharing!

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Christine Stewart

thanks

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Ruth S
Ruth S6 days ago

Thanks.

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Ruth S
Ruth S6 days ago

Thanks.

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Olivia M
Olivia M8 days ago

thanks for sharing

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Adeline A
Adeline A8 days ago

Please do whatever can be done to protect them.

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Chrissie R
Chrissie R8 days ago

Except for the ones killed by wind turbines.

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Danuta W
Danuta W9 days ago

Thanks for posting.

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Anne H
Anne H9 days ago

Brilliant

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