One of the longest-running citizen science projects in the world has kicked off its 125th annual event.
The Christmas Bird Count (CBC), administered by the U.S.-based nonprofit National Audubon Society, takes place each year from Dec. 14 to Jan. 5. The annual bird census collects valuable data that scientists use to track the health and distribution of bird populations across the Western Hemisphere.
The CBC got started in 1900 with a handful of conservationists who wanted to promote counting, rather than hunting, birds. Today, tens of thousands of people volunteer for the count each year at more than 2,600 different locations, spanning more than 20 countries across the Americas.
The westernmost Christmas Bird Count takes place on the island of Guam in the Pacific Ocean, which is located 19,000 kilometers (12,000 miles) west of Recife, Brazil, where the easternmost CBC is held. The northernmost count occurs in the Arctic Bay, while the southernmost count is conducted aboard a U.S. National Oceanic and Atmospheric Administration research vessel in the Drake Passage, off the southern tip of South America.
“People count birds in all sorts of ways, like just your typical walking and going out in cars [and they] go out on dog sleds or on horseback. We had someone talk about how folks were going out in horse and buggy to count birds,” Cooper Farr, manager of community science at the National Audubon Society, told Mongabay in a phone call.
The CBC’s idea is to count all the birds you can see or hear in a 24-hour period in a 24-kilometer (15-mile) radius. The data collected is then compiled in a database by Audubon and made freely available for scientific use.
“To date we have documented more than 300 peer-reviewed scientific projects that came out of Christmas Bird Count data,” Farr said.
One of the most famous studies to use CBC data is the 2019 so-called three billion bird study, which found that North America has lost nearly 3 billion birds since 1970.
Other researchers have used CBC citizen-science data to document the distribution of bird species and show how they’re responding to climate change and changing land use.
Luisa Moreno, who organizes the CBC in Monteverde, Costa Rica, told Mongabay that CBC observers there have seen dramatic changes in bird distribution over the 31 years of the local count.
“The white-breasted wood wren [Henicorhina leucosticte] is becoming more common as you go uphill from the lower parts like from Los Llanos coming up to Monteverde,” said Moreno, who is also a research coordinator with the Monteverde Institute. “They’re becoming more common uphill just because of the change in the climate.”
Anyone, from a birding novice to an expert, can join a bird count circle near them and participate in the Christmas Bird Count.
This article by Bobby Bascomb was first published by Mongabay.com on 20 December 2024. Lead Image: A male cardinal in winter. Image by William Klos via Flickr (CC BY 2.0).
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