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Then-Secretary of the Interior Dirk Kempthorne (R) and Al Cecere, president and CEO of the American Eagle Foundation, holding Challenger, a bald eagle, during ceremonies at the Jefferson Memorial in Washington recognizing the removal of the bald eagle from the list of threatened and endangered species, in 2007. (Karen Bleier/AFP/Getty Images)
It’s that time of year again when faithful scientists, volunteers, and bird enthusiasts take to the field to count bald eagles in their areas and help the scientific community monitor the status of the once endangered species.
The Midwinter Bald Eagle Survey is an annual event first started by the National Wildlife Federation in 1979 in order to provide a count of wintering populations for the eagles in the lower 48 states, as well as gather data on their habitats and population distribution. This year the survey runs for about two weeks, from Jan. 4 to Jan. 18.
“The survey is a true public-private partnership with hundreds of volunteer citizen scientists taking part, in addition to federal, state, and NGO biologists,” said Wade Eakle, the 2012 national survey coordinator and an ecologist for the U.S. Army Corps of Engineers according to the U.S. Geological Survey newsroom. “Forty-three states continue to actively participate, with over 740 standardized survey routes across the country.”
The Midwinter Bald Eagle Survey’s hundreds of workers continue to tread along routes in the field hoping to gather accurate counts of these birds during the winter.
After field data is collected, it is sent to a national database for further processing. The goal is to identify winter habitats and develop a total population index for the eagles during their wintering months. The survey utilizes a variety of field methods to gather data needed: about 44 percent of the surveys are taken from vehicles, while 18 percent are taken from fixed wing aircraft, 8 percent from boats, and 7 percent from helicopter.
“Collecting data over the long-term helps scientists and wildlife managers monitor the health of bald eagle populations. The power of this survey is continuity,” continued Eakle. “Because it’s been run every year since 1979, we have a lot of confidence in what we can now say about the status of wintering bald eagles in the United States.”
Bald eagles were in decline since European settlers first started encroaching upon their habitat. However, eagle populations were not so violently threatened until the 20th century. Even though laws were passed in the early part of that century to protect the eagle from humans, the commercially used pesticide DDT posed problems for the birds in the past, including problems with the bird’s reproductive process.
Additionally, approximately 100,000 eagles were killed in Alaska during the first half of the 20th century for fear that the eagles were damaging Alaska’s salmon industry.
President Nixon signed the Endangered Species Act in 1973, which brought a great deal of attention to wildlife conservation efforts in America and throughout the world, including the rapidly disappearing bald eagle. The U.S. Fish and Wildlife Service declared the bird a national endangered species on July 4, 1976.
Today, it is estimated there are approximately 70,000 bald eagles worldwide, with about half of those birds living in Alaska and another 20,000 living in British Columbia. The eagles seem to prefer the northwest coast of North America, thriving on local salmon.
After data is added annually into the national database, it is compiled with the previous year’s data to help create a long-term analysis examining the bird’s patterns over a long period of time. An analysis for the 25 years between 1986 and 2010 will be released this spring.
“Periodic analyses of the counts are a key,” continued Eakle. “They are useful to scientists working to analyze the effects of climate change, habitat loss, and other impacts on bald eagles.”