Taking flight: Annual Tahoe eagle count monitors species, numbers higher in 2021
The crisp air chills the group of bird watchers as they sit on the pier at Zephyr Cove, on Lake Tahoe’s South Shore, waiting for bald eagles to show themselves.
One of the bird watchers comes from Sacramento every year to sit on the same pier to count bald eagles with the Tahoe Institute of Natural Science.
Since the 1980’s, groups have gone out once a year to count the number of bald eagles they see within a three-hour time period.
The National Midwinter Bald Eagle Survey was started by the National Wildlife Federation in 1979 to monitor the status of bald eagles. U.S. Geological Survey took it over in 1992 with the help of U.S. Army Corps of Engineers but NWF still participates in the survey.
“Tracking eagle populations, their recovery over the past several decades and increases today has become a joint example of collaborative conservation and coordination across the public sector, the private sector and thousands of committed individuals,” said Kevin Coyle, vice president for education for the National Wildlife Federation in a press release about the 2019 count.
Bald eagles were listed as a protected species in 1940 but after the introduction of DDT (Dichlorodiphenyltrichloroethane) into the environment in 1945, the number of bald eagles started dropping at an alarming rate. DDT, a synthetic insecticide, caused their eggs to thin; so many eggs broke or never hatched.
According to an article by NWF, when the bald eagle was named the U.S. national symbol in 1782 there were about 10,000 nesting pairs. By 1963, there were about 417 nesting pairs left.
DDT was banned in 1972, and the number of bald eagles began rising and in 2007, they were removed from the endangered species list with an estimated 9,789 breeding pairs.
“It’s nice to see how conservation and change in behavior can make an impact,” said Sarah Hockensmith, Outreach Director at TINS.
“Every year is different, and weather conditions, as well as how much snow is in the trees, impacts detection rates, but we have seen a fairly steady, increasing trend since the beginning of the survey at Tahoe (in 1979) up until a few years ago,” Hockensmith said.
The 2020 eagle watch saw 24 bald eagles, 17 adults and seven immatures.
“Since 2014, tallies have usually been in the low 20s, with one year spiking to 27, and last year dipping to 19. As we hover around this recent average, we question if the carrying capacity of Lake Tahoe can provide for 23 eagles,” Hockensmith said.
Hockensmith also said lately, eagles have been moving down Carson Valley earlier each year to feed on the afterbirth of cows and scavenge dead calves.
“This may be a result of climate change, but calving season, and the exodus of many of Tahoe’s eagles, has definitely been shifting forward in the calendar year,” Hockensmith said.
While DDT is no longer a prevalent threat to eagles, they are not free from danger. Nowadays, the threat comes from wind turbines.
Save the Eagles International estimates California’s Altamont Pass wind farm killed an average of 116 Golden Eagles annually. That number came from a four- year study started in 2004.
There are limited numbers of eagle permits available through the U.S. Fish and Wildlife Service that allows permit holders to take eagle nests under special circumstances.
“As the nation seeks to increase its production of domestic energy, wind energy developers and wildlife agencies have recognized a need for specific guidance to help make wind energy facilities compatible with eagle conservation and the laws and regulations that protect eagles,” FWS states on their website.
They’ve released guidance to help companies prevent taking or moving nests unless absolutely necessary. The pacific southwest region of FWS has issued six permits, four to solar companies, one to a mine and one to a solar company.
A company called IdentiFlight has built a sensor to be placed on wind turbines that will sense several species, including bald and golden eagles, and will stop the turbine before the bird reaches it. This technology has been installed on towers all over the world and the company claims that over two million birds have been detected and countless have been saved.
About 10 years ago, TINS took over organizing and leading the annual eagle count at Lake Tahoe. On the second Friday of the year from 9 a.m. to noon, volunteers spread out to 26 locations around Lake Tahoe to look for birds. This year, about 90 volunteers came to count.
TINS board member Rich Chambers said it’s important to do it the same time and way each year for more consistent and accurate numbers.
Hockensmith said winter is the best time of year because the eagle facts, and relive some of their favorite birding moments.
Their passion for birding is contagious and even when there are no eagles in sight, they are genuinely happy to be out there. However, when there is a bird sighting, the excitement is palpable. Ten minutes before the count was set to end, two adult eagles take to the sky near the Upper Truckee Marsh, with one of them still holding its prey in its talons.
Volunteers from Lake Forest Beach and 64 Acres saw the same two eagles work together as a team to try to get a duck but gave up after fifteen minutes.
“This was a really incredible show of determination by the eagles, and must have cost a great deal of energy,” Hockensmith said. Hockensmith, who has seen hundreds of eagles, said seeing them never gets old.
To learn more, visit http://www.tinsweb.org.
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