Tag Archives: bald eagles

Saving our nation’s symbol on national wildlife refuges

Bald Eagle

Bald eagle at Eastern Neck National Wildlife Refuge in Maryland. Photo by Thomas Barnes.

National Wildlife Refuges have a special connection with the protection and recovery of some of our country’s most iconic species. The three refuges highlighted below share a special connection with our national symbol – the bald eagle. Thanks in part to conservation efforts at these refuges and others, bald eagles successfully recovered and were removed from the list of threatened and endangered species in 2007.

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Credit: Katrina Krebs / USFWS

 Elizabeth Hartwell Mason Neck National Wildlife Refuge in Virginia was established in 1969 as the first national wildlife refuge established explicitly for the protection of bald eagles. All who love the refuge (and eagles) can thank Elizabeth Hartwell, a local resident, who did not want to see Mason Neck peninsula commercially developed and organized an effort to conserve the area. The refuge currently contains 2,277 acres of land, including forest, marsh and riverine habitat and lies 18 miles south of Washington D.C. on the banks of the Potomac River. Mason Neck is part of the Potomac River National Wildlife Refuge Complex.

Did you know that bald eagles are believed to mate for life? Click here to learn more about their breeding habits.

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Credit: Tim Kaufman / USFWS

 Montezuma National Wildlife Refuge in New York was established in 1938 as a refuge and breeding ground for migratory birds and other wildlife. The refuge is the site of the country’s first bald eagle hacking program. The term “hacking” is not as morbid as it may sound. It only means to release young bald eagles to the wild. The program began in 1976 as an effort between the Service and the New York State Department of Conservation in an effort to reintroduce the bald eagle to the state. From 1976 to 1980, a total of 23 bald eagles were released at the refuge as a result of the hacking program.

Did you know that DDT, which was heavily used as a pesticide prior to 1972, helped contribute to the temporary downfall of bald eagle populations across the country? Click here to learn more about how it happened. DDT was banned in 1972 by the Environmental Protection Agency. 

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Bald eagle at the USFWS Northeast Regional Office in Massachusetts. Credit: USFWS / Rosie Walunas

Rappahannock River Valley National Wildlife Refuge in Virginia was established in 1996 to conserve and protect fish and wildlife resources. It is also Virginia’s largest wintering roost for bald eagles! You can find them roosting and nesting throughout the refuge. When you visit, be sure to find mature canopy trees overlooking creeks and you may see a bald eagle. The refuge is part of the Eastern Virginia Rivers NWR Complex.

Did you know that the oldest recorded bald eagle in the wild was 38 years old? Click here to learn more about this fact and others.

Next time you are in the area of one of these refuges make sure to stop by. You may just be lucky enough to spot a bald eagle!

 

Wednesday Wisdom – Rosalie Edge

 

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Original image by Don Freiday/USFWS

Spotlighting conservationist Rosalie Edge (1877-1962) as we celebrate #WomensHistoryMonth; part of #HerStory is her legacy and leadership to establish the Pennylvania-based Hawk Mountain Sanctuary.

Hawk Mountain Sanctuary was the first privately acquired property for the sole purpose of conservation.  It was considered the model for The Nature Conservancy by one of TNC’s co-founders, Richard Pough.  Today, Hawk Mountain is visited by tens of thousands of visitors every fall to witness the migration.  The data gathered at the Hawk Mountain Sanctuary about immature hawk and eagle migration were very helpful to Rachel Carson in making her case against DDT.

Rosalie Edge’s legacy energized future conservationists to restore healthy bald eagle populations and the eagle was finally delisted under Endangered Species Act protection on August 9, 2007.  Though the bald eagle was not common by the time the species nearly disappeared from most of the United States, its federal protection  was hugely instrumental in returning our “national symbol” to the skies.

The two main factors that led to the recovery of the bald eagle were the banning of the pesticide DDT and habitat protection afforded by the Endangered Species Act for nesting sites and important feeding and roost sites. This recovery could not have been accomplished without the support and cooperation of many private and public landowners. Go here for more information about the recovery and delisting of the Bald Eagle.

Don Freiday’s fabulous bald eagle image was shot at the Cape May National Wildlife Refuge

Kodiak National Wildlife Refuge. Credit: Dave Menke/USFWS

Why do our bald eagles have high levels of lead, mercury?

A recently released report shows that toxic levels of mercury and lead were found in the livers of bald eagle carcasses recovered in New England. The researchers, Steve Mierzykowski of our Maine Field Office, Charles Todd of the Maine Department of Inland Fisheries and Wildlife, and Mark Pokras of Tufts University Cummings School of Veterinary Medicine, share their insights with us today.

Steve Mierzykowski, a senior fish and wildlife biologist in our Maine Field Office, holds an immature bald eagle. Credit: USFWS

Steve Mierzykowski, a senior fish and wildlife biologist in our Maine Field Office, holds an immature bald eagle. Credit: USFWS

What did they find?

Between 2001 and 2012, the researchers collected liver samples from 127 bald eagle carcasses from Connecticut, Maine (mostly), Massachusetts and New Hampshire. They analyzed the liver tissue for lead and mercury.

  • 14 percent had lead concentrations indicative of poisoning. Other North America eagle studies report similar or higher percentages.
  • The average mercury level (13.49 parts per million dry weight) was higher than average levels recorded in eagles from British Columbia, several Great Lakes states and Alaska.

Check out the rest of the report.

Q. Why are we concerned about lead and mercury levels in eagles? A. Lead and mercury are both potentially long-lasting in the environment. At low levels of exposure, their direct influence may go unnoticed.

However, long-lived animals like bald eagles may suffer from chronic accumulations that eventually impair their reproduction or survival. Lead is rapidly mobilized in an eagle’s gastrointestinal tract. Certain bacteria can methylate mercury: the new organic by-product, methylmercury, passes through the food web in increasing concentrations to top-level predators like eagles.

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An X-ray of this bald eagle shows lead in its gizzards — see the bottom right of the eagle’s body. Credit: Mark Pokras, Tufts University

Although we have a good understanding of the acutely toxic effects of lead on bald eagles (and other species), we feel that it is particularly important to enhance our understanding of chronic, low-level effects. Lead has significant effects on the brain, heart, kidneys and many other organ systems. There are indications that such levels may predispose eagles to traumatic injury as well as impairing reproduction and survival.

Documenting the effects of toxic materials like lead and mercury in charismatic species like bald eagles can also help to alert policy makers and the public to current and emerging wildlife health threats.

Q. What has interested or surprised you during your research on this topic? A. High exposure rates to mercury to bald eagles in Maine were a surprise to many.

Point sources for mercury contamination are more often associated with industrialized regions, but this contaminant does circulate widely in the atmosphere. Maine is downwind of many industrialized regions of North America.

The high rate of exposure to lead among Maine eagles during fall, winter and spring is also troubling. Whether this is an artifact of increasing eagle numbers in the state, or possibly related to milder winters so that more eagles remain in the state year round, it is clear that scavenging carrion that may contain lead is a risk for eagles during periods of the year when ice cover restricts normal fishing habits of Maine eagles.

 

Q. Will you continue to study these levels in eagles? A. As budgets allow, we will continue to investigate contaminant levels in bald eagles. Lead, mercury and newly emerging contaminants like flame retardants will be measured in tissues of bald eagle when funds are available. The monitoring plan for bald eagles (after their recovery under the Endangered Species Act) has a contaminant component, and everyone recognizes that keeping track of contaminant levels over time and periodically assessing these levels are important to the species.

Because eagles are a highly charismatic species that sparks great public interest, and because they sit atop the food chain in a variety of habitats, bald eagles are an important sentinel species for representing a variety of environmental threats. Lead, mercury and other contaminants are known to affect their health, and the health of a wide variety of other species.

Q. How might people be able to help reduce this problem in the long term? A. Clearly, more research and public education are needed regarding non-toxic bullets, shot and other sporting gear, such as fishing weights. Unrecovered lead bullets and shotgun pellets in animal carcasses present a continuing health threat to scavenging species like the bald eagle.

See other contaminants research from our Maine office, including contaminants in crossed bill bald eagles, in eagles at Acadia park and our Maine coastal refuges, in eagle eggs and brook trout.