Midwinter Bald Eagle Survey

By Jean Flick  

                                             

On a cold day in January, a group of hearty individuals, led by Paul Balkenbush, Hagerman National Wildlife Refuge Deputy Manager, searched the Texas side of Lake Texoma for the presence of bald eagles.  HNWR has supported the Midwinter Bald Eagle Survey for a number of years, providing bald eagle counts that are used to estimate trends of wintering bald eagle populations across the lower 48 states.

Each January, several hundred individuals count eagles along standard, non-overlapping survey routes as part of this nationwide survey.  Started in 1979, counts were first coordinated by the National Wildlife Federation and are now coordinated by the U.S. Army Corps of Engineers (USACE). 

Paul Balkenbush coordinates this effort for the Texas portion of Lake Texoma.  The 2018 survey was completed in one day in January, by individuals who were each assigned portions of the shoreline area between Highway 69/75 and I-35.  Team members may travel by boat or vehicle to search for eagles, with most choosing to travel by vehicle.  This year, the team completed 859 minutes of survey time with 67.3 miles of shoreline observed.  Bald eagle sightings included 4 adult and 8 immature eagles.

Paul reports the team’s data, including the time spent and miles observed.  This data, including the number of eagles/shoreline mile and number of eagles/survey hour is compiled from regions across the country and can then be used to support bald eagle relative density estimates.

The USACE website provides summary trend tables from 1986-2010, which show an overall increasing trend in eagle sightings in the majority of national regions (6 of 9 regions) but an overall decreasing trend in sightings in Texas during that same time period.  A wide range of variables may impact this data.

The USFWS considers the recovery of bald and golden eagles to be a conservation success story.  When the bald eagle was adopted as our national symbol in 1782, the country may have had as many as 100,000 nesting eagles.  By 1963, with only 487 nesting pairs of bald eagles remaining, the species was in danger of extinction. Loss of habitat, shooting, and DDT poisoning contributed to the near demise of our national symbol.

The Endangered Species Act was enacted in 1973, and in 1978 the bald eagle was listed as endangered throughout much of the contiguous U.S.  Habitat protection afforded by the Endangered Species Act, the federal government’s banning of DDT, and conservation actions taken by the American public have helped bald eagles make a remarkable recovery.  Bald eagles were removed from the endangered species list in August 2007 because their populations recovered sufficiently.  (USFWS Endangered Species website and Fact Sheets)

Data from a variety of sources, including estimates from the annual Midwinter Survey, contribute to our body of knowledge regarding the continued successful recovery of bald eagle populations.  Paul is always looking for members to join the Bald Eagle Survey team.  Participation is open to any interested birder who wants to spend a day looking for eagles along the lakeshore.  Contact Paul at the refuge office if you would like to participate on the team in January 2019.

Photo Credit:  Bald Eagle at HNWR by Brian Fant

Eagle Week at HNWR

We are unofficially designating this week as Eagle Week!  Two eaglets are in the first ever eagles’ nest at Hagerman National Wildlife Refuge, definitely worth celebrating, and we were invited to give a program on the Bald Eagle this week for the Pottsboro first graders.

Young eagles at HNWR, by Rick Cantu

Of all the more than 300 species of birds that are on the Hagerman NWR bird check list, the one most visitors say they want to see is the eagle.  And now that there are several nests going in the Texoma area we should be able to see them regularly year around.

The Bald Eagle was adopted as the national emblem in 1782 and serves as a symbol of wilderness and freedom. Benjamin Franklin said that the Bald Eagle was a bird of bad moral character (stealing food) and recommended the turkey instead. I wonder if the turkey had been chosen, what we would eat for Thanksgiving?

Eagles are one of our largest birds –  they just weigh about 10 – 14 pounds but envision the size of an eagle’s wingspan – the first graders held a tape measure indicating the wingspan measurement of  a whopping 6 – 7’5’ !!

Bald eagles have white feathers on their head and tail - but not until they get to be about 4 – 5 years old; often this makes viewers think they are seeing a Golden Eagle rather than a young Bald Eagle – You might wonder about the name bald…a long time ago bald meant white, not “hairless”.

Bald eagles are very good hunters and have terrific eyesight.  The students learned that if they could see as well as an eagle they could stand on the playground and look down the street to a mile away and see a tennis ball in the grass there.

Watching the video, A Home for Pearl, we learned that Bald Eagles make a very big nest of sticks high up in a tree or on the edge of a cliff.  They use the nest again and again, making it bigger every year.  How big?  One really huge eagle nest was over 9’ across – we had to use the tape measure again…. AND it weighed 2 TONS!! That’s about the same as 80 kids all added up – so 80 first graders stood up for comparison.  That particular nest was reused over and over for 34 years.

Paralleling changes in the national eagle population, Texas Parks & Wildlife reports, as noted  in the May edition of the Featherless Flyer,  indicate that from 1971 – 2005 the number of known active eagles’ nest in Texas increased from  5 to 160.  Nationally, after recovering from, first, being hunted, and then affected by DDT, they are no longer considered endangered or threatened; however the eagle population is considered threatened for Texas.

And that reminds me of the last fact I want to tell you – Most eagles can live for up to 20 years…the oldest one we know about lived to be 48 years old.

Note:  The location of the eagles’ nest at Hagerman is known only to Refuge staff and is strictly “off-limits” for visitors, for the protection of the birds.  Attempts by visitors to find it will jeopardize the continued use of the nest.

Eagle-mania

The number one request from visitors at Hagerman National Wildlife Refuge is "Where can I see an eagle?"  Everyone wants  to see our national symbol with its 6 - 8 foot wingspan, soaring overhead, but only a few are fortunate enough to do so, and the time and place is largely unpredictable.  Eagles do winter at Lake Texoma  as well as below the Denison dam, and year-rounders have been seen in the vicinity of the dam. The eagle shown below was photographed by Joe Blackburn at the Refuge in February, 2013.

The eagle has played a special part in American culture, being chosen as the national symbol in 1782, and then following a sharp decline in population due to loss of habitat, being hunted as a predator on fish and livestock, and finally impacted by DDT, nearly becoming extinct.  In 1940 Congress passed  the Bald Eagle Protection Act, and various laws during the 1960's listed both the Bald Eagle and the Golden Eagle  as endangered or threatened and began providing protection for both species.  Then Rachel Carson's book, Silent Spring, led to the banning of DDT in 1972, and the species began to recover.

A few Bald Eagle facts, from the U. S. Fish & Wildlife Service:

• Females are larger than males, weighing about 14 pounds and having an 8 foot wingspan, as opposed to ten pounds and a six foot wingspan for the males.
• Bald eagles are mostly dark brown until they reach 4 -5 years in age.
• They live near rivers, lakes and marshes where they can find their primary food - fish.  they will also eat small animals and carrion.
• Eagles mate for life, building nests ten feet across in the tops of large trees or alternately in cliffs or even on the ground where there are no trees.
• Bald eagles may lay one - three eggs, which hatch in about 35 days; a month after hatching, the young are flying on their own.
• Approximately 70% survive the first year of life, and the eagle lifespan may be as long as 15 - 25 years in the wild.

If your quest is to see an eagle when you visit Hagerman during the cold weather months, keep your eyes to skies!