Local

Banding of bald eagle chicks a tall task for Kansas biologists

VIDEO: Banding bald eagle chicks

Ben Postlethwait, 38, plays an important part of an annual project that places research leg bands on some Kansas bald eagle chicks. Climbing 80 foot to the top of a cottonwood tree, Postlethwait collects three young bald eagle chicks into bags tha
Up Next
Ben Postlethwait, 38, plays an important part of an annual project that places research leg bands on some Kansas bald eagle chicks. Climbing 80 foot to the top of a cottonwood tree, Postlethwait collects three young bald eagle chicks into bags tha

MILFORD RESERVOIR – Company isn’t common when you live 80 feet up in the branches of a giant cottonwood. That’s especially true when your parents are the baddest predators in the surrounding sky.

So it’s understandable that three young bald eagles looked surprised last week when first an orange helmet, then a human face peeked over the edge of their bathtub-sized nest. At least the face was wearing a smile.

“I love it when my two passions, climbing and conservation, double up,” said Ben Postlethwait, who lowered the birds to biologists on the ground. “I can have the excitement of climbing and help in the conservation and protection of bald eagles.”

Postlethwait, 38, plays an important part in an annual project that places research leg bands on some Kansas bald eagle chicks. Such jewelry has been attached to many young Kansas eagles.

It’s part of the process that has helped document our national symbol’s rise from fears of extinction in the contiguous 48 states in the 1960s, when there were about 450 active nests in the region, to the current number of about 10,000 nests in the same region.

Kansas birds have done their share to add to the recovery. From a single nest in 1989, probably the state’s first successful nest in 100 years, bald eagles are now on the threshold of having 100 active nests in the state annually.

“At the time, we had no idea we’d be where we are today,” biologist Dan Mulhern said of the first nesting. “We hoped maybe we’d get a few more across the state, but nothing like it is now. It’s gone crazy.”

Road to recovery

Mike Watkins, a U.S. Army Corps of Engineers wildlife biologist, suspects bald eagles nested in pre-civilization Kansas. Lewis and Clark had accounts of large numbers of bald eagles along the Missouri River.

But populations were in steady decline for more than 100 years. The birds began getting some breaks when the government banned the use of DDT, a pesticide that almost completely prevented bald eagle reproduction. Rather than encouraging the shooting of eagles, as it had for decades in the 1800s, the government began strict anti-poaching programs.

It was big news when a pair of eagles nested and raised young at Clinton Reservoir.

Watkins has been around since that first nest at Clinton.

“I think we’re at 95-96 (nesting pairs) this year,” he said. “And by nesting pairs, that’s anytime we see birds that appear to be incubating or (caring for) young birds. To be honest, we probably have a few more eagle nests than that.” Eagles and nests are so common, he added, many people don’t think they’re worth reporting.

Mulhern is the U.S. Fish and Wildlife Service biologist who oversees Kansas eagles. He said this spring Kansas could produce its 1,000th eaglet since 1989. Clinton and Perry reservoirs, in northeast Kansas, have four active nests. The Arkansas River between Wichita and the Oklahoma state line has seven nests. There are 21 nests within the 13 counties that make up the south-central Kansas region, according to Charles Cope, a Kansas Department of Wildlife, Parks and Tourism biologist.

“If we have a problem, it’s that we have so many nests we can’t keep track of them all,” said Mulhern.

During the first few years, biologists captured and placed identifying leg bands on all bald eagles born in Kansas. This year, six nests are scheduled for visits. Mulhern said about 240 eaglets have been banded within Kansas since 1989. From the bands, and the process of attaching them, biologists gather important data, he said.

“For one thing, we’re getting a look at demographics and that lets us predict future growth based on the number of male birds we find,” he said. “Most males come back and nest close to home while the females take off and nest with whatever male they find. That could be in a big winter concentration, so one of our females could end up nesting in Canada.”

Of particular interest, biologists know that the male that fathered those first chicks in 1989 is still producing young in Kansas and has to be at least 31 years old. The 26-year-old chicks from that first nest, both males, are still nesting in eastern Kansas, too.

The bands on their legs allow biologists across North America to see where adults in their area may have hatched. As the birds are being banded, biologists take weights and measurements to help determine the health of the birds compared with past years.

The first few years, biologists caught freshly fledged eagles in live traps. In 1993, they began enlisting the aid of volunteer climbers to remove 6-week-old eaglets from the nests. Mulhern said at that age the birds are about adult size physically, yet don’t have enough feather development to fly away.

Climbing for success

Born in Wichita, Postlethwait has a biology degree from Fort Hays State and is coordinator of Westar Energy’s Green Team, which helps fund, and staff with volunteers, a variety of conservation projects. Climbing is his passion.

He’s a lifelong outdoors enthusiast and got into rock climbing about 10 years ago. He’s made trips across the western United States, as well as Nepal and the Alps, to climb, and has a climbing wall in his garage so he can work with his young daughters.

Postlethwait has been the official eagle project tree climber for three years. He said there’s a sizable difference between climbing a giant tree to access an eagle’s nest and scaling rock walls.

His first duty last week at Milford was to use a slingshot to shoot a lead ball and string over a strong-looking branch high in the nesting tree. A rope was tied to the string and pulled over the branch. One end of the rope was tied to Postlethwait’s climbing harness. The other end was passed through a harness that Watkins wore on the ground, so he could control the rope should Postlethwait fall or need support.

To his feet and ankles Postlethwait strapped tree climbing spikes – as long and sharp as an eagle’s talons – that thrust straight down from his instep. Each hand held an 18-inch-tall ice climbing pick, with serrated teeth to help him grip the tree.

It took more than half an hour for Postlethwait to scale the tree. After nearly every step up he’d test the trunk, bark and nearby limbs with the picks before raising his feet higher.

“How it goes depends a lot on the species of tree,” Postlethwait said. “I don’t trust cottonwoods. Had it been a big sycamore, I’d have felt a lot more comfortable.”

Several obviously dead branches near the tree’s top concerned Postlethwait, as did several areas where large chunks of bark fell. He later said the tree was getting treacherous. Even though the eagles will probably return to the same nest next spring, he won’t be climbing the tree.

“I have a wife and two daughters to think about,” he later told Watkins. “It’s not worth it to try it again (next year).”

One of the trickiest parts of a climb is accessing the nest, which can stretch several feet past the supporting limbs. Postlethwait often attaches ropes to branches above the nest and uses them to help climb aboard.

No matter how tough the going, Postlethwait said it’s important to speak softly and move slowly.

“I have to be as calm and fluid as possible, talking softly to the birds when I get into the nest,” he said. Startled eaglets not yet able to fly could jump from the nest and to their death.

So far, the Kansas program has had no banding-related bird fatalities, Mulhern said. At a second nest that day, a bird that was at least 9 weeks old flew from the nest as the climber approached. It was captured, banded and placed back in the nest. Its future is uncertain, which is true for all young bald eagles.

Fewer than 20 percent of eaglets survive their first year. Many fly into utility lines or starve as they try to learn to be good hunters.

One of the three eaglets hunkered down at Postlethwait’s approach in the nest. The other two raised their wings to make their already goose-sized selves look bigger. Both parents circled overhead, calling in protest. Mulhern said an adult Kansas eagle has never attacked humans during the banding operations.

The eaglets calmed after Postlethwait eased them into cloth bags. On the ground, Mulhern and helpers weighed the 6-week-old chicks, which ranged from 8 to 10 pounds, and attached two aluminum bands to the birds’ legs. One band was dull and covered with tiny numbers and letters. The other was brightly colored with larger characters so it could be read with binoculars or a spotting scope from a distance. All of the information was eventually placed in a national database that’s easily accessed by biologists.

Blood ran from Mulhern’s hand after the largest of the young eagles got in a few grabs with its 2-inch talons. Waiting above, Postlethwait hauled all three bagged birds up at once. Tired from the ordeal, they caused few problems as he placed them in the nest before rappelling down the tree.

On the ground, he described how the biggest of the birds had been the first to ever come at him as he accessed the nest, pecking him repeatedly on the helmet. The headgear certainly prevented some deep wounds from the adult-sized bill.

“I guess I deserved that,” he said. “I’m up in their house, so they can treat me like they want.”

Reach Michael Pearce at 316-268-6382 or mpearce@wichitaeagle.com.

Bald eagle facts

At least 31 years old, the male bald eagle that helped make the first nest in Kansas in modern times in 1989 is one of the oldest ever found in the wild.

Most bald eagles nest near rivers or lakes so they can prey on fish, but they’ll eat a wide variety of meat. Ben Franklin was opposed to them being named America’s national bird because they often steal food from smaller birds and eat carrion.

Bald eagles mate for life, but will take another mate when theirs dies.

Bald eagles can spot a moving rabbit up to a mile away. Soaring at 1,000 feet, they can spot prey across 3 square miles.

Average wingspan for a female is more than 7 feet.

The largest recorded bald eagle nest was in Florida and measured 9 1/2 feet in diameter and 20 feet from top to bottom, weighing an estimated 4,500 pounds.

Adult bald eagles normally weigh 6 1/2 to 14 pounds. Females are much larger than male bald eagles.

Bald eagles usually don’t nest until they’re about 5 years old, which is about the time their head becomes totally white.

Related stories from Wichita Eagle

  Comments