SALISBURY — These things take time.

For the past month and a half, bald eagles Liberty and Justice did everything by the book. Liberty laid two eggs. She and Justice, her mate, dutifully kept those eggs warm through the incubation period.

They did plenty of protective squawking whenever people came close to the nest, which was built in the crook of large limbs at the Robert Lee Honbarrier Bald Eagle Habitat of Dan Nicholas Park.

But the eggs’ due date for hatching came and went without any signs of life.

Bob Pendergrass, Nature Center supervisor at Dan Nicholas Park, gave the would-be parents 10 extra days with the nest, just in case, but each day meant the American bald eagles and park staff were closer to a sobering truth.

The eggs were not fertile.  Pendergrass made the purposeful climb toward the eagles’ nest Thursday morning to collect the eggs, so Liberty and Justice could stop their futile efforts toward ever seeing eaglets poke through the shells.

“They won’t try to incubate anything that’s not here,” Pendergrass said.

As he reached the nest, Pendergrass found two perfectly shaped eggs, mostly a dull white in color.

“I think they are both formed fine,” he said. “It’s just a matter that they were never fertilized.”

Liberty and Justice, while a bit perturbed, gave Pendergrass plenty of room around the nest. He knew they wouldn’t be aggressive, he said, because nature dictates that animals with the ability to reproduce go with their instinct to survive first.

They wanted to be sure they were around for another try.

The nest had a thin top layer of pine needles and evergreen twigs, which provide a chemical aroma to deter insects, such as mosquitoes.

“We’re going to try and get out of here as soon as we can,” Pendergrass said, dropping the eggs into a soft tote bag.

Later, in the environmental center, Pendergrass conducted a test to make sure the eggs were not fertile.

He has considerable experience in breeding birds of prey such as cooper hawks, barn owls and falcons. But bald eagles were new for him.

Pendergrass fashioned a slide projector so that the light came through only a pinhole in the bottom of an aluminum can. With the thin beam of intense light, he examined each egg for any sign of a blood vessel network or embryo.

A uniform darkness was all he could see.

“My opinion is,” Pendergrass said, “there’s never been any development of the eggs.”

Pendergrass’ contacts with the Carolina Raptor Center in Huntersville said the center’s bald eagles laid eggs for five years before any eaglets were hatched (in 2006).

Pendergrass believes with high certainty Liberty and Justice, who are each 10 years old, will keep trying. Expect more eggs in late December or next January, he predicts.

“I’m disappointed — I guess that’s a selfish sort of thing,” Pendergrass says. “(But) I think they’ll work it out. They’ve come a long way from my saying they’ll never breed.”

Liberty and Justice came to Dan Nicholas Park in 2006 from a rehabilitation center in Florida. They are both disabled and could not survive in the wild.

Pendergrass thought for years they would never breed, given their disabilities — Justice essentially has only one wing that works — and the limited room for flying in the habitat.

It severely tests any instincts they might have for aerial courting.

But the eagles showed a new kind of industriousness in building a nest last summer, and the first egg showed up in the nest Jan. 12, followed by another egg Jan. 15.

Pendergrass knew from the start the chances of the eggs being fertilized were iffy, but he had even persuaded himself they were going to hatch.

“In my mind, I was giving this 100 percent (chance of happening),” he said. “Laying them is one thing, but their dedication to the eggs was another.”

Eagles in captivity are highly regulated. Pendergrass will contact the U.S. Fish and Wildlife Service to see if he’ll be permitted to void the inside of both eggs and put them on display for educational purposes at the Nature Center.

Pendergrass remains optimistic. He expects Liberty and Justice to keep adding bulk to their nest this summer and mate again.

It’s nature’s way.    Contact Mark Wineka at 704-797-4263,or mwineka@salisburypost.com.