On a cellphone tower across from the North Dade Justice Center on Biscayne Boulevard, behind a Nails 4 U and Dream Brows, a rare South Florida construction project is underway.
Two bald eagles are building a nest.
About three months ago, the pair of eagles, at least 5 years old and possibly in a family way, were spotted ferrying sticks to the top of the lofty tower. If completed, the nest would become just the fourth one in Miami-Dade County confirmed by the Florida Fish and Wildlife Conservation Commission since 1987, although not all nests are documented by the state.
“It’s amazing they’re picking a spot that’s this urban,” said Donna Molfetto, an aviation biologist with the Patricia and Phillip Frost Museum of Science, who has visited the nest four times after it was posted on an online message board.
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Considered one of the great comeback stories of conservation, bald eagles are now plentiful across the nation. Even northern parts of Florida have a healthy population, made possible by the 1960s grassroots effort that followed the publication of Rachel Carson’s “Silent Spring.” The book uncovered the lethal effects of pesticides on birds — the number of eagle nests nationwide had shrunk to just 500 — and paved the way for the modern environmental movement.
But South Florida eagles never recovered. And why remains a mystery that has puzzled ornithologists for decades.
“It’s a really odd anomaly,” said Audubon Florida Everglades research manager Peter Frezza.
With miles and miles of undisturbed wetlands, tree islands and mangrove coasts in neighboring Everglades National Park and the Florida Keys, South Florida could certainly be prime grounds for the birds, he said.
“There’s a million acres of pristine habitat,” Frezza said.
But something could be happening in the ecosystem that eagles don’t like.
Birds tend to be widely studied because they are an important indicator of an ecosystem’s health. And eagles — dubbed “sentinels” by scientists — are among the most studied because they live about 25 years, a long time in bird years, and provide lots of valuable information.
Until recently, Everglades National Park had one of the longer running data sets on eagles dating back to 1958, which peaked at about 50 nesting pairs. But about three years ago surveys stopped, said biological branch chief Tylan Dean, after new rules kicked in on using park planes. The number of pairs had dropped to the 20s at last count, he said.
“We have a lot of theories [on the decline] but we don’t know at the end of the day,” Dean said. “Over time we always hoped that Everglades restoration would improve conditions and fish [supplies], but we’re still waiting for those restoration benefits.”
South Florida’s sprawling population could explain part of the decline in eagles, Frezza said.
“But that doesn’t explain what’s going on in Everglades National Park,” he said.
One prevailing theory is that eagles left as fish they feed on disappeared, he said. Eagles usually split their diet between fish and small mammals. They’re also opportunistic feeders — landfills provide some of the best eagle-watching venues. But South Florida eagles mostly eat fish. The decline in eagles also mirrored a similar decline in other wading birds that depend on fish, according to a 2013 study.
While no longer on the endangered species list, eagles are still federally protected, making it illegal to harm or even possess any part of an eagle, dead or alive.
“Even if they drop a feather at the museum, I’m not allowed to take it home,” Molfetto said.
People also remain protective. Richard Kresge, an assistant groomer at Le Pet Salon near the base of the cell phone tower, spotted one of the eagles about three months ago while on a cigarette break but said he kept it to himself.
“I didn’t tell anyone because I thought somebody would do something stupid,” he said.
Molfetto, who will soon be working nearby at the museum’s Batchelor Environmental Center on Florida International University’s Biscayne Bay campus, which breaks ground next month, said the nest could eventually weigh a ton and measure 13 feet in diameter. The tower sits on property owned by former North Miami Beach councilman John Kurzman, who could not be reached for comment.
“Whoever owns this tower,” Molfetto said, “is going to have a massive structure on their hands.”