GRAND RAPIDS, Mich. (WOOD) — The bald eagle has represented the pride and strength of the United States for more than 240 years. But after being pushed to the brink of extinction, only recently has the regal bird’s population bounced back in Michigan.

According to the Department of Natural Resources, a recent survey found approximately 900 breeding pairs of bald eagles in Michigan. That number is way up from past surveys — 359 confirmed breeding pairs in 2000 and 83 in 1980 — and far away from where the bird stood in the 1950s and 60s. In 1963, federal authorities estimated there were only 417 nesting pairs of bald eagles across the entire continental United States.

Erin Ford, a conservation manager for the Great Lakes chapter of the National Audubon Society, says three key factors nearly led to the bird’s extinction, all caused by humans.

“Before 1940, bald eagles were hunted by people because they were a perceived threat to livestock as well as fisheries,” Ford explained to News 8. “And then they also lost a lot of their preferred nesting and roosting habitat. They really like being in trees that are adjacent to a water body, so when we see a lot of shoreline development — and historically they prefer to stay from human development — they lost a lot of their preferred habitat.”

But the big blow came when a new pesticide was introduced to the market in the 1940s that caused then-unprecedented chemical pollution. The pesticide was called dichlorodiphenyl trichloroethane, commonly known as DDT.

Chemical pollution is nothing new. It has been a growing problem worldwide for the past century. From DDT to PCBs, PBB and now PFAS, researchers continue to learn more about how the chemical age has impacted the planet.

An updated study by researchers at Boston College estimated pollution is a factor in one of every six human deaths each year — approximately 9 million people. Pollution remains “the world’s largest environmental risk factor for disease and premature death,” according to the researchers.

At first, DDT was considered a scientific breakthrough. It was an effective tool for protecting crops and livestock from insects and other pests, and it cut down on the spread of several insect-borne diseases, including malaria and typhus. But the chemical pollution caused by the insecticide had unintended consequences.

Evidence mounted that DDT had serious negative effects on the environment. The U.S. Department of Agriculture, which regulated pesticides before the Environmental Protection Agency was launched in 1970, started changing regulations in the late 1950s. Author Rachel Carson made DDT a national concern with her 1962 book “Silent Spring” that detailed the dangers of chemical pollution.

According to the EPA, DDT is extremely durable in the environment. It can travel long distances in the upper atmosphere and accumulates in the fatty tissue of animals. That accumulation spelled major trouble for the bald eagle.

“The toxicity of (DDT) increased as you move up the food chain,” Ford said.

DDT treatments would eventually leech into nearby water systems, or insects exposed to DDT would end up in the food chain, eaten by fish or other small animals. Those creatures were then eaten by the eagles.

“Bald eagles were impacted in a couple of different ways (by DDT). It thinned their eggshells, so when they would try to incubate the eggs, they would crack. (DDT) also caused other breeding problems, physical issues, other side effects that were causing them not to breed successfully,” Ford explained.

Regulators eventually banned DDT altogether. Michigan banned the pesticide in 1969 — the first state to do so — three years before the nationwide ban.

But the fallout left the bald eagle critically endangered, and it was up to conservation groups to step in and rehabilitate the few remaining bald eagles and reintroduce them into the wild.

Ford says the 1973 Endangered Species Act was pivotal to helping those groups coordinate and save the bald eagle.

“The Endangered Species Act provided bald eagles with extra precautions as an endangered species, but more importantly, provided funding to actually implement conservation strategies that would help bring them back,” Ford said. “It allowed conservationists and researchers to partner with one another across state lines and across agencies to help develop different rearing and releasing programs across the country to stabilize the population.”

Over the last several decades, Ford says new forestry practices have also made a big difference while bald eagles have learned to adapt to their new surroundings.

“There are some areas where that preferred nesting habitat has come back. But we are also seeing bald eagles adapt to more urban landscapes, too. We are starting to see their greatest expansion in the southern half of the state where most of (Michigan’s) largest cities are,” Ford said. “We are learning, and they are learning as well.”

The bald eagle was removed from the federal endangered species list in 2007. In 2020, the U.S. Fish and Wildlife Service estimated there were more than 315,000 bald eagles across the continental United States, with more than 70,000 breeding pairs.

Still, there are simple actions you can take to help protect the bald eagle from manmade obstacles.

“One of the continued threats to their population is lead poisoning. So, for outdoor enthusiasts, if you can use alternative shot instead of lead shot, try to avoid using lead tackle. That would be helpful for bald eagles,” Ford said. “And just take your time to properly pick up your trash, especially if you are near a water body. Fishing line, properly dispose of that. Those are things that can cause them to get tangled up or eat something they shouldn’t be eating.”

Ford also reiterated the importance of keeping your distance from a large wild animal.

“A general rule of thumb is to try to limit any activity that could disturb them during nesting season. Try to keep a distance of a few hundred feet, especially with any big, loud activity,” Ford said. “With drones getting more popular, too, flying a drone around any eagle or raptor nest isn’t a good idea. … Osprey in particular are really sensitive to disturbances. Bald eagles seem to be a little less sensitive, but they could potentially attack a drone and take it down. They will defend their nest if they feel threatened.”