Wildlife authorities keep finding dead and sick bald eagles on Maryland’s Eastern Shore—a poisoning mystery that stretches back at least three years.

Most recently, seven eagles and one owl were found dead in Kent and Talbot counties since March 1, while a handful of sick eagles were nursed back to health. In 2016, 13 dead eagles turned up dead from the same banned pesticide: carbofuran. Maryland agriculture and natural resources officials said last week they were working together to address its continued illegal use, and in a tweet on Friday, Gov. Larry Hogan urged anyone who still possesses the chemical to contact the Maryland Department of Agriculture for proper disposal.

Few people are more knowledgeable about threats to bald eagles than William Bowerman, a professor of environmental science and technology who has spent his career studying the birds, and whose research has been instrumental in their resurgence and removal from endangered species status. He spoke recently to Maryland Today about the Eastern Shore eagle deaths.

Why would someone poison bald eagles? Was this likely intentional, or accidental?
People have different attitudes toward wildlife. Possibly there’s a fear of wildlife, or this may be a dominionistic person who believes that man controls all wildlife species, or maybe they view the eagles as predators that could impact their cattle or sheep or other livestock or pets, even.  It’s definitely an intentional act.

Do eagles frequently make off with chickens and Chihuahuas?
It’s a pretty rare occurrence. But it has happened when there is very, very low food availability. Bald eagles primarily eat fish, birds, turtles and mammals that live around the water, so we're not really seeing them go after their chickens or any other livestock.

How can wildlife authorities nail the perpetrator?
That's a very difficult thing for our law enforcement people because this is a colorless, odorless compound—carbofuran—that’s put out in a bait. They would have to figure this out with legal forensics and criminal investigation who actually poisoned them. It has a very quick action, and it's difficult to catch someone doing it. Someone could have thrown it out of a car window. They could leave it in a remote area where people typically don’t go.

Besides the dead eagles that were found, are there likely others?
I would imagine that there are multiple other eagles that have not been found. Eagles have probably died and just ended up on the forest floor where no one has found them. So it’s very likely more than 20.

Does this affect the eagle’s conservation status?
The loss of 20-plus eagles is not a major threat. In 1961 there were 484 pairs of bald eagles across the lower 48 states. Just in the greater Chesapeake Bay region now, there's over 2,000 pairs of nesting eagles. If you go back to when I started working on eagles the in the early 1980s, we would never have predicted that they would have come back that strongly.

Eagle populations plummeted decades ago because of environmental poison, but was that different?
It was. Right after World War II, we started using a lot of organochlorine pesticides, particularly DDT, which caused a lot of problems with egg shell thickness and porosity within the eggs, and that decreased the eagle populations every single year. When the Endangered Species Act was enacted in 1973, we didn't know for sure that eagles or peregrine falcons would even be in the wild at this point in 2019.

What’s your take on the recent United Nations report that human activity has put a million species at risk for extinction?
Thankfully, this current specific local poisoning event is not having a major population impact for the bald eagle. But we see that larger threat to species from human activity in other things we work on, such as trying to save vultures in Africa, where we do have very significant poisonings with the same compound. People will try to kill lions, or poachers kill elephants and intentionally poison the carcasses. We end up with 400, 500, 600 dead vultures. So poisoned carcasses are threatening vultures’ existence on the entire African continent.