One of the bald eagles found dead in a farm field on Maryland’s Eastern Shore over the weekend. A total of 13 were found. (Courtesy of Maryland Natural Resources Police)

The carcasses of 13 bald eagles that were found over the weekend in a field on Maryland’s Eastern Shore have been sent to a forensic laboratory in Oregon that’s been dubbed the CSI lab for animals, where they will undergo a thorough analysis to figure out what caused their deaths.

The eagles were discovered Saturday by a man who told authorities he was out on the property looking for antlers deer had shed when he saw what he thought was a dead turkey. Turns out it wasn’t.

It was four dead eagles, and after wildlife officials searched the area, they found nine more dead eagles in the field near the intersection of Richardson and Laurel Grove roads in Federalsburg.

There were no obvious signs of trauma to the birds. And it was not immediately known what exactly killed them, said investigators from the Maryland Natural Resources Police and the U.S. Fish and Wildlife Service. But there are several theories, including that they died from some sort of poison. It is the largest single such incident of dead eagles in 30 years in the state, experts said.

The 13 dead bald eagles found in a field on Maryland's Eastern Shore have been sent for analysis to the National Fish and Wildlife Forensic Lab, the CSI of labs for animals, in Ashland, Ore. (Courtesy of National Fish and Wildlife Forensic Laboratory)

The carcasses were sent Monday night to the National Fish and Wildlife Forensic Laboratory in Ashland, Ore., , officials said. The federal lab has been dubbed the “CSI for Animals” in an article by Boston’s NPR station. In its promotional information, the lab bills itself as a crime lab that is “very much like a ‘typical’ police lab, except the victim is an animal.”

The rare forensic lab was founded in the 1980s. Officials there have told of how they often get a wide range of evidence from eagle talons to decomposed boa constructors, wolves and skunk carcasses.

Officials at the lab said the 13 eagles from Maryland will go through the same process as other carcasses: They’ll be physically examined by vet pathologists, X-ray images will be taken, and samples of liver, stomach, kidney, urine and blood will be collected and analyzed. Screenings will also be done to look for possible poisons, and a necropsy will be conducted.

The lab has about 30 employees and a $5 million annual budget. It examines 100 to 1,000 cases a year that involve about 15,000 items ranging from feathers to carcasses.

In Maryland, there are theories — lots of them.

One is they were poisoned. An area landowner may have sprayed a chemical on a field and that could have adversely impacted the eagles. Or poison used to kill rodents could be the culprit. The rodents may have died outdoors, then the eagles ate the carcasses and were poisoned in turn.

Ed Clark, president and founder of the Wildlife Center of Virginia, said there are two most likely scenarios of how the eagles died. They may have eaten carcasses left from a euthanized horse or cow. Or they ate bait that was laced with poison that was intended for coyotes or other predators — a practice that Clark said is illegal.

“Whatever killed those birds, they didn’t get far, and that means it was extremely toxic,” Clark said.

Eagle experts recalled other cases involving large-scale deaths of eagles.

In 2008, authorities tried to get rid of a hefty rat population on an island in Alaska by using poison. But gulls and eagles were attracted by the scent of the dying rodents, and 46 eagles ended up dead, according to Ellen Paul, executive director of the Ornithological Council.

Another theory is there could be something like botulism or a naturally occurring blue-green algal toxin that got into area vegetation. Waterfowl eat that vegetation and then the eagles may have eaten the waterfowl and died.

“Thirteen [eagles dead] in one spot is either something natural occurring, or there was some type of poison involved,” said Bill Bowerman, an eagle expert and head of the Department of Environmental Science and Technology at the University of Maryland.

Experts say that vehicles are one of the biggest killers of bald eagles these days. As development has encroached on their habitat, eagles are eating less fish and are scavenging more. They often are hit by vehicles as they eat carcasses on roads or are sickened from eating out of dumps or landfills, experts said.

In Maryland, there is a $10,000 reward being offered from several agencies and groups for any information in the recent Eastern Shore case.

The 13 dead bald eagles that were found this weekend included at least three mature birds, with the signature white heads and brown bodies. Two of the birds were close to maturity, officials said, and the rest were considered immature, with no white feathers.

Bald eagles are no longer on the endangered species list, but they are considered a protected species, according to the Natural Resources Police.

Last year, 18 raptors died from gunshot, poisoning or getting entangled in fishing lines or landscape netting, according to the Tri-State Bird Rescue and Research. Raptors include eagles, hawks and owls. An official with the organization said that 13 other raptors who suffered similar incidents were rehabilitated and returned to the wild.

Thirty years ago, eight bald eagles were found dead in Maryland. Officials said they think those birds may have been poisoned.

And two years ago, two bald eagles were shot and killed in one week in Montgomery County. It is illegal to shoot eagles without a permit from the U.S. Department of the Interior.