At 8:30 on a Sunday morning, most of the Grafton campus is quiet. But in the McGrath Veterinary Anatomy Laboratory at Cummings School of Veterinary Medicine at Tufts University, a group of veterinary students is already hard at work, preparing to weigh, photograph, and meticulously dissect a handful of dead loons. 

The birds were found around Massachusetts—mostly on Cape Cod—and were either already dead or unable to be saved. For one, the cause of death is obvious: its mouth and head are still tangled in yellow-green fishing line. Another had a severe fungal infection, which becomes clear as the students take a look inside its chest. 

“We try to learn as much as we can from every loon that comes through here,” said Mark Pokras, D.V.M., V84, an associate professor emeritus at Cummings School of Veterinary Medicine.

Pokras has been leading loon necropsies—the term for an animal autopsy—since the late 1980s. The necropsies are not part of any class, but he never has trouble finding veterinary students willing to showing up on the weekend to x-ray and dissect the birds. 

“Veterinary students have completely spoiled me as an educator—they’re incredibly bright, incredibly motivated, incredibly idealistic, and they’re always hungry for something to get their hands on,” said Pokras, who served as the director of the Tufts Wildlife Clinic from 1995 to 2008. “With their help, we’ve generated tons of good science.”

Over the course of the morning, the students examine every inch of the birds, inside and out. Pokras and the more experienced students move from table to table, helping to spot anything unusual and offering tips on the best way to identify thyroid glands or remove the digestive tract. The students collect various samples of feathers, tissues, and stomach contents from each bird. 

“Each of those samples go off to different researchers or research labs who are doing their own individual loon work,” said Isabel Eisendrath, V26, who began helping with loon necropsies during her first year at Cummings School. “Ultimately, all that information is compiled and can help contribute to loon conservation.”

One major contribution from the years of work done by Pokras and his students has been to shine a spotlight on lead poisoning in loons. Loons frequently ingest pebbles from lake bottoms to help break down food in their stomachs, and can mistakenly scoop up lost lead fishing weights at the same time. They may also eat fish with lead fishing gear still attached. From the stomach, lead quickly enters a loon’s bloodstream, causing weakness and neurological problems. Most animals die within a few weeks. 

Data from necropsies conducted by Pokras and his students over more than two decades showed that 48% of loon deaths in New Hampshire were the result of ingesting lead tackle. These findings encouraged New Hampshire and several other states to begin to regulate lead fishing gear. 

New Hampshire’s regulations have helped, but lead fishing gear is still getting into the state’s loon population, said Katie Baxter, V27. Baxter attended one of Mark’s loon necropsies during her first year as a veterinary student and spent last summer working with the Loon Preservation Committee, a nonprofit organization in New Hampshire.

“We conducted around 30 necropsies over the summer and six showed severe lead poisoning as the cause of death,” Baxter said. “I was shocked to see so many, because it’s a law that you can’t use that kind of fishing gear anymore.”

The laws vary from state to state, but work led by a recent Cummings School graduate, Jillian Hojsak, D.V.M., V24, recently helped to close a loophole in Maine’s legislation. Previously, Maine allowed small-scale lead fishing gear to be used if it was painted, assuming that the paint would keep the lead contained. Hojsak conducted a summer project using rock tumblers to demonstrate how quickly the paint would abrade away in the acidic, grinding environment of a loon’s gizzard—the lower part of their stomach. 

“We showed pictures of that work to a legislative hearing and passed a new piece of legislation that now, starting in 2025, we’re going to have painted fishing gear covered in Maine too,” Pokras said. “Jillian’s summer project is the reason that the legislation passed.”

These summer opportunities are primarily funded by Shalin Liu, a long-time donor to the Tufts Wildlife Clinic who owns the Summer Star Wildlife Sanctuary. Pokras coordinates with nonprofit conservation organizations conducting loon work as well as several diagnostic and university labs to help students learn the skills they need for their own professional journeys. 

“It’s a dance every year with what I want to get done, what the students are interested in learning, and what our collaborators are interested in doing,” Pokras said. “We have a long list that ranges from field work to laboratory molecular genetics to toxicology, and every year we try to see how it all fits together.”

Karli Fletcher, V25, spent a summer splitting her time between field work and lab work. She helped the Vermont Loon Conservation Project with a long-running loon population survey, including banding some of the birds. And, in a lab at the University of Vermont, she used tissue samples from several years of loon necropsies to look at incidences of avian malaria, which was first detected in a loon in 2015 and is one of several emerging diseases that may be related to climate change. 

“I loved the laboratory experience, because it was something new for me. I’d never done research before,” Fletcher said. “But the field work was great too. I really enjoyed having the combination of both.”

The work gave her a new love for the unusual birds and, although she plans to go into small animal medicine, she hopes to find other opportunities to help wildlife where she can.

Many veterinary students who assist with the loon work head into general practice after they graduate, but for those that want to pursue a career working with wildlife, Pokras is more than happy to help them get started. It’s a field he has been navigating for over 40 years and, despite the fact that he is technically retired, his students report that he still has connections everywhere.

“One of my great joys is trying to help students who have similar interests figure out how to negotiate their professional pathways and get where they want to go,” Pokras said.

So Emilie Gurnon, D.V.M., V23, knew exactly who to reach out to when she realized she didn’t want to go into general practice. After she graduated, Pokras helped her get a job for the summer and fall seasons as a pathologist with the Loon Preservation Committee. Gurnon conducted necropsies during the day and at night, joined her colleagues in canoes, playing recorded loon calls across pitch black lakes to draw the animals close enough to catch and band. She even helped relocate an abandoned loon chick to the nest of an adult pair whose eggs were not viable, watching the parents return and accept the chick as their own. 

“It solidified my interest in and love of the field work and wildlife aspects of a vet career,” Gurnon said. She now works in the lab of Jonathan Runstadler, D.V.M., Ph.D., professor in the Department of Infectious Disease and Global Health at Cummings School of Veterinary Medicine, conducting surveillance for the current avian influenza outbreak. 

There was a point where the vast majority of the loon necropsies in New England were conducted by Pokras and his students. (“Around the region, people refer to me as the dead loon guy,” Pokras joked.) But since he retired in 2015, Pokras has been training groups in Maine, New Hampshire, Vermont, Massachusetts, and across the U.S. to conduct their own necropsies and contribute information and samples to a massive communal database. 

“We’re approaching our 5,000^th dead loon, and we’ve got tissue samples saved in freezers from all of them, back to the first one,” Pokras said. “Even with a species as well-studied and as charismatic as common loons, the questions keep arising. And every question you ask generates more potential projects for students.”