Marshall Lee Weimer is pictured on Isle Royale. (Courtesy photo)

ISLE ROYALE — I was on the hunt for teeth.

The rich, dark, wet earth forced itself under my fingernails as I scratched through roots and a few beetles.

But no teeth. I needed those teeth.

Or that’s what Clay Ecklund, my expedition leader, told our team of volunteer bone seekers on Isle Royale National Park. I squatted in the middle of a thick cedar swamp with John Warming and Lada Zednik. Nearby, Hal Hanson, another member of our group, sat behind a few downed trees, resting from an arduous hike through nearly unnavigable terrain.

There was another presence. Or what remained of one. We were at a moose calf’s final resting place, trying to piece together its skeleton. All the bones were there, the mandibles, the metatarsus, parts of the skull. But no teeth. We needed the teeth.

I couldn’t tell where I was. I knew I was on an island wilderness in the middle of Lake Superior. But where exactly on the island, only the GPS knew that. North was somewhere over my left shoulder.

We were sweaty, exhausted and fighting off the summer’s first mosquitoes. We had gotten turned around an hour earlier and realized we had to go through the cedar thicket to find another water source.

Most people don’t experience national parks this way, especially on their first visit. But I had the special opportunity to participate in a volunteer backpacking expedition known as the Moosewatch Expedition. Since 1988, the expedition has sought volunteer backpackers for a citizen science project. You set off from the dock where the boat from the mainland drops you and then hike deep into the backcountry. The goal is to collect as many moose bones as you can in a weeklong trek across the island. There are four expeditions from mid-May to late July.

This is easier said than done. This expedition is completely off-trail, meaning no paved paths, trail markers or campgrounds. Navigation is done with a compass and a pocket GPS marked with kill site coordinates, places where scientists know wolves have eaten moose.

We arranged our five-member group into a long, spread out line. We then all hiked forward into the wilderness, keeping our eyes peeled for bones. When a bone or antler is found, you shout “BONE!” to the rest of the team. That was the cue to fan out and search the area for the creature’s remains. We carried the bones we found to a central location where the team leader cataloged and photographed the partial skeleton.

All bones must be carried out on foot as there are no roads on the island. Thankfully, not all the bones need to be carried out. Only the skulls, mandibles (the jawbone) and metatarsus (the foot bone) are needed. The teeth I was looking for help determine a moose’s age. These bones tell the researchers all they need to know about the moose.

The volunteer expedition has helped build the world’s largest collection of moose bones, she said. Those bones help researchers study other things.

Among them is air quality. Moose store heavy metals from the air in their teeth. Researchers measured the impact of the U.S. Clean Air Act by analyzing the heavy metal content of moose teeth. Since the bone collection is so old, they could compare lead and mercury levels in teeth from before and after the law was strengthened in 1970. Researchers saw heavy metal levels in the teeth drop dramatically in the early 1980s, showing that air quality had improved.

Disease is another thing the bone collection helps us understand. We learn a lot about human arthritis from moose arthritis, said Rolf Peterson, a research professor who has studied the wolves and moose of Isle Royale for over 50 years. Isle Royale moose have an unusually high rate of arthritis compared to mainland ones.

My expedition recovered the remains of 26 moose. But I never did find those moose teeth. Nor did I see a moose. But I found so much more. The island is full of life, both human and inhuman. I saw sucker fish spawning and spiders crawling. And, for the first time, I heard wolves howling.