The muskox burger at Saxifrage Resto-Café, in the far northern hamlet of Cambridge Bay, costs $27. That’s not outlandish in a place that takes at least two days and three separate flights to reach from Toronto, and where a small honeydew melon can set you back $15. But muskox is local “country food”—or at least, it used to be.

Cambridge Bay is a dent in the southern shore of Victoria Island. Along with neighbouring Banks Island, the area is home to one the world’s biggest muskox herds. For as long as anyone can remember, the local Inuit have relied on the shaggy ice-age beasts for food, clothing, and shelter (they’re a pain to clean and dress compared to easily skinned cariboo, one local hunter told me—but the payoff is worthwhile.) So it’s worrying that muskox numbers in the area have plummeted by 70 per cent in the last few years alone.

I was in town to report on the new Canadian High Arctic Research Station, or CHARS, an ambitious research facility due to open its doors in 2017. But (don’t tell my editors) I was also wearing my tourist hat, eager to experience summer above the Arctic Circle. Seeing omingmak—the Inuit name for muskox, meaning “bearded one”—was at the top of my list.

It didn’t take long to discover that muskox-spotting wouldn’t be easy.

“They’re just not around anymore,” Stephane Lacasse, the manager at the Kitikmeot Foods processing plant, told me. “The herds are quite small, and they don’t come toward town.” Lacasse’s plant processes about 70,000 pounds of Arctic char each year, most of which it ships to southern markets. Until 2012, the company also ran a commercial muskox hunt, hiring local hunters to bring in a few hundred animals each year. But as the herds began to thin, the local community made a collective decision to suspend the commercial hunt until numbers recover.

Despite the reprieve, muskox numbers have continued to drop. In June, a team of researchers led by Dr. Susan Kutz of the University of Calgary advanced another theory, in a paper published in the Canadian Veterinary Journal. In the summer of 2012, about 150 muskox carcasses were spotted on Banks Island; testing revealed the presence of a bacterium called Erysipelothrix rhusiopathiae that’s commonly found in livestock like pigs and turkeys. Further tests have confirmed that the bacterium is present in muskox across Banks and Victoria islands—and, crucially, it seems to be a new development, since retesting of old muskox blood samples from the 1990s has come up negative.

So what’s happening? Kutz and her colleagues are just starting to unravel the mystery. I accompanied them to a remote research camp across Dease Strait from Cambridge Bay, where they were trapping lemmings—potential disease vectors—and collecting muskox poop to test a theory about how E. rhusiopathiae is spreading. (Lemmings may seem tiny and inconsequential, but they play a vital role in the Arctic ecosystem, Kutz points out: “If polar bears disappear, nothing changes. If lemmings disappear, we lose a whole lot of species.”)

Whatever the precise sequence of events, it’s likely that warmer temperatures are playing a role in the northward spread of pathogens and parasites. The Arctic is heating up twice as fast as anywhere else in the world, and Kutz’s earlier research showed that hotter summers now allow lungworms, an increasingly common parasite in muskox, to complete their reproductive lifecycle in one year instead of two. In the case of E. rhusiopathiae, the bacteria’s effects may be magnified when the animal is under stress, for example from overheating. Even when it’s only 15 degrees Celsius, the round-the-clock Arctic sun can heat the soil to 30 or 35 C—uncomfortably hot for muskoxen in their dark, heavy coats, Kutz points out.

In the end, the only muskoxen I spotted during my trip were seen through the open door of an aging Beaver float plane several hundred metres above the tundra. A few years ago, a flight like this would have revealed large family groups dotting the countryside in every direction; this time, we spotted only three lonely animals—one pair and one singleton.

We don’t know exactly how bad the muskox die-off is because we have only a very rough idea of how many muskoxen there used to be, let alone how many there are now. Tens of thousands have apparently died in a short time, but researchers have only been able to find and analyze a few corpses thanks to the remoteness of the terrain.

They’re eager for any clues they can get, though, and asked us to bring back any marrow-filled long bones we saw so they could analyze them. That’s the current reality of most Arctic research and is one of the reasons a permanent research station in Cambridge Bay will be so important.