If you’re a fan of polar bears, few bucket list items come bigger than the opportunity to visit Churchill during bear season. Every year in October and November, Churchill’s population swells from 900 to several thousand as tourists flock to the shores of Hudson Bay, hoping to catch a glimpse of bears passing through and around town on their way to the tundra as they wait for sea ice to form on the bay’s surface.

But why Churchill? Of all the places that polar bears could congregate, why pick this former fur trading post, now the site of Canada’s most northerly passenger railway station and its only Arctic seaport?

The answer, says Geoff York, Polar Bears International’s senior director of research and policy, “is a combination of physical oceanography and geography.” Hudson Bay is one of the few places in the polar bears’ range where the ice melts completely each year, forcing all the bears in the area to come ashore during the summer months. The counterclockwise pattern of currents in the bay deposits melting ice along the southern coast of the bay, which is where bears generally come ashore, many of them holing up in earthen dens as they rest for the next several months.

Churchill sits in the bay’s southwest corner, on the northern coast of a promontory that sticks out like a snaggletooth; when the ice forms again, those same currents deposit ice floes along the protruding shore and cause them to pile up. Additionally, the area also experiences an early freeze-up because the Churchill, Nelson, and Hayes Rivers empty freshwater – which freezes at a higher temperature than saltwater – into the shallow coastal waters. The result is an early-season accumulation of ice that attracts bears, hungry after months of fasting and searching for a seal smorgasbord.

Photo: Craig Taylor

Exactly how many bears pass through Churchill and environs varies, as is evidenced by the number of bears that are handled by wildlife officers each year. (That is, how many bears enter the town itself and are physically captured and/or taken to the holding facility, popularly known as the Polar Bear Jail.) In 2003, that number was 173; four years later, it had fallen to 49, the fewest in over a decade, but in future years it would tumble: 37 in 2018, 24 in 2019. In 2020, 2021, and 2022, the totals were just four, 10, and six. In 2023, to date, officers have handled 12 bears.

One reason for that decline, says York, may be a change in human behavior in Churchill – specifically, how residents deal with their trash. Until 2005, the town’s garbage, including food waste, was piled up and burned in an open-air dump, which unsurprisingly proved a strong attraction for bears. The closure of the dump resulted in a decline in the bears that required handling, and with the passage of time, all the bears that used to visit it or remembered its existence have now died. As a result, far fewer of the Western Hudson Bay bears have any positive association between the town and food and so more are inclined to bypass Churchill itself on their way to the ice. In addition, Churchill has introduced bear-resistant garbage bins in recent years, further reducing attractants.

But other factors play a role. Most notably, there are significantly fewer polar bears in the Western Hudson Bay population than there used to be. In 1987, the population was estimated to be 1,200; by 2004 that had fallen to 935, while the most recent survey, results of which were published in 2022, produced an estimate of just 618.

The principal reason for that, of course, is that warming temperatures are causing the sea ice in Hudson Bay to melt earlier and form later, leaving polar bears with less time to hunt, and causing a decline in the size and health of bears as well as their survival and reproduction rates. But while the overall trend is clear, there are short-term wrinkles: between approximately 2016 and 2022, for example, changes in the polar vortex actually led to ice in Hudson Bay lasting until later into the summer. As a result, the bears stayed out longer and the currents deposited them farther along the coast, away from Churchill; when the ice formed again, many of those bears may have elected not to make the long trek back, almost certainly contributing to the lower numbers of bears entering town during that time.

So, many factors affect exactly where the Western Hudson Bay polar bears come ashore when the ice melts and how many gather near Churchill when it forms again. The future of the population is uncertain; but for now, Churchill remains probably the single most accessible place to see polar bears in the wild, for researchers and tourists alike. Hopefully, if we take the necessary steps to greatly reduce greenhouse gas emissions and put the brakes on global warming, it will remain a popular spot for polar bears and people alike for many, many years to come.

Kieran Mulvaney is a freelance writer who has written extensively about polar bears and the Arctic for publications including National Geographic, The Guardian, and The Washington Post. A native of Bristol, England, he lives in Bristol, Vermont.