A solitary wolf has carried out an action that seems more fitting for a nature documentary than a heavily populated European region.
Tracking data analyzed by the KORA Foundation reveal that a male wolf identified as M637 swam across Lake Lucerne, covering approximately 0.93 miles (1.5 kilometers) on February 13, 2026. The crossing took place in water measured at around 41°F (5°C), with a GPS location point recorded directly in the middle of the lake.
Researchers describe this as the first confirmed instance of a wolf swimming across this Swiss lake. Beyond its novelty, the event provides valuable insight into how wolves navigate landscapes shaped by human activity, sometimes choosing direct but risky paths.
A Cold-Water Shortcut Captured by GPS
According to officials in Lucerne canton, tracking data indicate that M637 entered the water near Küssnacht and exited roughly 0.93 miles (1.5 kilometers) away on the opposite shore, rather than traveling around the lake by land. The cold water conditions alone would present a significant challenge.
The wolf had been fitted with a GPS collar by the KORA Foundation in late October 2025. Movement records show that M637 had already traveled extensively—from the Jura region in Vaud across the Swiss Plateau, into the Emmental, and through the canton of Zug.
On February 13, the GPS collar recorded a direct route across open water. Based on estimated swimming speed and environmental conditions, the crossing could have taken around 90 minutes.
While it remains uncertain whether M637 is the same wolf observed in Oberägeri two days earlier, the lake crossing itself is supported by strong tracking evidence. It highlights how GPS monitoring can uncover behaviours that would otherwise remain unnoticed.
Why Dispersing Wolves Take Such Risks
M637 is believed to be a male wolf aged between three and four years—an age when many wolves leave their original pack in search of territory and a mate. This stage, known as dispersal, often involves long-distance travel and encounters with unfamiliar environments.
During this period, wolves face decisions similar to young adults in human society, but with higher stakes. They must find food, avoid conflict, and locate suitable habitat.
From the wolf’s perspective, crossing the lake may have been the most efficient option. Traveling around the shoreline could have meant passing through populated areas, encountering domestic animals, or navigating busy roads. A direct swim, despite the cold and risk, may have reduced exposure to human activity.
What GPS Tracking Reveals—and Its Limits
GPS collars do not provide continuous real-time tracking like smartphone applications. Data points can be irregular, sometimes spaced hours or days apart, and signal gaps can occur in difficult terrain.
These collars are also designed with a timed release mechanism so they eventually detach, ensuring the animal’s long-term welfare. As a result, tracking data offers only a partial view of an animal’s movements.
Even so, the February 13 data stands out because it includes a location point in the middle of the lake. For researchers, this detail provides strong evidence that the wolf swam across, rather than simply moving along the shoreline.
Wolves Navigating a Densely Populated Landscape
Although Switzerland appears small geographically, it contains dense infrastructure, including roads, railways, and urban development. Despite these challenges, wolves have been gradually returning to the region.
Biologist Flurin Kunz of the KORA Foundation noted in an interview with SRF that while this is the first documented lake crossing of its kind in Switzerland, similar events may occur more often than recorded. The rarity lies not necessarily in the behaviour itself, but in capturing it with reliable data.
M637’s journey demonstrates how large predators can move across complex, human-dominated landscapes without being detected.
Wolves Can Swim—But Rarely Need To
While wolves are not aquatic animals, they are capable swimmers. In certain regions, such as coastal Canada, wolves have been observed swimming long distances between islands.
A report by National Geographic described “sea wolves” capable of swimming several miles, with some journeys reaching up to 7.5 miles (12 kilometers).
What makes this event notable is the context. The swim occurred not in remote wilderness, but in a populated European setting where lakes are surrounded by settlements and infrastructure.
The Broader Context: Wolves Returning to Switzerland
This event occurs at a time when wolf populations are re-establishing themselves across Switzerland. According to the KORA Foundation, there were 43 confirmed packs during the 2025–2026 monitoring period, with 152 pups recorded.
Wolves began naturally returning to Switzerland in 1996 after being absent for nearly a century. The first confirmed pack appeared in 2012 in the Calanda region, and the population has steadily grown since.
This resurgence has led to ongoing discussions around livestock protection, wildlife management, and coexistence strategies.
What Lies Ahead for M637
Recent updates from the KORA Foundation indicate that M637 continues to travel. As of March 25, 2026, the wolf had moved from the Lamoura region in France back into Switzerland, reaching the Entlebuch area.
Whether M637 will eventually settle and establish territory or continue roaming remains uncertain. However, one thing is clear: wolves are highly adaptable and capable of navigating even the most unexpected routes when faced with challenges.