Swiss Wolf M637 Stuns Wildlife Experts with Unprecedented Swim Across Lake Lucerne

A GPS-tracked wolf stunned researchers by swimming 1.5km across Lake Lucerne in 5°C water, the first documented case of its kind in Switzerland.

By: AXL Media

Published: Apr 18, 2026, 8:53 AM EDT

Source: Information for this report was sourced from Swissinfo and KORA.

A Rare Feat of Aquatic Endurance

In a discovery that has redefined the behavioral boundaries of large carnivores in Switzerland, a male wolf designated M637 has been confirmed to have swum across the expansive Lake Lucerne. Data analyzed by the KORA Foundation for Carnivore Ecology and Wildlife Management revealed that the animal opted for a direct water crossing rather than circumnavigating the shoreline. The crossing, which occurred on February 13, 2026, saw the wolf traverse approximately 1.5 kilometers of open water where temperatures were recorded at a frigid 5°C.

GPS Evidence Confirms the Crossing

The movement data was captured via a GPS collar fitted to the 3- to 4-year-old male in late October 2025 as part of the "Wolves and Cattle" research project. According to biologist Flurin Kunz, the tracking points placed the animal on both sides of the lake within a 90-minute window, a timeframe that rendered a terrestrial detour around the bays physically impossible. One specific ping was logged directly in the center of the lake, providing the first hard evidence of such a crossing in Swiss history.

Navigating the Cultural Landscape

Experts suggest that the decision to swim was likely a tactical choice to avoid human conflict. For a dispersing wolf, shorelines represent a gauntlet of roads, villages, and tourist infrastructure. By cutting across the lake, M637 successfully bypassed densely populated areas and transport corridors that often impede the movement of large predators. This "hidden behavior" highlights how wolves are learning to utilize the least-expected routes to navigate one of the most human-modified environments in Europe.