Who skis where, when? – A method to enumerate backcountry usage

Backcountry skiers, travelling in avalanche terrain, account for a large proportion of avalanche fatalities worldwide. Despite this, the exact count of the number of recreationists exposed to avalanches (also known as the background information), is poorly documented in most countries. Without detailed background information on temporal and spatial backcountry usage, making well-reasoned decisions from fatality statistics is impossible. This study developed a methodology to enumerate a large proportion of backcountry usage from a 2589 km 2 study area in Tromsø, Northern Norway. We use an extensive network of specially adapted beacon checkers – small, waterproof devices that detect and count signals from avalanche transceivers. Over two seasons, from December to May from 2021 to 2023, we recorded 56,760 individual trips. Our findings indicate that most (60.0 %) backcountry trips begin between 07:00 and 12:00, with noticeable activity in the afternoon as well. Saturdays and Sundays see the highest daily activity rates, comprising 40.1 % of total weekly traffic, while weekdays, though less busy per day, account for the remaining 59.9 %. The peak season for winter backcountry skiing is during March and April (when counts from the period December to May are considered), accounting for 56.3 % of all traffic. This monthly usage aligns with avalanche incident data, where 55.8 % of incidents occur during the same two months. Our study demonstrates the use of our methodology and advances the understanding of temporal trends from winter backcountry skiing, quantifying the movement characteristics of backcountry skiers in Tromsø, Norway. • A method to enumerate winter backcountry skiers in Tromsø, Norway. • A novel approach using an extensive network of beacon checkers. • We estimate 56,760 individual trips over two winter seasons from 2021 to 2023. • Most activity in March and April aligns with incident data.