Snow of Tomorrow | Night Ski Tours

It was dark, the moon was shining brightly, snow lay on the green meadow. When a ski tourer rounded the [...] corner at lightning speed.

With a good headlamp, you can beat the late sunrise and early sunset in winter and bathe the otherwise dark path or unlit piste in a little floodlight. The aim of the small utensil on your head is to illuminate the terrain perfectly so that you can recognize all obstacles and impassibilities at an early stage and also keep an eye on the further course of the trail. To meet all requirements, sports equipment manufacturers have come up with quite a few ideas: Minimum weight, high-performance rechargeable batteries with a burn time of 800 hours, light ranges of up to 300 m and light levels of up to 3,000 lumens (1). "Betty" is the world's brightest headlamp (if you believe the manufacturer). It emits a gigantic 5,400 lumens, illuminates a range of 360 m and has a maximum brightness of 320 lux (1). The manufacturer touts it as the absolute maximum of technology, with enough power to flood entire valleys with light.

For comparison:

A normal candle or tea light emits 10 lumens, a projector 800-2,000 lumens and halogen headlights in cars emit 55 watts, which corresponds to around 1,200-1,500 lumens. Xenon headlights produce 35 watts, which corresponds to 3,000 lumens. In living spaces in general, the lighting measures between 200 and 300 lux.

Even less bright headlamps can disturb animals. — Less bright headlamps can also disturb animals
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LH

The brighter the lamp, the greater the disruption

A tour portal stated: "Keep in mind that alpine tours at night place higher demands on mountaineers than tours in daylight." This was followed by the recommendation of a powerful headlamp with spare batteries. However, this also increases the demands on the local wildlife. High-power headlamps illuminate a very wide area very brightly and therefore cause disturbance far beyond the area used. Not only the immediate track, path or slope is illuminated, but also the areas next to it. Such as the safe undergrowth or sheltering groups of trees.

Many wild animals stay in their dens during the day and only venture out onto the open areas at dusk and in the dark. This is shown, for example, by a study with radio-tagged red deer in the Black Forest (Coppes et al., 2017. Human recreation affects spatio-temporal habitat use patterns in red deer (Cervus elaphus)). During the day, red deer remain in the forest, seek shelter in dense tree cover and only enter the areas that are heavily used by recreational users during the day after dark.

Many of our native wild animals such as foxes, red deer and roe deer or wild boar would generally be diurnal animals, but since many people are out and about during the day, they have changed their rhythm of life accordingly and shifted their activities, such as feeding and searching for mates, to the night. They avoid us humans not only in terms of space, but also in terms of time. Wild animals learn that recreational use mainly takes place during the day and therefore avoid areas near paths during the day, but not at night (Gaynor et al. 2018, Lesmerises et al. 2017, Westekemper et al. 2018). However, if the risk varies unpredictably over time, for example if recreational use occasionally occurs late in the evening after sunset or early in the morning before sunrise, this unpredictable, sudden and therefore difficult to assess disturbance is potentially perceived as a greater risk, resulting in a more pronounced response (Cromsigt et al. 2013, Gaynor et al. 2019, Lima & Bednekoff 1999)." (Peters et al., 2023, What effects do recreational activities have on wildlife behavior, physiology and demography? Results of a comparative literature study.)

If we now invade these off-peak times with our special equipment, the animals will be in real trouble. At dusk and dawn, the animals find the peace and quiet they need to eat the food they so urgently need to survive, especially during the winter months. The bright and wide beam of light from the high-tech headlamps causes a large disturbance radius and forces the animals to remain in cover or even flee deeper into the protective forest. This deprives them of important phases for food intake and energy production. Even worse: the energy is used up by a strenuous escape in the snow.

Reality check: ski tours in Tyrol in open terrain

There is a wide range of night-time activities on offer, but what is the real situation with ski tours in open terrain in Tyrol?

Since winter 2014/15, the state of Tyrol has been operating a measurement network for monitoring outdoor sports as part of the "Bergwelt Tirol - Miteinander Erleben" program. Girsberger avalanche transceiver checkpoints are used for the measurements. The frequencies are recorded with the date and time using the integrated avalanche transceiver sensor, which detects passing ski mountaineers who have activated their avalanche transceiver (ski mountaineers who have not activated their avalanche transceiver are counted using an IR sensor. However, this signal was not analyzed for the purpose of this question). In total, the data from 33 measuring stations with 337,453 signals could be evaluated. (Assumption: the signals are detected both on the ascent and descent of the ski tours. The total number of ski tours thus amounts to 168,727 (=337,453 / 2)).

A cozy evening in a hut instead of a twilight ski tour: more relaxed for people and animals. — A cozy evening in a hut instead of a twilight ski tour: more relaxed for people and animals
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LH

For the statistics, the "sunrise hour" (30 min before and 30 min after sunrise) is counted as hour 0. The proportion of signals received up to hour 0 is 19,105, which means that 19,105 tours were started up to hour 0. This is based on the assumption that ascents are made in darkness and descents in daylight. The counts before sunrise are therefore not halved (like the total number of tours) because there is one radio signal before sunrise per tourer. The second radio signal on the descent comes later and is therefore not relevant for the observed period.

From the sunset hour (30 min before and 30 min after sunset), the proportion of received signals (= tours) is 5,932. At sunrise, therefore, there was about three times as much walking/skiing as at sunset.

Figure 3 below in the image gallery shows that a total of 7.42% of ski tours in the morning or evening extend into the twilight period. The focus is clearly on the morning hours. The early start to spring ski tours is understandable for safety reasons and due to the better snow quality in the morning, but nevertheless overlaps with the early morning activity of wild animals.

However, the almost 2% that are on the trail in the evening twilight and end up in the night are questionable both for safety reasons and from an ecological point of view. Depending on the snow conditions, weather and fitness of the animals, these few disturbances can have a serious impact on the (survival) of the individual.

Nature, and animals in particular, need spatial and temporal niches into which they can retreat without being disturbed. If you want to help avoid disturbing wild animals too much in winter, you should avoid tours in open terrain at dusk and at night. If you want to keep fit outdoors and set off in the dark with a clear conscience, we recommend using the specially approved piste tours in the nearby ski area.

1) Lumen (Latin for light) is the emitted power and, in simple terms, refers to the brightness of the headlamp. The light range indicates the maximum distance that a lamp can illuminate.

2) Lux (lat.) describes how much light falls on a surface. 1 lux means that an area of 1m² is evenly illuminated with 1 lumen.