Climate change has prompted three of the most common ungulate species in the Alps – chamois, ibex and red deer – to move to higher elevations in the late summer and autumn. The tendency of roe deer to move to higher ground was weaker.
Fig. 1 - Over
the past two decades, Grisons chamois have moved their retreats to
higher elevations. Click to enlarge.
Photo: Thomas Wehrli (Amt für Jagd und Fischerei GR)
In recent decades, researchers have documented numerous examples of animal and plant species moving to higher elevations due to climate change. This also applies to three alpine ungulate species, as an international research team led by the Swiss Federal Research Institute WSL showed on the basis of a unique data set. The Canton of Grisons Hunting and Fishing Authority documented more than 230,000 places in the canton where roe deer, red deer, chamois and ibex were harvested between 1991 and 2013.
Analysis of these data shows that ibex, chamois and red deer frequented significantly higher ground during this time, elevations that are, on average, 135, 95 and 80 metres respectively higher than those they previously frequented. "This data set is unique and shows that even large, warm-blooded species react to rising ambient temperatures", says Kurt Bollmann from WSL's Conservation Biology research group. Previously, it had been assumed that this behaviour applies in particular to plants and cold-blooded animals, such as reptiles or insects.
Ungulate behaviour depends on the environmental conditions during the hunting season and varies from year to year. If the autumn is warm and snow-free, then the sites where red deer, chamois and ibex are shot are at higher elevations. These are species that mainly feed on pastures and alpine grasslands. Roe deer are more closely linked to their territories and to the forest, so their tendency to move to higher ground was weaker.
Over the last 20 years, mean September and October temperatures in the area covered by the study have risen by 1.3°C, a trend which, climate models predict is set to continue. This will change the supply, accessibility and quality of plant food in the mountain forests and Alpine grasslands, which will force wild animals to further adjust their food intake in keeping with the higher elevations they frequent.
The results so far indicate that red deer, chamois and ibex in the Canton of Grisons are reacting
flexibly to this change. Whether or not this may
have longer-term consequences for the populations of the investigated ungulates cannot be concluded
with any certainty today. "However, consistent, precise and continuous
documentation of harvesting sites is an important and valuable basis for future
research on the impact of climate change on large game species", says
co-author Hannes Jenny from Grisosn Hunting and Fishing Authority.
Fig. 2 - Spatial distribution of 230,565 ungulates that were harvested in the
eastern Swiss canton Grisons, between 280 and 3600 m asl, and during the
1991–2013 period. Click to enlarge.
|Fig. 3 - Differences in harvest elevation classes calculated for the early (1981–2002) and late (2002–2013) split periods for each species. The shift to higher grounds is clearly visible. Click to enlarge.|