Habitat at the mountain tops: how long can Rock Ptarmigan (Lagopus muta helvetica) survive rapid climate change in the Swiss Alps? A multi-scale approach

Abstract

Ongoing monitoring in the Swiss Alps has shown that Rock Ptarmigan (Lagopus muta helvetica) has suffered a significant population decrease over the last decade and climate change has been proposed as a potential cause. In this study, we investigate the response of this high alpine grouse species to rapid climate change. We address a problem often neglected in macro-ecological studies on species distribution: scale-dependency of distribution models. The models are based on empirical field data and on environmental databases for large-scale models. The implementation of several statistical modelling approaches, external validation strategies and the implementation of a recent study on regional climate change in Switzerland ensure robust predictions of future range shifts. Our results demonstrate that, on the territory level, variables depicting vegetation, heterogeneity of local topography and habitat structure have greatest explanatory power. In contrast at the meso-scale and macro-scale (with grain sizes of 1 and 100 km 2 , respectively), bioclimatic and land cover-related variables play a prominent role. The models predict that, based on increasing temperatures during the breeding season, potential habitat will decrease by up to two-thirds until the year 2070. At the same time, a shift of potential habitat towards the mountain tops is predicted. The multiscale approach highlights the true extent of potential habitat for this species with its patchy distribution in steep terrain. The small-scale analysis pinpoints the key habitat areas within the extensive areas of suitable habitat predicted by models on large grain sizes and in this way reveals sub-grid variability. Our results can facilitate the adaptation of species conservation strategies to a quickly changing environment. ZusammenfassungHabitat auf den Gipfeln der Berge: Wie lange kann das Alpenschneehuhn (Lagopus muta helvetica) raschen Klimawandel in den Schweizer Alpen ü berleben? Ein mehrskaliger Ansatz.Fortlaufendes Monitoring hat gezeigt, dass innerhalb des letzten Jahrzehnts die Population des Alpenschneehuhns (Lagopus muta helvetica) in den Schweizer Alpen stark abgenommen hat. Als mögliche Ursache kommt der Klimawandel in Betracht. In dieser Studie untersuchen wir die Auswirkungen raschen Klimawandels auf dieses hochalpine Raufußhuhn. Dabei setzten wir uns mit einem Aspekt auseinander, der in vielen makroökologischen Studien oft vernachlässigt wird: die Skalenabhängigkeit von Habitatmodellen. Die Modelle basieren auf empirischen Felddaten und auf Umweltdatenbanken für die Communicated by T. Gottschalk.

Pyrenean ptarmigans decline under climatic and human influences through the Holocene

“…According to recent studies (Revermann et al, 2012) and the predictions of Météo-France (Nogués-Bravo et al, 2007;Nogués-Bravo et al, 2008), we can expect, in the near future, a further upward shift of the Pyrenean tree line and consequently an upward shift of the suitable habitat of the rock ptarmigan. However, the future tree line position is challenging to predict in the Pyrenees as increasing temperature may also induce more frequent summer droughts, negatively affecting the tree line dynamics by reducing growth and seedling viability (Batllori and Gutiérrez, 2008).…”

Managing Protected Areas in Central and Eastern Europe Under Climate Change

“…The proportion of chicks in August depends on the onset of snow melt, mean minimal and maximal air temperatures during spring and early summer (Novoa et al 2008). In all the species distribution models, the mean July temperature, annual precipitation, July water budget and July cloud cover were found to be the most powerful bioclimate variables for determining the distribution patterns of rock ptarmigan (Revermann et al 2012). Furthermore, the powerful influence of the mean July temperature on rock ptarmigan distribution was stressed by Revermann et al (2012) in connection with the heat dissipation limit theory (Speakman and Król 2010).…”

“…In all the species distribution models, the mean July temperature, annual precipitation, July water budget and July cloud cover were found to be the most powerful bioclimate variables for determining the distribution patterns of rock ptarmigan (Revermann et al 2012). Furthermore, the powerful influence of the mean July temperature on rock ptarmigan distribution was stressed by Revermann et al (2012) in connection with the heat dissipation limit theory (Speakman and Król 2010). Following this theory, we can explain the appearance of endothermic animals, including rock ptarmigan, in areas with lower temperatures in an attempt to avoid hyperthermia.…”

“…In contrast to the central distributional area of rock ptarmigan where the species still occupies most of the original range, some local declines in relatively small populations in Alps and Pyrenees, on the southern border of its distribution area, have been noted (Novoa et al 2008;Revermann et al 2012;Storch 2007). In some studies, based on the effect of climate on the rock ptarmigan and its related whitetailed ptarmigan (Lagopus leucurus), climate change has been recognised as one of the major factors influencing the population dynamics of these species (e.g.…”

“…In some studies, based on the effect of climate on the rock ptarmigan and its related whitetailed ptarmigan (Lagopus leucurus), climate change has been recognised as one of the major factors influencing the population dynamics of these species (e.g. Revermann et al 2012;Wang et al 2002). Nevertheless, human influences, specially uncontrolled tourism (ski-resorts, recreation activities) still remains the most important impacts on the rock ptarmigan population in the Alps and Pyrenees (Storch 2007).…”