Stable body size of Alpine ungulates

Abstract

In many species, decreasing body size has been associated with increasing temperatures. Although climate-induced phenotypic shifts, and evolutionary impacts, can affect the structure and functioning of marine and terrestrial ecosystems through biological and metabolic rules, evidence for shrinking body size is often challenged by (i) relatively short intervals of observation, (ii) a limited number of individuals, and (iii) confinement to small and isolated populations. To overcome these issues and provide important multi-species, long-term information for conservation managers and scientists, we compiled and analysed 222 961 measurements of eviscerated body weight, 170 729 measurements of hind foot length and 145 980 measurements of lower jaw length, in the four most abundant Alpine ungulate species: ibex ( Capra ibex ), chamois ( Rupicapra rupicapra ), red deer ( Cervus elaphus ) and roe deer ( Capreolus capreolus ). Regardless of age, sex and phylogeny, the body mass and size of these sympatric animals, from the eastern Swiss Alps, remained stable between 1991 and 2013. Neither global warming nor local hunting influenced the fitness of the wild ungulates studied at a detectable level. However, we cannot rule out possible counteracting effects of enhanced nutritional resources associated with longer and warmer growing seasons, as well as the animals' ability to migrate along extensive elevational gradients in the highly diversified alpine landscape of this study.

Shrinking Alpine chamois: higher spring temperatures over the last 27 years in Switzerland are linked to a 3 kg reduction in body mass of yearlings

“…Our study adds to the previous research on the decrease in body mass in adults (data from this population and from Italy [ 19 ]) and yearlings (data from Italy [ 22 ] and Austria [ 23 ]). A recent study, however, did not find any change in body mass or size in chamois and three other ungulate species in the eastern Swiss Alps between 1991 and 2013 [ 24 ]. Several possible explanations are mentioned by the authors, including less extreme local changes in temperatures and forage quality in their population compared with other regions of the Alps.…”

“…Accordingly, most previous studies on the Alpine chamois have revealed a gradual shrinking in chamois body mass (e.g. [ 19 , 22 , 23 ], but see [ 24 ]). As observed previously by these studies, we expected a temporal decrease in the body mass of yearling chamois and a negative relationship with the temperature during spring–summer in the first two years of life (e.g.…”

Body size responses to the combined effects of climate and land use changes within an urban framework

“…For example, as temperate climates warm, growing seasons are also extended. Thus, some studies indicate that the negative effect of increased temperature on size is counteracted by the longer period of time during which animals can feed and grow (Büntgen et al, 2020; Chown & Jaco Klok, 2003; Davison & Field, 2017). However, extended growing seasons do not explain all observed variation in size changes over the past decades because the majority of size declines have been reported from temperate regions, indicating that longer growing seasons cannot counteract the negative impacts of warming in all cases.…”