03.07.2023: How does climate change impact animals that hibernate? A team of researchers from the University of Veterinary Medicine Vienna looked into this question using an experimental set-up. The study revealed that garden dormice (Eliomys quercinus) are quite capable of adapting to warmer climatic conditions – provided that enough food is available.

Torpor, including hibernation, is an energy-saving strategy used by many animals during the cold season. Climate change impacts this period of reduced metabolic rate and body temperature by increasing the frequency of periodic rewarming, which is characterised by high levels of oxidative stress and is associated with a shortening of the telomeres – the protective caps at the ends of the chromosomes that become shorter with each cell division and are essentially responsible for ageing.

Aim of the study: to investigate feeding behaviour and telomere dynamics during hibernation

Against this background, the researchers investigated the impact of ambient temperature on feeding behaviour and telomere dynamics in garden dormice. This small nocturnal mammal prepares for hibernation by accumulating fat reserves but also eats during hibernation. Food intake, torpor pattern, changes in telomere length, and body mass change were measured in animals kept at experimentally controlled temperatures of either 14 °C (a mild winter) or 3 °C (a cold winter) over a period of six months.

Higher temperatures interfere with hibernation; animals compensate through increased food intake

When hibernating at 14 °C, garden dormice experienced 1.7-fold more frequent and 2.4-fold longer periods of arousal compared to animals hibernating at 3 °C. “Higher food intake enabled individuals to compensate for increased energetic costs when hibernating at milder temperatures, to buffer body mass loss and so increase winter survival,” explains co-first author Marie-Therese Ragger from the Research Institute of Wildlife Ecology at Vetmeduni.

Telomeres significantly elongated regardless of temperature

Interestingly, the researchers observed a significant increase in telomere length over the entire hibernation period, regardless of temperature. According to study co-first author Sylvain Giroud (Research Institute of Wildlife Ecology at Vetmeduni), the research team therefore concludes that “even higher temperatures during winter, if associated with sufficient food availability, can have a positive effect on the individual’s energy balance and somatic maintenance. These results suggest that winter food availability might be a crucial determinant for the survival of the garden dormouse in the context of ever-increasing environmental temperatures.”

The article “Food availability positively affects the survival and somatic maintenance of hibernating garden dormice (Eliomys quercinus)” by Sylvain Giroud, Marie-Therese Ragger, Amélie Baille, Franz Hölzl, Steve Smith, Julia Nowack and Thomas Ruf was published in Frontiers in Zoology.

Scientific article