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Predation risk, stress and life history tactics in the edible dormouse

Abstract
The exact timing of producing offspring is an important factor for an animal’s lifetime reproductive success. In seasonal environments reproduction is typically linked to the spring and summer season, when food availability is high. However, not all food resources are that easy to predict. Various terrestrial ecosystems are characterised by “pulsed resources”, i.e., occasional, short periods of resource superabundance. The edible dormouse (Glis glis), a small, arboreal hibernator, shows several remarkable adaptations to fluctuations in seed production of trees, and life-history characteristics related to pulsed resource exploitation. Dormice litter only once per year in July/ August, which is extremely late in the active season, compared to other hibernators. Reproduction just in time with the availability of ripe, high-caloric seeds on tree branches apparently optimizes survival and pre-hibernation fattening of their young. The disadvantage of this highly specialized adaptation is that in years without beechnuts or acorns the survival of juveniles would be very low. Hence, dormice skip reproduction in years without seed production.It seems that the availability of energy-rich food (seed buds) in spring represents an environmental signal to which dormice adjust their reproduction. At present, it is entirely unclear, however, by which pathway this signal translates into reproductive success or failure. Here, we propose to test the hypothesis that effects of food quality on reproduction in dormice are linked to a factor that has never been considered before in this context, their exposure to predation pressure. Specifically, we hypothesize that access to energy-rich food (in years of mast seeding) allows the animals to minimize foraging time and hence exposure to predators, which can be a major stressor. We suggest that dormice are an excellent model to study the ‘Chronic Stress Hypothesis’ which predicts that the stress profile of an animal, and its physiological consequences, result from simultaneous effects of both food requirements and predation pressures, caused by the trade-off between the need to forage and to avoid predators. We therefore plan to measure the time spent foraging (via transponder systems) and the concentration of faecal cortisol metabolites in a dormouse population in the Vienna Woods.For dormice, which forage in the canopy of woods, the major predators are nocturnal birds of prey, namely owls. One possible avenue of evading these predators altogether – at least in years of reproduction skipping – would be evasion by retreat into underground burrows. Due to the combination of estivation and hibernation, dormice can spend up to > 10 months per year in dormancy. Thus, they spend much more time in hypometabolism than climatic conditions or food resources would demand. These results led us to hypothesize that the primary cause for estivation is not reduction of energy expenditure but predator avoidance. We plan to record body temperature in free-ranging dormice during summer seasons under different environmental conditions. In a supplemental feeding field experiment we plan to investigate the effect of seed availability on the occurrence of estivation, the daily time spent foraging, concentration of cortisol metabolites, and reproduction. Further, we will investigate the consequences of the combination of hibernation, estivation, and reproduction skipping on life history characteristics of dormice, specifically on ageing.
Statistik Austria science classification
106026         Ecosystem research
106047         Animal ecology
106048         Animal physiology
Lemma
Life-History-Taktiken Siebenschläfer
Project leader
Ruf Thomas
Duration
01.01.13-31.12.16
Type of Research
Basic research
Staff
Stalder G., Project team member
Vetmed Research Units
Research Institute of Wildlife Ecology
Funded by
FWF - Fonds zur Förderung der wissenschaftlichen Forschung, Sensengasse 1, 1090 Wien, Austria

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11 Publications

Ruf, T; Bieber, C (2020): Physiological, Behavioral, and Life-History Adaptations to Environmental Fluctuations in the Edible Dormouse. Front Physiol. 2020; 11:423
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Ruf, T; Bieber, C (2020): Use of social thermoregulation fluctuates with mast seeding and reproduction in a pulsed resource consumer. Oecologia. 2020; 192(4):919-928
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Nowack, J; Tarmann, I; Hoelzl, F; Smith, S; Giroud, S; Ruf, T (2019): Always a price to pay: hibernation at low temperatures comes with a trade-off between energy savings and telomere damage. Biol Lett. 2019; 15(10):20190466

Weber, K; Hoelzl, F; Cornils, JS; Smith, S; Bieber, C; Balint, B; Ruf, T (2018): Multiple paternity in a population of free-living edible dormice (Glis glis). Mammalian Biology 2018; 93: 45-50
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Cornils, JS; Hoelzl, F; Huber, N; Zink, R; Gerritsmann, H; Bieber, C; Schwarzenberger, F; Ruf, T (2018): The insensitive dormouse: reproduction skipping is not caused by chronic stress in Glis glis . J Exp Biol. 2018; 221(Pt 20):

Cornils, JS; Hoelzl, F; Rotter, B; Bieber, C; Ruf, T (2017): Edible dormice (Glis glis) avoid areas with a high density of their preferred food plant - the European beech. Front Zool. 2017; 14:23
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Bieber, C; Cornils, JS; Hoelzl, F; Giroud, S; Ruf, T (2017): The costs of locomotor activity? Maximum body temperatures and the use of torpor during the active season in edible dormice. J Comp Physiol B. 2017; 187(5-6):803-814
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Hoelzl, F; Smith, S; Cornils, JS; Aydinonat, D; Bieber, C; Ruf, T (2016): Telomeres are elongated in older individuals in a hibernating rodent, the edible dormouse (Glis glis). Sci Rep. 2016; 6:36856
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Hoelzl, F; Bieber, C; Cornils, JS; Gerritsmann, H; Stalder, GL; Walzer, C; Ruf, T (2015): How to spend the summer? Free-living dormice (Glis glis) can hibernate for 11 months in non-reproductive years. J Comp Physiol B. 2015; 185(8):931-939
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Ruf, T; Geiser, F (2015): Daily torpor and hibernation in birds and mammals. Biol Rev Camb Philos Soc. 2015; 90(3):891-926
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Bieber, C; Lebl, K; Stalder, G; Geiser, F; Ruf, T (2014): Body mass dependent use of hibernation: why not prolong the active season, if they can. Funct Ecol (28), 1 167-177.
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