Ao. Univ.-Prof. Dr. Eva Millesi

Eva Millesi

Head of Department
Department of Behavioural Biology
Faculty of Life Sciences
University of Vienna
Althanstraße 14 (UZA I)
1090 Vienna

T +43 (1) 4277-544 65
F +43 (1) 4277-545 06

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Effects of reproductive behavior and physiology on hibernation in small mammals

Hibernators have to adjust reproductive activity to seasonal constraints by keeping an annual schedule, allowing enough time for the preparation for the hibernation phase. Nevertheless, a relatively high variation in seasonal timing reflects different strategies to maximize reproductive output in a limited time period.
We investigated two model species representing obligate and facultative hibernators. The European ground squirrel (Spermophilus citellus) shows a very constant annual cycle, females produce only one litter per season and both adults and juveniles accumulate body fat reserves to survive in their hibernacula. The Common hamster (Cricetus cricetus), on the other hand, is known for its more facultative overwintering strategy. Reproductive output is highly variable among individual females ranging from 0-3 litters per season. In contrast to the ground squirrels, Common hamsters can use both body fat as internal and food caches as external energy reserves. In both species however, the timing of vernal emergence and mating can be crucial for reproductive success.
In European ground squirrels an intriguing phenomenon has been documented. The females enter a second oestrus cycle including an active luteal phase after having weaned their offspring in June. In this time of the year, males have already terminated sexual activity. The non-reproductive oestrus cycle with its endocrine output appears to have positive effects on both prehibernatory fattening and reproduction in the subsequent season.
In Common hamsters, previous maternal effort seems to affect the preparation for hibernation and accordingly overwinter behaviour.

Curriculum Vitae


1969-81: School education, Vienna

1981-1989: Student at the University of Vienna (Biology, main subject Zoology)

1989: PhD graduation

2001: Habilitation, University of Vienna


Since June 2009: Head of the Department of Behavioural Biology

2007-2009: Deputy head, Department of Behavioural Biology, Faculty of Life Sciences, University of Vienna

2001: Associate professor at the Institute for Zoology, Department of Ethology, University of Vienna

1997: Postdoctoral training at the MPI for Behavioral Physiology, Seewiesen, Germany

1994-2000: Research assistant at the Department of Ethology, Institute for Zoology, University of Vienna

1993: Postdoctoral training at the Institute for Zoology, Department of Ethology, University of Vienna and the University of Groningen, The Netherlands

1991-1993: Research assistant funded by the Austrian Science Foundation (FWF)

1990-1991: Postdoc research scholarship, University of Vienna

Research interests

The emphasis of the current research programs is on interactions among hibernation, reproductive behaviour and physiology in facultative and obligate hibernators. Critical developmental phases, the consistency of individual reproductive strategies and consequences of parental investment are analysed and related to over-winter behaviour and physiology. A second  focus is on effects of hibernation on cognitive functions, like memory retention.

Another research field is based on social relationships and stress management. We investigate effects of social bonds on basal adrenal activity in birds and mammals and mechanisms of reproductive suppression in canid and primate species.

A recently started research focus is represented by the Emerging Field "Social Systems" (Faculty of Life Sciences, heads Eva Millesi and Thomas Bugnyar). In this topic, researches from different departments and institutions within and outside the faculty aim to integrate their specific expertise to investigate aspects of social dynamics in animal and human societies. The species studied range from eusocial insects to fish, birds, and mammals including non-human primates and humans. Diet composition during ontogeny seems to play a major role in neural development that may affect cognitive abilities, social status and predisposition for aggressive behaviour in adulthood.

We have initiated three research projects in 2010 involving the University of Vienna (Departments Behavioral Biology, Nutritional Sciences, Anthropology, Cognitive Biology), the Medical University of Vienna and the University of Veterinary Medicine Vienna.

Research Grants

  • FWF P8337-BIO: Effects of physiological and ecological constraints on the reproductive biology of European ground squirrels
  • Austrian Nationalbank PNr. 6590: Effects of hibernation on memory in European ground squirrels
  • Austrian Nationalbank PNr. 7450: Maternal investment in relation to litter size and sex ratio in ground squirrels
  • FWF (Austrian Science Fund) P13646-BIO: Factors affecting follicular development in European ground squirrels
  • FWF P160001-B06: Reproductive strategies of female European hamsters
  • Austrian Academy of Sciences: Seasonal effects on reproduction in Common hamsters
  • FWF P16968-B12: Factors affecting puberty in male European ground squirrels
  • University of Vienna, Intrafaculty Project Proposal: Effects of polyunsaturated fatty acids on cognition, physiological stress modulation, offspring sex ratio, and social behavior in Guinea pigs
  • FWF P24280-B20:  Effects of internal and external energy reserves on hibernation in Common hamsters



  • Introduction to Animal Behaviour
  • Methods in Behavioural Sciences
  • Mammalogy
  • Reproductive Strategies in Vertebrates
  • Behavioural Ecology

Practical Courses

  • Animal Behaviour - Introductory experiments in Animal Behaviour
  • Animal Physiology Laboratory 1 - Reproduction, Metabolism and Immunology Practical Course in Animal Behaviour
  • Practical Course in Behavioural Physiology
  • Training Course in Ethology


  • Behavioural Ecology Seminar (with Michael Taborsky, University of Bern)
  • Seminar for Masters, Diploma and PhD-students in Animal Behaviour

Other Professional Activities

Scientific Society Memberships

  • International Ethological Society (council member)
  • DGS (German Society for Mammalian Biology)
  • ASAB (Association for the Study of Animal Behaviour)


Animal Behaviour, Canadian Journal of Zoology, Ethology, Hormones and Behavior, Journal of Comparative Physiology A, Journal of Mammalogy, Lutra, Mammalian Biology, Physiology and Behavior

  • Mentoring Program for Women Academics and Scientists at the University of Vienna (Mentor)
  • Biology Study Programme: committee member
  • Radiation safety officer: radionuclide laboratory UZA1, Micro CT (Micro XCT Transmission X-ray Microscope, Dept. Theoretical Biology), MicroCT (Viscom X8060-25, Dept. Anthropology)
  • Animal ethics commissioner: International Ethological Society
  • Contributions to the “Action plan for Common hamster conservation“, Austrian League for Nature Conservation
  • Vienna City Administration (MA22, MA42), Scientific advisor (conservation and management plans for European ground squirrels and Common hamsters

Relevant publications

Franceschini-Zink, C., Millesi, E. (2008). Reproductive performance in female Common hamsters. Zoology 111, 76-83.

Franceschini, C., Siutz, C., Palme, R., Millesi, E. (2007). Seasonal changes in cortisol and progesterone secretion in Common hamsters. Gen. Comp. Endocrinol. 152, 14-21.

Huber, S., Millesi, E., Dittami, J.P. (2002). Paternal effort and its relation to mating success in the European ground squirrel. Anim. Behav. 63, 157-164.

Hufnagl, S., Franceschini-Zink, C., Millesi, E. (2011). Seasonal constraints and reproductive performance in female Common hamsters (Cricetus cricetus). Mamm. Biol. 76, 124-128.

Millesi, E., Strauss, A., Burger, T., Hoffmann, I.E., Walzl, M. (2008). Follicular development in European ground squirrels in different phases of the annual cycle. Reproduction 136, 205-210.

Strauss A., Hoffmann I.E., Walzl, M., Millesi E. (2009). Vaginal oestrus during the reproductive and non-reproductive period in European ground squirrels. Anim. Reprod. Sci.  112, 362-370.

Strauss A., Mascher E., Palme R., Millesi E. (2007). Sexually mature and immature yearling male European ground squirrels: a comparison of behavioral and physiological parameters. Horm. Behav. 52, 646-652.