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Contact

University of Bern
Institute of Ecology and Evolution
Baltzerstrasse 6
3012 Bern

Tel +41 (0)31 631 3010
Fax +41 (0)31 631 1234
michael.griesser@iee.unibe.ch

Office Location
D 104

Present Time
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Research

Evolution of Families and Group Living

My research tries to understand why family living in birds evolves, and how individuals interact with each other in groups. Using large set of European bird species, we focus on the link between life-history, ecological factors and family living (together with Emeline Mourocq and Gretchen Wagner, in collaboration with Alberto Redondo, Manolo Soler, Shinichi Nakagawa and Rita Covas). The detailed behavioural mechanisms of family living are addressed in Siberian Jays (in collaboration with Jan Ekman), while we use Brown Thornbills to understand the links between nest-predation and social decisions (together with Nicole Schneider and in collaboration with Erik Wapstra). I research the influence of individual quality on reproductive investment and the life-history consequences thereof using Siberian jays (in collaboration with Joanna Sendecka, Jan Ekman and Vivian Goerlich) as well as Great tits (in collaboration with Simone Webber and Jim Reynolds). For a more general understanding of group-living, we look at the mathematical and behavioural processes of grouping decisions in House Sparrows (in collaboration with David Sumpter and Qi Ma). 

1) Link between life-history and family living
Research has traditionally focused on the factors that facilitate cooperative breeding while the factors that lead to family living have been overlooked. Family living among birds is widespread and shows a lot of time independent offspring remain with their parents. We take advantage of this variation to understand the role of ecology and life-history for the evolution of family living using both field experiments and comparative studies.

2) Behavioural Mechanisms
With the help of field experiments in Siberian Jays, I look at the behavioural mechanisms that facilitate the formation of family groups in birds. I could show that jay parents use a large array of antipredator behaviours to increase the survival of their offspring. In particular, jays evolved a rich vocabulary which allows them to communicate predator category, risk and above all the behaviour of their main predators (hawks). By removing fathers from groups, we demonstrated that the presence of both parents is crucial for offspring to delay dispersal, since only the presence of both parents prevents unrelated dominants from joining the group and force offspring to leave the natal territory.

3) Nest Predation and Social Decisions
Using Brown Thornbills, a small Australian passerine, we look at the link between nest predation and social decisions outside the breeding season. Nest predation in most southern hemisphere species is rampant, affecting the reproductive decision of individuals and thus as well the social decisions outside the breeding season.

4) Life-history consequences of parental investment
Life-history theory predicts a strong link between the investment in current reproductive investment and investment in survival. We use field experiments in Siberian jays and Great tits to elucidate the effect of individual quality on this trade-off.

5) Mathematical and Behavioural Processes of Group Formation
One of the most striking aspects of animal groups is their remarkable variation in size, both within and between species. While a number of mechanistic models have been proposed to explain this variation, we only vaguely understand how environmental factors and behavioural activities affect group-size distributions. We use field observations, experiments and mathematical modelling to understand what drives group size in House Sparrows. 

Publications