Projects

We focus on the mechanisms and functions of social life, in greylag geese (Anser anser), ravens (Corvus corax), jackdaws (Corvus monedula) and northern bald ibis (or “Waldrapp ibis”, Geronticus eremita). Major topics are steroid hormones as mediators and markers of social behaviour as well as the role of cognitive mechanisms in social interactions and group living.

We are working with a semi-tame flock of geese, with a relatively stable group of wild ravens, keep ravens and jackdaws in aviaries, and do experimental projects with a free-flying colony of the critically endangered northern bald ibis. This is the first free-living group of bald ibises in Europe since 400 years. Thus, one of our foremost principles is to be aware of our specific "scientific niche", to utilize the benefits offered by our unique site and animals, but also to be aware of the constraints. Our work is clearly problem-orientated, but with a strong focus on intact groups in their natural environment.

Our work in geese and ravens and data from other labs increasingly show a surprising degree of convergence in social mechanisms and organization of birds and mammals. For example, greylags maintain long-term family bonds and via female attachment and form clan-like structures. Geese actively and passively support their partners, meaning that they aid them in aggressive interactions with others and their presence dampens stress responses of those involved in such interactions. A complex sociality is generally linked with formidable cognitive abilities. In that respect we are still at he beginning in geese. In corvids (ravens and jackdaws) however, cognition research is well under way. From what we know, we may, for example, conclude, that ravens are indeed, “flying apes”. Such a convergence between mammals and birds despite 320 million years of separate evolution may be a surprise. Still, it can be explained by common selection pressures acting on, and in, social systems and also, by the evolutionarily conservative vertebrate brain.

Another field of our work is the relationship between hormones and behaviour. Steroid hormones in particular, are major agents in behavioural and structural ontogeny. Androgens, estrogens, corticosteroids and other hormones are involved in the regulation of socio-sexual behaviour and in stress coping. Hormones influence behaviour, but vice versa, environmental and social stimuli feed back on the hormonal status of individuals. Individual differences are not random, but vary according to “personality”. In the greylag geese, we investigate how these hormones are modulated in the individuals by season, sex, age, social interactions, dominance, etc. Hormones are sampled non-invasively from faeces and other excretion products. This method has been developed and validated in close cooperation with Profs. Möstl and Palme from the Institute of Biochemistry, University of Veterinary Medicine (VUW), Vienna. Thereby, catching and handling of the animals can be avoided and corticosterone metabolites can be measured without interference by the sampling method. In addition, the faecal sample reveals an integrated hormone value over 1-3 hours.

In the geese, we have shown that social status significantly modulates the annual steroid patterns, that males respond to challenging situations and that the degree of testosterone-covariation over the year in the pairs may indicate pair-bond quality in these long-term monogamous animals (FWF-project P10483BIO; most relevant articles can be downloaded). We continued with a focus (FWF-project P12914BIO) at the influence of early exposure to steroids of maternal origin on personality development in birds. It is known, that the amount of maternal testosterone in the egg yolk makes a big difference concerning individual coping style in canaries, producing more or less bold individuals. These effects are lifelong and influence how individual's approach and deal with environmental and social stimuli. Here, Japanese quail are used as an additional model. This work is now continued by Dr. Aline Bertin from the University of Rennes, France, in collaboration with Dr. Katharina Hirschenhauser and Prof. Möstl and Prof. Palme at the Institute of Biochemistry, VUW. Dr. Bertin investigates how post-hatch mothering and pre-hatch maternal hormonal effects affect offspring behavioural development. Again in geese, we linked social behaviour, corticosterone excretion and heart rate with personality in the course of a FWF-funded project (P15766-B03), testing coping style theory and investigating the yearlong energetic effects (the costs and benefits) of social life as related to personalities.

In the Bald ibis, we investigated foraging and feeding in our free-flying group on the one hand and hormones and behaviour on the other. Excreted testosterone and corticosterone was measured in hand-raised sibling groups of different age composition. Equally aged nestmates grew significantly slower than those in the nests with natural age composition. Natural foraging and scrounging (taking away food found by others) was monitored. A study on the share of labour revealed that pair partners excrete near-equal amounts of testosterone in this ibis, which was followed by a study on the relationship between sexual ornaments and immunity.

Cognitive ethology deals with the question whether, how and why individuals and species differ in their cognitive abilities. Linked to our basic theme, social mechanisms, we are particularly interested in “social intelligence”. We first investigated the capacities of social learning in a hand-raised sibling group of ravens and then, by observation and experiments tackled the question, how wild ravens coordinate over food and snatch food from each other. Finally, we showed for the first time that birds are capable of “tactical deception”. In geese, we used experimental approaches to demonstrate, how, and along what social lines, traditions spread. In addition, detailed experimental work is done on mechanisms and social context of social learning in young and adult geese. Via the social contexts of social learning and their links with steroid hormones, the major two branches of our research, hormones and cognition now merge. We showed, for example, that the disposition to solve problems is linked with a certain personality. We now concentrate on aspects of social learning in both ravens and jackdaws, social knowledge and observational spatial memory, as well as the ability to use others' gaze.

A third focus, besides hormones and cognition, is to establish a local colony of Bald ibis. Today, wild populations of these birds in Morocco and Syria are down to 200. However, there are approx. 2000 in captivity, reproducing well. In Europe, this ibis went extinct 400 years ago. With establishing a free-living, resident group in Grünau, we aim at having another animal group at hand, 1) for basic research in social behaviour and 2) to gain know-how for reintroduction projects of this critically endangered species in suitable habitats in the wild. We started 1997. The first two years were difficult and we lost most of the birds to predators and due to dispersal in autumn. Today we have a free-flying group of approx. 40 birds in the valley, which finds its own food during spring and summer, and is never locked into the aviary in the Cumberland park any more, which is also its breeding site and night roost.

The group started reproducing as a breeding colony in 2002, when 4 young fledged. Our results indicate that a re-introduction of this ibis into Europe is possible, if also a new migratory tradition can be established (see www.waldrappteam.at). The hand raising of Bald ibis and other species creates also an experimental situation which offers controlled conditions for research. For example, we dealt with the influence of sibling age differences on aggressive interactions, stress and growth and investigated how single chicks grow and socialize within the colony in comparison with those who spent their first 3 weeks of life together with siblings. Studies on social complexity are underway.