Behavioural Ecology

We study behavioural interactions between individuals with regard to the ecological influences.

In particular we study the function and mechanism of chemical communication, the impact of skin bacteria on body odour, the function of preen oil of birds, behavioural adjustment to human-induced environmental changes, causes and consequences of individual variation in gut microbiome and niche choice and nice conformance. Our study species are mainly vertebrates like passerines (Taeniopygia guttata, Parus major, Cyanistes caeruleus, Charadriidae), salamander (Salamandra salamandra), bats (Saccopteryx bilineata) and different lizzard species. 

Avian olfaction

Birds can smell!

Despite the fact that songbirds have for a long time been thought to be anosmic, i.e. unable to perceive smells, more and more evidence accumulates that songbirds do not only have a sense of smell and use extrinsic odour cues for orientation, foraging and nest construction, but also make use of intrinsic cues for social communication.

Within our group we explore in which circumstances birds use their sense of smell and what kind of information is encoded in body odours. For example, zebra finches are able to perceive and react to olfactory cues. Adult females prefer the odour of their own nest during the nestling phase of their chicks but do not show a preference once their juveniles have fledged. Zebra finch fledglings are able to distinguish their own nest from a foreign nest using olfactory cues alone and are also able to recognise the nest of their genetic origin.

We do not only work on zebra finches, but also on other estridild finches, on great tits and blue tits and on plovers.

Recent publications
- Nestling odour modulates behavioural response in male, but not in female zebra finches - read more here
- Chemical analysis reveals sex differences in the preen gland secretion of breeding Blue Tits - read more here

Research group members
Barbara Caspers, Öncü Maraci, Kathrin Engel

Contact person
Barbara Caspers

What is the function of the preen oil of birds?

Birds have a specialized gland (preen gland or uropygial gland) which secretes a waxy mixture: preen oil. When birds preen, they collect preen oil from the gland and spread it on their plumage. Preen oil has many functions, including plumage maintenance, waterproofing or protection against parasites. Interestingly, preen oil is thought to be the main source of odour in birds, and may therefore play a role in chemical communication. By analysing the chemical composition of preen oil, we aim to decode the chemical cues emitted by birds.

In our lab, we analyse the chemical composition of the preen oil of several species (plovers, pied flycatchers, blue tits, zebra finches). We investigate the potential role of preen oil chemicals and avian odours in the breeding ecology of these species.

Recent publications
- Olfactory camouflage and communication in birds - read more here

Research group members
Marc Gilles, Barbara Caspers

Contact person
Marc Gilles

Animal-microbe interactions

Animal bodies harbour complex and dynamic microbial ecosystems, collectively known as microbiota. The discoveries in the last two decades have shed a light on the breadth of the relationships between microbial symbionts and their animal hosts, fundamentally altering our understanding of animal biology. Today it is well-established that microbial symbionts functionally involve in countless physiological processes and adaptations of their hosts. One of the most remarkable breakthroughs of microbiome research is the elucidation of the reciprocal interactions between animal-associated microorganisms and animal behaviour.

In a broad sense, we aim to understand the causes and consequences of individual-specific microbiomes. Our research primarily focuses on how environmental and host factors interact together to shape individual-specific microbial colonies (skin and gut) in birds, mammals, amphibians, and reptiles. We are also studying how individual variation in microbial communities translates into cognitive and behavioural differences and how they influence the olfactory profile and communicative behaviour of their hosts.

Recent publications
- The Gut Microbial Composition Is Species-Specific and Individual-Specific in Two Species of Estrildid Finches, the Bengalese Finch and the Zebra Finch - read more here
- Alterations to the Gut Microbiota of a Wild Juvenile Passerine in an Urban Mosaic - read more here
- Considering birds to understand the interplay of MHC, microbiota, and odor: a comment on Schubert et al. - read more here
- Family matters: skin microbiome reflects the social group and spatial proximity in wild zebra finches - read more here

Research group members
Öncü Maraci, Kathrin Engel, Meike Pust

Contact person
Öncü Maraci

What’s special about urban lizards?

Our research group is also working on understanding what makes urban animals so special. We are exploring the behaviour and cognition of different lacertid lizards from Croatia – genus Podarcis, Lacerta, and Dalmatolacerta. Part of the species in study can inhabit urban areas while other species are only found in rural or wild areas. This makes them perfect models to help us answer a fundamental question: How can some species cope with cities and live near humans, but others lack such ability? In specific, we are studying lizards’ cognitive and social skills, as well as their personality. Understanding how animals deal with changing anthropogenic environments is key to successfully manage conservation efforts in an era where urbanization and human population rates keep increasing.

Recent publications
- Invasive lizard has fewer parasites than native congener - read more here
- Playing dead: lizards show tonic immobility without human handling - read more here

Research group members
Isabel Damas Moreira, Avery Maune

Contact person
Isabel Damas Moreira

Niche choice and niche conformance

Individual niches change over lifetime due to developmental, social or environmental changes. This is especially noticeable in species, in which developmental changes, such as metamorphosis, require the conformation to different niches during ontogeny. The fire salamander (Salamandra salamandra) with its biphasic life cycle, switches its habitat from exclusively aquatic to terrestrial once metamorphosed. In addition to the niche change after metamorphosis, adult female fire salamanders of our study population in the Kottenforst (Bonn, Germany) can choose between two different larval deposition habitats: stream and pond.
We focus on niche conformance in fire salamander larvae in investigating e.g. their performance in their natural habitat and a transferred habitat (match-mismatch). In adult fire salamander we focus on niche choice of female fire salamanders. We are investigating for instance the factors that influence the choice for the larval deposition habitat and we are conducting personality tests.

Recent publications
- Individualised niches: an integrative conceptual framework across behaviour, ecology, and evolution - read more here
- The ravages of time - Life-long consequences of early larval nutritional conditions on the terrestrial life of fire salamanders (Salamandra salamandra) - read more here
- There is no place like home: Larval habitat type and size affect risk-taking behaviour in fire salamander larvae (Salamandra salamandra) - read more here
- Developmental costs of yellow colouration in fire salamanders and experiments to test the efficiency of yellow as a warning colouration - read more here
- Behavioural responses to chemical cues of predators differ between fire salamander larvae from two different habitats - read more here

Research group members
Max Mühlenhaupt, Pia Oswald, Laura Schulte, Barbara Caspers

Contact person
Max Mühlenhaupt
Laura Schulte

Our fire salamander research is part of the Collaborative Research Centre - Niche Choice, Niche Conformance, Niche Construction (NC3). Read more here.

Large carnivore ecology in Croatia

Interactions of predators and their prey are resulting in a complex behavioural response of both groups. In Europe`s terrestrial ecosystems large carnivores like grey wolves (Canis lupus) and Eurasian lynx (Lynx lynx) constitute apex predators. Ungulates, in particular roe deer (Capreolus capreolus), red deer (Cervus elaphus) and wild boar (Sus scrofa) are their main prey. The presence of large carnivores is causing lethal as well as non-lethal effects on herbivores populations. Interactions within this predator-prey system lead to fundamental processes influencing a hole ecosystem.

A worldwide growing impact of human presence on the natural world is also influencing predator-prey systems. In collaboration with the University of Zagreb, our research group is exploring the impacts of anthropogenic disturbance on interactions between wolves and lynx and their prey in different forest ecosystems of Croatia.

Research group members
Michael Schulte, Barbara Caspers

Contact person
Michael Schulte