Hanja B Brandl

Max Planck Institute of Animal Behavior · Department of Collective Behaviour (Universität Konstanz)

The stress response helps individuals cope with challenges, yet how individual stress levels shape group-level processes and the behaviour of other group members has rarely been explored. In social groups, stress responses can be buffered by others or transmitted to members that have not even experienced the stressor first-hand. Stress transmission...

Research Highlight: Mistrick, J., Veitch, J. S. M., Kitchen, S. M., Clague, S., Newman, B. C., Hall, R. J., Budischak, S. A., Forbes, K. M., & Craft, M. E. (2024). Effects of food supplementation and helminth removal on space use and spatial overlap in wild rodent populations. Journal of Animal Ecology. http://doi.org/10.1111/1365‐2656.14067. The s...

Forming collectives can generate substantial benefits, but much less is known about the costs that individuals incur in doing so. We simultaneously captured individual movement, within-group position, leadership, and heart rate for each member in a group of wild vulturine guineafowl. Individuals had significantly increased heart rates when moving c...

As a result of a warming global climate, understanding how organisms adjust their behaviour to environmental thermal conditions has become an increasingly important question in animal biology. Temperature‐driven adjustments in parental care are potentially important given the repercussions on offspring size, quality and survival. In 2015 and 2016 w...

Major climatic changes in conjunction with animal movement may be associated with the spread of parasites and their vectors into new populations, with potentially important consequences for population persistence. Parasites can evolve to adapt to unsuitable ecological conditions and take up refuge within new host species, with consequences for the...

As a result of a warming global climate, understanding how organisms adjust their behaviour to environmental thermal conditions has become an increasingly important question in animal biology. Temperature-driven adjustments in parental care are potentially important due to their repercussions on offspring size, quality and survival. In 2015 and 201...

Parasites can impact the behavior of animals and alter the interplay with ecological factors in their environment. Studying the effects that parasites have on animals thus requires accurate estimates of infections in individuals. However, quantifying parasites can be challenging due to several factors. Laboratory techniques, physiological fluctuati...

The stress systems are powerful mediators between the organism's systemic dynamic equilibrium and changes in its environment beyond the level of anticipated fluctuations. Over- or under-activation of the stress systems' responses can impact an animal's health, survival and reproductive success. While physiological stress responses and their influen...

Background So far, large numbers of studies investigating the microbiome have focused on gut microbiota and less have addressed the microbiome of the skin. Especially in avian taxa our understanding of the ecology and function of these bacteria remains incomplete. The involvement of skin bacteria in intra-specific communication has recently receive...

The social decisions that individuals make—who to interact with and how frequently—give rise to social structure. The resulting social structure then determines how individuals interact with their surroundings—resources and risks, pathogens and predators, competitors and cooperators. However, despite intensive research on (a) how individuals make s...

Individual identification is a crucial step to answer many questions in evolutionary biology and is mostly performed by marking animals with tags. Such methods are well‐established, but often make data collection and analyses time‐consuming, or limit the contexts in which data can be collected. Recent computational advances, specifically deep learn...

Background: An animal’s skin is densely populated with a physiological community of bacteria that represents the first barrier to its environment. Investigations on the physiological skin flora have emerged in recent years, but especially in avian taxa our understanding of the ecology and function of these bacteria remains incomplete. The involveme...

Background: So far, large numbers of studies investigating the microbiome have focused on gut microbiota and less have addressed the microbiome of the skin. Especially in avian taxa our understanding of the ecology and function of these bacteria remains incomplete. The involvement of skin bacteria in intra-specific communication has recently receiv...

Background: So far, large numbers of studies investigating the microbiome have focused on gut microbiota and less have addressed the microbiome of the skin. Especially in avian taxa our understanding of the ecology and function of these bacteria remains incomplete. The involvement of skin bacteria in intra-specific communication has recently receiv...

Individual identification is a crucial step to answer many questions in evolutionary biology and is mostly performed by marking animals with tags. Such methods are well established but often make data collection and analyses time consuming and consequently are not suited for collecting very large datasets. Recent technological and analytical advanc...

Many animals live and breed in colonies, and yet, with just a few exceptions, the value of the social bonds between colony members has rarely been examined. Social ties are important for group coordination at collective tasks, and social coordination can facilitate synchronized reproduction among colony members. Synchronized reproduction in turn ca...

Animals time reproductive events to overlap with periods of favorable environmental conditions. However, weather conditions can be unpredictable. Young animals may be particularly susceptible to extreme weather during sensitive developmental periods. Here, we investigated the effects of adverse weather conditions on corticosterone levels (a hormone...

Social information can spread fast and help animals adapt in fluctuating environments. Prospecting on the breeding sites of others, a widespread behavior, can help to maximize reproduction by, for instance, settling in the same area as other successful breeders. Previous studies have shown that successful broods have the highest number of prospecto...

Organisms should aim to time their reproduction to match the optimal ecological conditions and thus maximize their fitness. However, social cues have been identified as determinants of reproductive decisions and might also be involved in coordinating the timing of reproduction. Breeding synchronously with other individuals can bring several advanta...

Sexually transmitted infections (STIs) in animals may have profound eco-evolutionary consequences, yet experimental studies of the sexual transmission of pathogens in wild populations are lacking. Here to identify sexually transmitted bacteria, we experimentally manipulated ejaculate transfer in black-legged kittiwakes (Rissa tridactyla) by blockin...

Early-life experience can fundamentally shape individual life-history trajectories. Previous research has suggested that exposure to stress during development causes differences in social behaviour later in life. In captivity, juvenile zebra finches exposed to elevated corticosterone levels were less socially choosy and more central in their social...

Information about the quality of local habitat can greatly help to improve an individual’s decision-making and, ultimately, its fitness. Nevertheless, little is known about the mechanisms and significance of information use in reproductive decisions, especially in unpredictable environments. We tested the hypothesis that perceived breeding success...

The Helmeted Woodpecker Dryocopus galeatus is a threatened species of the Atlantic Forest in southeastern South America. It has traditionally been placed in the genus Dryocopus, but it shows similarities in plumage and structure with woodpeckers in the genus Celeus. We sequenced mitochondrial and nuclear DNA that was sampled from live captured Helm...

Bacteria play a central role in animal health. Yet, little is known about the acquisition of bacteria and the extent to which bacteria are acquired from different environmental sources. For example, bird nests host diverse bacteria associated with the eggs, nestlings and nesting material, but previous research has typically focussed on only a limit...

Dendrobatidae (dart-poison frogs) exhibit some of the most complex spa-tial behaviors among amphibians, such as territoriality and tadpole trans-port from terrestrial clutches to widely distributed deposition sites. In species that exhibit long-term territoriality, high homing performance after tadpole transport can be assumed, but experimental evi...

Background Gastrointestinal bacteria play a central role in the health of animals. The bacteria that individuals acquire as they age may therefore have profound consequences for their future fitness. However, changes in microbial community structure with host age remain poorly understood. We characterised the cloacal bacteria assemblages of chicks...