Behavioural ecology and evolutionary biology of the spotted hyena population in the Ngorongoro Crater: How (well) does a group-living carnivore adapt to social and environmental change?

How – and how well – do group-living animals respond to social and environmental change? To address this question, we study the evolution of social behaviour and behavioural and evolutionary processes shaping the life history and fitness of group-living animals using an entire population of wild spotted hyenas (eight groups, more than 2500 individuals) that we have been monitoring since 1996 and for which we compiled an almost complete genetic pedigree across nine generations.

Project details
Duration: since 04/1996
Third-party funded: yes
Involved Department(s): Dept Evolutionary Ecology, Dept Evolutionary Genetics, Dept Wildlife Diseases, Dept Reproduction BiologyDept Ecological Dynamics
Leibniz-IZW Project Leader(s): Oliver Höner (Dept Evolutionary Ecology)
Leibniz-IZW Project Team: Eve Davidian, Arjun Dheer, Bettina Wachter, Zimai Li (all: Dept Evolutionary Ecology), Alexandre Courtiol, Colin Vullioud, Camila Mazzoni, Renita Danabalan (all: Dept Evolutionary Genetics), Liam Bailey (Dept Evolutionary Ecology + Dept Evolutionary Genetics), Gudrun Wibbelt, Kristin Mühldorfer (all: Dept Wildlife Diseases), Jella Wauters (Dept Reproduction Biology), Sarah Benhaiem (Dept Ecological Dynamics)
Consortium Partner(s): Université de Montpellier, ISEM, CNRS (France), Australian National University (Australia), Technische Universität Berlin, Friedrich-Loeffler-Institut, Wageningen University (The Netherlands), Tanzania People & Wildlife (Tanzania), Tanzania Wildlife Research Institute (Tanzania), Ngorongoro Conservation Area Authority (Tanzania), American Express (USA)
Current Funding Organisation: German Science Foundation (DFG), German Academic Exchange Service (DAAD), Werner Dessauer Foundation
Research Foci: Understanding traits and evolutionary adaptations
Understanding wildlife health and disturbed homeostasis
Understanding the environmental context
Improving population viability
Developing theories, methods, and tools


We study how – and how well – group-living animals respond to changes in their social and ecological environment. We currently focus on five main topics: (i) the evolution of social behaviour and behavioural and evolutionary processes shaping the life history and fitness of group-living animals; these include mate choice, sexual conflict, reproductive tactics, social dominance, cultural inheritance, dispersal; (ii) the costs and benefits of living in groups to assess how well social systems of group-living animals adapt to changes; (iii) the interplay between the social environment, behaviour, physiology and fitness; (iv) the interplay between changes in the demographic and genetic characteristics of a population; (v) the coexistence of humans and large carnivores.

Our study system is ideal to explore these topics. We have been monitoring the entire population of spotted hyenas (eight social groups, more than 2500 individuals) in the Ngorongoro Crater, Tanzania, since 1996. We have been collecting data on the behaviour, life history, physiology, health, diet, survival and reproductive success of these hyenas and compiled an almost complete genetic pedigree across nine generations. This comprehensive empirical dataset and an individual-based simulation model based on our knowledge of the hyena system provides us with unique opportunities to address evolutionary and applied questions at the level of the individual, the social group, and the population.

Research topic 1: The evolution of social behaviour and social and ecological processes in group-living animals

Spotted hyenas live in large social groups of up to 130 individuals. They express complex social behaviours similar to primates and humans and live in societies structured by dominance relationships. As in other social species, social rank has a major influence on the performance and fitness of an individual. We study how rank-related traits and benefits are transferred to the next generation and how dominance hierarchies and inter- and intrasexual dominance evolve. We also study what causes fluctuations in the social environment (e.g., social rank, sex-ratio, kinship, coalition partners) and how the social environment shapes an individual’s behaviour, reproductive tactic, life history and fitness. In collaboration with international colleagues, we identified key fitness-related mechanisms and decision rules (e.g., of mate choice, breeding-group choice, social support) and study how these drive complex social, cultural, ecological and evolutionary processes and patterns at the group (e.g., social hierarchy and reproductive skew) and population level (e.g., sex-biased dispersal, gene flow).

Research topic 2: The costs and benefits of group living and the viability of populations of group-living animals

Life in a group can be very different if you are a low-ranking or a high-ranking member of the group. We study the costs and benefits of life in hierarchically structured societies, the intrinsic and environmental factors that drive individual fitness and group demography and performance, and how populations of group-living species respond to social, demographic and environmental change using our long-term spotted hyena dataset. We also monitor the health of the hyenas and their infection with pathogens, a major driver of evolutionary processes that can threaten the survival of individuals, groups and populations. In collaboration with the Department of Wildlife Diseases, we study the impact of pathogen infection on the hyena’s health and fitness, and the epidemiology and long-term impact of disease outbreaks in group-living animals.

Research topic 3: The interplay between the social environment, physiological control mechanisms, and the behaviour and fitness of animals

Understanding the physiological underpinnings of behaviour and life histories and the flexibility of physiological control systems to environmental change are key to understanding the impact of the social environment and human-induced change on wildlife. We study the causes and consequences of variation in allostatic load and the interplay between allostatic load, behaviour, reproductive investment and fitness in group-living animals. For this, we have been monitoring the hormone concentrations of the Ngorongoro hyenas since 1996 in collaboration with the endocrine laboratory of the Department of Reproduction Biology and combine these data with our long-term data on the behaviour, life histories and reproductive success of the hyenas. We apply a method that we developed in collaboration with the Departments of Reproduction Biology and Ecological Dynamics which allows comparisons of hormone measurements over long time periods and between different laboratories, thereby facilitating long-term wildlife endocrinology research.

Research topic 4: Simulating the hyena society to study evolution and facilitate wildlife conservation

Understanding the interplay between changes in the demographic and genetic characteristics of a population is important to assess how populations and species evolve and how they respond to changes in their environment. Yet, the two sources of change are interconnected and undergo complex feedback loops. In collaboration with the Department of Evolutionary Genetics, we are designing an individual based simulation model of the spotted hyena society based on our long-term data on the Ngorongoro hyena population. This simulation model will allow us to address a wide range of both fundamental evolutionary questions and questions that have practical implications for the conservation of social, group-living species.

Research topic 5: Human-carnivore interactions and conflicts

Large carnivores are in conflict with pastoralists throughout the world because of depredation of livestock and attacks on humans. Our study site is a UNESCO World Heritage Site in which Maasai pastoralists and several species of large carnivores (lion, spotted hyena, striped hyena, wild dog, cheetah, leopard) have been living alongside each other for generations. In collaboration with local stakeholders, international colleagues, and the Departments of Evolutionary Genetics and Reproduction Biology, we apply ecological, genetic and social sciences methods to assess human-carnivore interactions and help mitigate human-carnivore conflict.


Learn more about this project at

Selected Publications

Vullioud C*, Davidian E*, Wachter B, Rousset F, Courtiol A**, Höner OP** (2019): Social support drives female dominance in the spotted hyaena. NAT ECOL EVOL 3, 71-76.

Davidian E, Courtiol A, Wachter B, Hofer H, Höner OP (2016): Why do some males choose to breed at home when most other males disperse? SCI ADV 2, e1501236.

Davidian E*, Benhaiem S*, Courtiol A, Hofer H, Höner OP, Dehnhard M (2015): Determining hormone metabolite concentrations when enzyme immunoassay accuracy varies over time. METHODS ECOL EVOL 6(5): 576-583.

Höner OP, Wachter B, Goller KV, Hofer H, Runyoro V, Thierer D, Fyumagwa RD, Müller T, East ML (2012): The impact of a pathogenic bacterium on a social carnivore population. J ANIM ECOL 81, 36-46.

Höner OP, Wachter B, Hofer H, Wilhelm K, Thierer D, Trillmich F, Burke T, East ML (2010): The fitness of dispersing spotted hyaena sons is influenced by maternal social status. NAT COMMUN 1, 60.

Höner OP, Wachter B, East ML, Streich WJ, Wilhelm K, Burke T, Hofer H (2007): Female mate-choice drives the evolution of male-biased dispersal in a social mammal. NATURE 448, 798-801.

Höner OP, Wachter B, East ML, Runyoro VA, Hofer H (2005): The effect of prey abundance and foraging tactics on the population dynamics of a social, territorial carnivore, the spotted hyena. OIKOS 108, 544-554.

Höner OP, Wachter B, Hofer H, East ML (2002): The response of spotted hyenas to long-term changes in prey populations: Functional response and interspecific kleptoparasitism. J ANIM ECOL 71, 236-246.