How do hyenas survive

Behavioral ecology and evolutionary biology of the spotted hyena population of the Ngorongoro crater: How (well) does a group-living predator adapt to social and ecological changes?

How - and how well - do group-living animals react to social and ecological changes? In order to answer this question, we examine the evolution of social behavior as well as behavioral and evolutionary processes that shape 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 observed since 1996 and for which we have created an almost complete genetic tree over nine generations.

Running time:Since 04/1996
Third-party funded:Yes
Participating department (s):Dept. Evolutionary Ecology, Dept. Evolutionary Genetics, Dept. Wildlife Diseases, Dept. Reproductive Biology, Dept. Ecological Dynamics
Project management in the Leibniz-IZW:Oliver Höner (Department of Evolutionary Ecology)
Project participants in the Leibniz-IZW: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. Reproductive Biology), Sarah Benhaiem (Dept. Ecological Dynamics)
Consortium partner:Université de Montpellier, ISEM, CNRS (France), Australian National University (Australia), Technical University Berlin, Friedrich Loeffler Institute, Wageningen University (Netherlands), Tanzania People & Wildlife (Tanzania), Tanzania Wildlife Research Institute (Tanzania), Ngorongoro Conservation Area Authority (Tanzania), American Express (USA)
Current funding organization:German Research Foundation (DFG), German Academic Exchange Service (DAAD), Werner Dessauer Foundation
Research focus:Understanding of characteristics and evolutionary adaptations
Understanding of wildlife health and disturbed homeostasis
Understanding wildlife challenges
Improving the viability of wildlife populations
Development of new theories, methods and tools

 

We investigate how - and how well - group living animals react to changes in their social and ecological environment. We concentrate on five main topics: (i) the evolution of social behavior and behavioral and evolutionary processes that shape the life history and fitness of group living animals; these include partner choice, sexual conflicts, reproductive tactics, social dominance, cultural evolution, emigration; (ii) the costs and benefits of group living to assess how well social systems of group animals adapt to change; (iii) the interplay between social environment, behavior, physiology and fitness; (iv) the interplay between changes in demographic and genetic characteristics of a population; (v) the coexistence of humans and large predators.

Our research system for researching these topics is ideal. We have been observing the entire population of spotted hyenas (eight social groups, more than 2500 individuals) in the Ngorongoro Crater in Tanzania since 1996. We have collected land time data on the behavior, life history, physiology, health, diet, survival and reproductive success of these hyenas and created an almost complete genetic pedigree over nine generations. This comprehensive empirical data set and an individual simulation model based on our knowledge of the hyena system offer us unique opportunities to investigate evolutionary and applied questions on all three levels - individual, social group, population.

Research topic 1: The evolution of social behavior and social and ecological processes in animals living in groups

Spotted hyenas live in large social groups of up to 130 animals. They show complex social behavior similar to that of primates and humans, and they live in societies that are structured by dominance relationships. As with other social species, social rank has a huge impact on a hyena's performance and fitness. We investigate how rank-related characteristics and privileges are transferred to the next generation and how dominance hierarchies and inter- and intrasexual dominance form and develop. We also investigate what causes changes in the social environment (e.g. social rank, gender ratio, relationship, coalition partner) and how the social environment influences the behavior, reproductive tactics, life history and fitness of an individual. In collaboration with international colleagues, we have identified important fitness-related mechanisms and decision-making rules (e.g. choice of partner, choice of reproductive group, social support) and investigate how these mechanisms and rules complex social, cultural, ecological and evolutionary processes and patterns at the group level (e.g. social hierarchy and differences in reproductive success) and the population (e.g. gender-specific migration, gene flow).

Research topic 2: Costs and benefits of group life and the survival of populations of group animals

The life of a low-ranking member of a group can be very different from that of a high-ranking member. We examine the costs and benefits of living in hierarchically structured societies and the intrinsic and ecological factors that influence individual fitness as well as demographics and group survival. We also study how populations of species living in groups react to social, demographic and ecological changes. Since pathogens are an important driver of evolutionary processes and influence the survival of individuals, groups and populations, we document the health of hyenas. In collaboration with the Department of Wildlife Diseases, we are researching the effects of pathogen infections on hyenas' health and fitness, as well as the epidemiology and long-term effects of disease outbreaks in group animals.

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

Knowledge of the physiological basis of behavior and life histories and of the adaptability of physiological control systems to environmental changes is the key to understanding the effects of the social environment and human-made changes on the animal world. We investigate the causes and consequences of different allostatic stress and the interplay between allostatic stress, behavior, investment in reproduction and fitness in group living animals. To this end, we have been measuring the hormone concentrations of the Ngorongoro hyenas since 1996 in cooperation with the endocrinology laboratory of the Department of Reproductive Biology and combine this data with our long-term data on the behavior, life history and reproductive success of the hyenas. We use a method that we have developed in cooperation with the departments for Reproductive Biology and Ecological Dynamics and that allows hormone measurements to be compared over long periods of time and between different laboratories.

Research Topic 4: Simulating the Hyena Society to Investigate Evolutionary Issues and Wildlife Conservation

Understanding the interplay between changes in demographic and genetic characteristics of a population is important in order to be able to assess how populations and species develop and how they react to changes in their environment. The two causes of change are linked and run through complex feedback loops. In cooperation with the Department of Evolutionary Genetics, we are designing an individual 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 study a wide range of fundamental evolutionary questions as well as questions that have practical implications for the conservation of social, group living species.

Research topic 5: Human-predator interactions and conflicts

Large predators are often in conflict with ranchers because of attacks on livestock and humans. Our study area is a UNESCO World Heritage Site, where Maasai herders and several species of large predators (lion, spotted hyena, striped hyena, wild dog, cheetah, leopard) have lived side by side for generations. In cooperation with local stakeholders, international colleagues and the departments for evolutionary genetics and reproductive biology, we apply ecological, genetic and social science methods to study the coexistence of humans and predators and to defuse conflicts between humans and predators.

Learn more about this project at https://de-ngorongoro.hyena-project.com/.

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.