Project AnthroBear PAN.BFB.S.BDN.617.022.2021: “Assessing population-level consequences of anthropogenic pressure: long-term stress and reproduction indices in brown bear populations in a gradient of human disturbances” has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 847639 and from the Ministry of Education and Science, within the frames of PASIFIC program, and is hosted by the Institute of Nature Conservation of Polish Academy of Sciences in Krakow.

Project duration: 01.03.2022 to 28.02.2024

Nearly all of Europe was home to brown bears around 500 years ago. Since then, escalating anthropogenic activities, including habitat loss, fragmentation, degradation, and warming climate led to severe range contractions. As a result, the brown bear population either declined or disappeared in many regions. In recent decades, brown bear populations have increased in Europe, returning to areas where they were once extinct. However, their habitat in Europe is now altered by growing urbanization (e.g., buildings, roads). In this project, we will study the impact of anthropogenic activities on stress and reproduction of brown bears. For that, we will measure several parameters indicative of stress and reproductive condition in the hair and tissues of brown bears obtained from Croatia and Poland.

Project goals

  • To reveal the histophysiology of adrenal glands and gonads in free-ranging brown bears in relation to stress and reproductive hormones concentrations in the hairs and tissues

Research show that exposure to escalating chronic anthropogenic stress factors can enlarge the adrenal glands size and increase its mass, which further can alter the magnitude of stress response. As a result of altered adrenal gland morphology and physiology, the overall physiological health, especially metabolism and reproductive fitness can be negatively compromised. Additionally, both the adrenal glands and reproductive glands undergo circannual changes, but exactly how adrenal glands modulate the histophysiology of reproductive glands in brown bear is not understood. Our goal is to investigate seasonal changes in the morphology and histophysiology of adrenal and reproductive glands and how adrenal glands can modulate the histophysiology of reproductive glands in different seasons. This will be achieved through histological, ultrastructural, and immunohistochemical analyses, as well as hormone concentration measurement in these tissues. The results will be then related to hair hormone concentrations of sampled individuals. This part of the study can help us to understand the reproductive potential and fitness of the brown bear in relation to altered adrenal gland physiology and will also serve as fundamental knowledge in interpretation of the data and results gathered to realize the second objective.

  • To investigate the impact of human settlements and anthropogenic activities on the physiological stress and reproductive hormones indices in free-ranging brown bear

Physiological stress refers to organism’s adaptive response to disturbances or stimuli. Initially, physiological changes induced by stress have an adaptive role and aim to maintain homeostasis (short- term, acute stress); however, a sustained increase in allostatic load (long-term, chronic stress) is associated with deleterious consequences to health and fitness and may decrease animal’s ability to cope with additional stressors. Previous research shows that human activities, such as outdoor recreation, tourism, hunting or habitat fragmentation affect wildlife stress levels and this can, in turn, affect not only individual health and fitness, but also population performance. Here, our goal is to assess whether and how human activities affect stress levels and reproductive indices in different time scales in the studied individuals and populations, as well as the potential consequences for their health and conservation status. To achieve this, we will use biomarkers of chronic stress that have been recently developed thanks to the successful implementation of endocrinology methods in wildlife research. Long–term stress and reproductive hormones will be measured by the concentration of cortisol, testosterone and progesterone in hairs. The results will be then related to anthropogenic pressure correlates in the study areas.

This project will develop a complementary approach to assess the basic vital physiological phenomenon and physiological responses to escalating anthropogenic activities. It will constitute a reference that may additionally inspire further research and be used in other species. This project will also provide valuable insights into long-term implications of altered physiological responses in management and conservations strategies.