How the ‘humanisation’ of the environment affects brown bears

As with all wildlife, and perhaps even more so, brown bears are affected by loss of living space and changes to the remaining parts of habitat. This has led to the extinction of bears in most parts of Western Europe. Poland, Croatia and Sweden still have bears in parts of the countries.

Djuro Huber

Bears have to cope with an environment that is being changed by human activities. Some examples include the development of buildings and transport infrastructure into bear habitats, the growing number of tourists in natural areas, the increased supply of human foods that are accessible to bears (e.g. garbage), corn fields or food provided in the forest to feed wildlife for hunting, as well as higher levels of pollution. All these might have an effect on bears and their health. In this project, we investigate how the ‘humanisation’ of the environment affects the health of brown bear populations. In order to do this, we are measuring several parameters indicative of health condition in the hair, scats, bones and tissue of brown bears from Poland, Croatia and Sweden. These samples have been obtained from data banks and scientific collections in the research institutions of the three countries collaborating in this project. They are complemented with samples collected in the field in a non-invasive way.

The COVID-19 pandemic affected our project considerably: field work was not possible and, even more importantly, the laboratories in 4 countries that were conducting various analyses of our samples all closed in March 2020, so the final project results will also be delayed. On the other hand, the rise in importance of the coronavirus drew additional attention to what we have been doing already for three years before the COVID-19 outbreak. Dr Vladimir Stevanovic at the Faculty of Veterinary Medicine in Zagreb and other Croatian collaborators have been routinely checking the exposure of brown bears in Croatia to a longer list of viral (and other) pathogens. This included alfa-coronavirus, which affects the intestinal tract. Around 300 bear samples were tested, and all were negative. We intend to test recent bear samples for beta-coronavirus also (where SARS-CoV-2 belongs). However, that will be possible only after the pandemic stops.

This study is paving the way for additional standards in brown bear and other wildlife research. When tracking stress, food assimilation and flow of pathogens become the routine procedure, risky changes in the environment could be detected early enough to apply proper conservation measures. Science will have a powerful and standardized tool for monitoring ecosystem stability. The results of this research will represent a contribution in that direction and may reveal brown bears as sentinels of detrimental changes in the environment.

How did you benefit from the POLONEZ fellowship?

The study of brown bear ecology and, in particular, the status and health of bear populations has been my main research line for 40 years, and here it has been merged with the work of the Polish research team. We have established a unique research network in order to develop a wildlife health index to assess population status in a novel way. My daily joint work and scientific discussions with researchers at the Institute of Nature Conservation in Kraków has been a continuous bi-directional flow of knowledge transfer plus the real pleasure of being part of that. Now we have trained teams in both laboratory and field techniques, established standards for long-term data collection and analyses, as well as international cooperation through consolidated research network.

I will personally continue to work on the promotion of the approaches designed here to monitor brown bear populations and to implement such methods in conservation and management plans in other countries. The integrative character of this research is to also apply those results in further education at all levels: the general public, wildlife managers, university students. All of this I see as a significant personal benefit.


Prof. Djuro Huber was born in Zagreb, Croatia, in 1950. After graduating in veterinary medicine in 1975, he specialized in ecology (Master’s degree) and in wildlife parasitology (PhD in 1979). He has worked for 45 years at the Biology Department of the Faculty of Veterinary Medicine, University of Zagreb. In 1979/80 he attended the Wild Animal Disease Centre in Fort Collins, Colorado, USA on a Fulbright grant. Since 1981 he has been conducting a brown bear study in Croatia, which in 1996 expanded to the Study of large carnivores in Croatia (including bear, wolf and lynx). The research included radio-telemetry, with many morphological, physiological, nutritional and genetic aspects all supported by over 20 international projects and published in about 200 scientific papers. Djuro Huber is currently professor emeritus at the Department of Biology at the Veterinary Faculty in Zagreb.