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Dead Bears as a Monitoring Tool

With the elusive and sparsely distributed species as brown bears, each monitoring method is time and money consuming, and in most cases provides incomplete results. One way to mitigate those limitations is to collect each bit of data available. Large amount of data can be obtained from the bodies of dead animals. It is true that those are not any more part of the population in concern, but comprehensive approach will allow drawing useful and important conclusions on the state and the trend of the entire population. The first necessary step is to prepare the legal framework and build the human capacity to get the information of each bear death case, which must include the unique ID of the body, the exact date and time, location, the cause of death and the basic information about the animal (sex, age, and at least some body measurements). Next key action is collecting samples. The best option is to have a professional and trained team to visit such a site or to organize the transfer of the body to the qualified institution for full autopsy. The alternative is that local wildlife managers (typically hunters) do get some training, written protocol and tools to collect and store the samples. The list of samples depends on the state (freshness) of the body. The very minimum includes any piece of tissue for genetic studies (e.g. for genetic diversity and effective population size), the premolar tooth for aging and a hair sample (e.g. for stable isotopes to reveal the diet and for stress and/or reproductive hormones). The full list of samples includes pieces of nearly all organs and tissues: muscle (including diaphragm and heart), bone, fat, intestine (including content), liver, spleen, kidney, adrenal gland, lungs, brain, testicles or ovaries with uterus. Those can be checked for living pathogens (parasites, bacteria, viruses, and fungi), various potential toxicants (heavy metals, pesticides, radionuclides) and even immunological status. The very cause of death is in majority of cases quite obvious like hunting or traffic collisions, in some cases only the autopsy reveals it, or it remains undetermined. In any case the knowledge of the distribution of the causes of deaths and the trend of each type of casualty can be used as a powerful management tool. When combined with the results of analyses of all samples showing eventual pathology which did not cause the death itself, the managers will have a well backed picture of the population health, potential threats and quite clear directions for future management.

monitoring; brown bear; Ursus arctos; mortality

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