Population size and effective population size are important factors affecting probability of extinction of small, isolated population. Hence, from conservation perspective, it is recommended to monitor changes in population size of endangered species. Genetic methods, based on genetic profiling of non-invasive samples of biological material, despite some limitations, were proved to be efficient method in tracking individuals in the field and estimate populations' parameters. We used this strategy to investigate isolated population of the capercaillie (Tetrao urogallus) in the Gorce Mountains. In two study periods (2012–2013 and 2017–2018) almost 400 faeces and feathers were collected. Microsatellite genotyping was performed to identify individuals and estimate genetic diversity. We found that population is stable in terms of size and genetic indices, although allelic richness has significantly increased between 2012–2013 and 2017–2018. In the overall study period (2012–2018) there were 52 individuals identified. However, only 10 birds were found in both study periods. This suggests low survival in the population. Moreover, genetic data indicated low effective population size of the capercaillie in the Gorce Mts. Thus, we suggest that monitoring, either genetic and based on field-surveys, should be implemented in the management and protection of this population.

Sex ratio (ratio between the number of male and female individuals in a population) is an important factor contributing to the survival rates of the population in wild. Imbalanced sex ratio is often the cause of diminished survival rates of endangered species. The analysis of DNA collected through noninvasive methodologies effectively allows to monitor populations of rare species or species that are difficult to observe in the wild. Such method was used to determine the sex ratio in populations of the capercaillie (Tetrao urogallus) and black grouse (Lyrurus tetrix) in the Tatra National Park. We collected over 250 samples (mostly excrement) in the area of the Tatra National Park and identified species via microsatellite genotyping and determined the sex using fragments of the CHD gene. We found that the majority of the samples belonged to male specimens irrespective of the species suggesting a large deviation from an equal sex ratio in wild populations of capercaillie and black grouse in the Tatra National Park. Our results point out the fundamental contribution of genetic assessment of sex ration to monitor the viability of both species in the Tatra National Park.

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