Endangered birds of old growth forests in the Pirin National Park, SW Bulgaria: habitat preferrences, distribution and population sizes in 2001-2019

A significant decline of 30.4% in the population of Tengmalm's Owls and Capercaillies was detected in Pirin National Park, Bulgaria, between 2001-2002 and 2019, alongside changes in their spatial distribution patterns. The study also recorded a very small population of Three-toed Woodpeckers (10–15 pairs) and the first breeding period documentation of Pygmy Owls in the park. Researchers used night line transects with acoustic playback for owls, daytime line transects for woodpeckers and Pygmy Owl, and tracking methods for Capercaillies, combined with GIS analysis to visualize habitat associations. The findings highlight threats such as ski tourism development, human disturbance, and sanitary cuttings, which could inform spatial planning efforts to protect these endangered species in the UNESCO World Heritage Site.

Shurulinkov, P., DASKALOVA, G., Ralev, A., TZVETKOV, P., VALCHEV, K., ARANGELOV, S., HRISTOV, I., KOLCHAGOV, R., & DIMOV, P. (2021). Endangered birds of old growth forests in the Pirin National Park, SW Bulgaria: habitat preferrences, distribution and population sizes in 2001-2019. Tichodroma, 33(1). https://doi.org/10.31577/tichodroma.2021.33.2