Home Newsletter 2011 Brown Bear Monitoring in Bulgaria

by Kostadin Valchev

The activities of the LIFE EX-TRA Project in Bulgaria aim to improve the public attitude towards bears and to make people aware of the main objectives of bear conservation dealing with the problems of biology, ecology and behavior well as human-bear conflict management. Collaboration with the different parties interested is of great importance for the success of this initiative. That is why the Balkani Wildlife Society is working closely with the Ministry of Environment and Water (also a partner of the LIFE EX-TRA Project) and its derived structures – Regional Inspectorate of Environment and Water – Smolian, Executive Agency of the Environment, Directorates of the three National parks – “Rila”, “Pirin” and “Central Balkan”, Executive Forest Agency (one of the organizations managing the bears) as well as many local communities located in the project area.

The Bulgarian brown bear population is divided in two sub-populations – Rilo-Rhodopean and Central Balkan, which have no confirmed connection with each other. One of the project actions is aimed at determining the number and the conditions of the species and also monitoring the development of the species. To do that the following techniques were applied:

  • Capture-mark-recapture (through DNA sampling) – over 334 samples have been collected up to now;
  • Transects – as part of the National System for Biodiversity Monitoring, altogether 53 transects were set up in working and surrounding areas;
  • Camera traps – set in Central Balkan NP, Rila NP, Pirin NP and in the adjusting areas as well as in the Smolyan region, altogether over 428 camera days;
  • GPS-GSM telemetry – 5 bears have been captured and collared with GPS-GSM transmitters in the frame of the project and there were 2 others before this.

 

Additional analysis was carried out with the help of questionnaires. All the information has been processed in a GIS that examines habitat suitability for the brown bear.

As a result of the application of these methods it can be stated that brown bears in Bulgaria are distributed over 10,500 square kilometres of the national territory (around 10%), which also includes areas outside the targeted project areas. The Bulgarian bear population is estimated at round 400-700 individuals.

The analysis of the collected telemetry data shows that the bears in the Central Balkan area have a smaller home range (65-120 km2) than the ones in the Rhodopi Mountains (over 300 km2). The Central Balkan area is covered mainly with beech forests, which have higher plant productivity, whereas the forests in the Rhodopi Mountains are mainly coniferous or mixed with the prevalence of coniferous species. This hypothesis is also supported by the frequent and extensive bear damage in the Smolyan region, Central Rhodopi Mountains.

According to the GIS model of habitat suitability conducted during the project, it is estimated that the Smolyan region can hold 101 mature or a total of 126 bears including sub-adults (bears that have not yet reached reproductive age). For the whole project area a preliminary estimate of the holding capacity is of 223 mature bears or a total of 278 including sub-adults.

A precise estimate of the number of individuals, the density and their trends cannot be made before the DNA results are analyzed and at least one more year of monitoring is conducted. Up to now 217 of the DNA-samples have been processed, of which 144 are good-quality bear samples (66,4 % success rate). The best results are obtained from tissue samples, with a 100% success rate. Sampling from scats, whose success rate is 85,5 % is less efficient. The estimate of the number of sampled bears, their sex and relationships are subject to further analysis.