Abstract 25 – Brown bear occurrence along a proposed highway route in Romania’s Carpathian Mountains

Csaba Domokos, Sebastian Collet, Carsten Nowak, Ferenc Jánoska, Bogdan
Cristescu

Major road developments are planned or ongoing throughout the range of the Romanian
brown bear (Ursus arctos) population, which is numerically the largest in the European Union.
The planned A8 (Tîrgu Mureș–Iași–Ungheni) highway crosses the Romanian Eastern Carpathians
on their entire width, posing a risk to the Romanian and broader transfrontier Carpathian bear
population. In the summers of 2014, 2017 and 2020, we surveyed an 80 km-long section of the
planned highway using baited hair traps (n = 68 throughout all sessions, with three additional
traps active only in 2020) mounted in pairs along the route. We aimed to assess bear
occurrence, movement, and to estimate the minimum number and sex ratio of bears present in
the area. With an effort of 3,519 hair trapping days (17 days / trap / session), we identified 24
individuals from the collected hair samples (n = 45), with a higher prevalence of female bears
(male:female sex ratio of 1:1.3). We did not document individual bears crossing the planned
highway, but detected functional connectivity across the planned highway through parent-
offspring (4 cases), full-sib (2 cases) and half-sib (24 cases) genetic relationships among sampled
individuals. We analyzed habitat characteristics and human-related covariates associated with
hair trap locations to identify influences on bear presence and found that terrain ruggedness
and longitude were the most important predictors of bear occurrence. Bears consistently
occurred in rugged terrain in the Western part of the study area, and were often detected close
(< 1 km) to human settlements. Even before the construction of the A8 highway, connectivity is
likely already limited by the existing extensive network of settlements, being restricted to a few
important linkage areas still free of developments. Additional threats to bears and other wildlife
in the area include poaching and large numbers of free-ranging dogs. We provide
recommendations to mitigate these threats.