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ŠUMARSKI LIST 11-12/2021 str. 20     <-- 20 -->        PDF

the management of protected wild species, where the goal of monitoring is to determine the efficacy of conservation actions (Breitenmoser et al. 2006). Monitoring objectives must be clearly defined to decide which indicators should be monitored and which methods should be used. Basic monitoring involves collecting data on the distribution, abundance and density of the population and their changes over time. This serves as a foundation for efficient population management (Thompson et al. 1998).
The Eurasian lynx (Lynx lynx) is protected in Croatia by the Ordinance on declaring protected and strictly protected wildlife species (Official Gazette No 144/13, 73/16) and it is listed as critically endangered (CR) on the IUCN Red List of Threatened Species. Habitats Directive (92/43/EEC) lists Eurasian lynx on Annexes II and IV, requiring strict protection and population monitoring. For the Habitat Directive reporting period 2013-2017, the conservation status of the lynx population in the Alpine region in Croatia was evaluated as unfavorable - bad (U2), while the situation in the Continental and Mediterranean region was assessed as unfavorable - inadequate (U1) (Anonymous 2019). The loss of genetic diversity is considered as the most important threat to lynx in Croatia, as the entire Dinaric population originated from six reintroduced animals (Sindičić et al. 2013). Decrease in population size was also invigorated by high human – induced mortality (Sindičić et al. 2016), while lack of appropriate management indirectly influenced the unfavorable status of lynx population in Croatia (Sindičić et al. 2019).
With the development of technology, photo traps became the most effective and cost-efficient methodology for monitoring lynx population (Rovero and Zimmerman 2016). In Croatia first lynx monitoring activities using automatic cameras (camera traps) were conducted in Gorski Kotar in the 2011 – 2014 period (Kusak 2012; Kusak and Modrić 2012; Kusak et al. 2013, Kusak et al. 2014),while wide – scale population monitoring with camera traps is in place since 2018 within the project LIFE16 NAT/SI/000634 “Preventing the Extinction of the Dinaric-SE Alpine Lynx Population through Reinforcement and Long-term Conservation” (acronym LIFE Lynx) (Sindičić et al. 2018).
In this paper, we present results of the lynx population monitoring in Croatia for the period 2018 - 2020. The goal of the monitoring was to determine the lynx distribution area and to estimate the minimum size of the lynx population in Croatia.
Signs of lynx presence were collected for two years, from 1st of May 2018 until 30th of April 2020. This period overlaps with two “lynx years” defined as period from the beginning of May to end of April, since kittens are mostly born in May and leave the mother in April of the following year (Zimmerman et al. 2005). All available observations from all possible sources, including photos, mortality, sightings, lynx prey, footprints and samples collected for DNA analysis (feces, urine, hair) were archived in Faculty of Veterinary Medicine University of Zagreb database (Gomerčić 2017), which is publicly available on the internet address Each sign of lynx presence was registered with information about location and time, provider of the information and was categorized according to SCALP criteria (Breitenmoser et al. 2006):
Collected data was mapped using program QGIS ( 2020). Lynx distribution was determined on a 10 x 10 km Pan-European grid (European Environmental Agency 2017), with permanent presence confirmed for quadrants in which lynx was recorded based on at least one C1 observation or two C2 observations. Quadrants with only one C2 observation were defined as areas of sporadic presence, while quadrants with only C3 observations were defined as areas of possible presence but without solid evidence (Kusak et al. 2016). Total surface of permanent, occasional and areas of possible lynx presence in Croatia were calculated by summing the surface of quadrants with predefined observations.
For the estimation of minimum population size a network of camera traps was set in Gorski kotar, Lika and northern Dalmatia - areas previously defined as lynx distribution area in Croatia (Sindičić et al. 2010). Three additional camera traps were placed on Pelješac, as we wanted to check several undocumented reports of lynx sightings on the peninsula. For optimal camera trap placement, we used 10 x 10 km grid cells and a lynx sensitivity (presence probability) map produced by Kusak et al. (2016). At least one non-baited camera trap was placed within each 10 x 10 km grid cell, while cells that were categorized by Kusak et al. (2016) as unsuitable or low suitably for lynx were excluded from the research. To maximize lynx detectability camera traps were set at optimal locations within cells, where landscape and terrain features were likely to channel lynx movements, like lynx marking sites, forest roads and game paths. Those locations were identified based on previously archived observations of lynx presence and with the help of local hunters and rangers. Different brands and models of camera traps with active infrared sensor and infrared flash were used, set to capture one photo and 30 seconds of video or three photos without the video. During the period May 2018 - April 2020, camera traps were set at 182 locations. Although camera traps were intended to stay at each location all year round, due to malfunctions, theft and snow coverage some of them were not active during the entire research period on the selected location. We checked camera traps at least