We studied the distributio of the Chapman's blue (Polyommatus thersites) in central Slovenia and its habitat choice was carried out in order to define conservation measures that will enable the long term survivour of this species in central Slovenia, but also wider in similar areas in Europe.
We found that the population of the Chapman's blue is stable in the surveyed area at gravels of the Sava River. From 17. 5. to 8. 6.2017, we conducted 17 fieldwork days in the survey area. During this time, we marked 152 specimens, of which 75 were males and 77 were females, with MRR method. The daily sizes of the population, estimated with the Jolly Seber method, ranged between 80 to 190 specimens. The numbers are unusual for this species as they normally occur in low densities in central Slovenia.
At the survey area were several separate habitats of The larval host plant sainfoin (Onobrychis spp.) was present in separate patches in the surveyed area and migrations among them was common. During the migrations, the specimens flew over the meadow areas and the dirt tracks. Chapman's blue was most often caught within host plant patches (77%), but several specimens were caught also outside them. The homerange of specimens caught more than once included larger part of the area included in the study.
According to our estimation, the habitat of the Chapman's Blue at the survey area is in relatively good condition, although illegal waste dumps and overgrowing with invasive plant species are present. It is important that the measures for improving the larval habitat are continued, as for example, with removal of invasive plant species. Also monitoring of the abundance of this endangered species with transect counts is still required. It is important to raise public awareness regarding the significant role of butterflies in the environment. Contribution to this could be done with the introduction of the nature tourism in the area of Sava gravels. Carefully planned activities related to butterflies could be an advantage both for the conservation of the endangered species and for the local community and its touristic offer.