In this study, nests belonging to the European Red Wood ant Formica pratensis Retzius, 1783 in the Yildiz (Stranjha) Mountains of Kırklareli province of Türkiye were examined in the spring and autumn periods. Field studies were carried out in previously registered regions and in Çağlayık Village, which was registered for the first time. The field results determined that 31 of the 43 known nests were destroyed, and the current number of nests was 31 with 19 newly detected nests. During the field studies of the nests in two separate periods, diameter and height data, nest shape, and habitat characteristics were examined and recorded on the nest identification cards. The results demonstrated that all of the nests are monodome type built in the forest clearing and mostly in sun-drenched areas. Nest volumes were evaluated as an indicator for determining colony density, and the measurements in the two periods were compared to determine the effect of seasonal changes. The factors causing the destruction of nests were determined as a factor causing nest destruction, habitat destruction, and conversion of the land into different usage areas. Distribution maps were prepared with the coordinate data of the nests. Living areas (area of occupancy, AOO) were calculated with a 2x2 km grid added to the distribution maps, and extent of occurrence (EOO) was calculated with appropriate polygons. The results demonstrated that with the destruction of 31 nests, AOO decreased by 45% and EOO by 40% over a period of 4 years. Adding newly found nests to the remaining nests with the current distribution map prepared showed that AOO occupies a smaller area by 20% and EOO by 26% compared to the previous distribution in 2014. Regarding nest volumes, there was no significant difference in the two periods. The data obtained indicates the high extinction rate in a short time and the fact that the current distribution is lower than the previous distribution despite the new nests, indicating the importance of conducting a conservation study.