Based on this year’s marking and recapture data, the reintroduced population of the Chapman's Blue (Polyommatus thersites) at Dívčí hrady is estimated at approximately 2,100 individuals, with about 1,534 males and 579 females, showing a markedly skewed sex ratio compared to last year’s balanced 1:1 proportion. In total, 629 butterflies were marked this season (484 males and 145 females), slightly fewer than the 650 individuals recorded in 2024. Several males reached a maximum recorded lifespan of 35 days, exceeding the previous record of 27 days (2020), while the longest confirmed survival among females was 16 days, though based on fewer recaptures. The observed male bias may be due in part to favourable weather during the survey, as most captures occurred under warm, sunny conditions when the more conspicuous blue males are easier to detect. The reintroduced population has now persisted successfully at Dívčí hrady for eight years, despite several declines during climatically unfavourable seasons.
Supported by the project: Municipal biological diversity: application of modern practices to support biodiversity in cities and their surroundings.
