This project is great in its intentions and on paper. I applaud the French zoo for its involment and goodwill. I hope my futher text is not seen as criticue of parc animlier de sainte croix.
However in reality, mortality of capercillie chicks released from both current Czech breeding facilities in Beskydy mountains and Šumava is 100% - since beginning till today. I had seen some internal report papers and unfortunately, most their chicks perish within 2 weeks and basicaly non survive first year. Zero proven breeding of released birds within last 50 years of captive-bred bird releases.
The only good capercillie population left in Czechia is in Šumava mountains. And it currently grows due reasons that are not fully understood by wildlife officials / researchers. What probably helps is large-scale protection measures done in national park and exclusive military area Boletice nearby. It includes closure of large patches of land for public, closed hicking paths (which provoked a lot of protests by both local people and tourists). There is also change in agro-forestry practices. Large-scale die-offs of fir trees due to bark beetle. Natural return of wolves into the area and recovery of lynx, both species suppress mesocarnivores like red fox (and that helps capercillie chick survival odds). But again, nobody really knows what of these changes actually has the most impact.
Capercilie population in Beskydy is miniature and continues to diminish and will soon die out. Despite releases of captive bred chicks.