Long‐term apparent survival of capercaillie (Tetrao urogallus) translocated from Sweden to east Germany

The capercaillie Tetrao urogallus formerly inhabited the forests of Lower Lusatia in eastern Germany but became regionally extirpated by the late 20th century following extensive habitat loss and fragmentation. In response, a reintroduction program was initiated in 2012 after approximately one decade of habitat restoration. Between 2012 and 2024, adult capercaillies were captured in Sweden, and a subset of eggs laid by transported females was reared under the mother‐assisted ‘born to be free' method, providing two groups that differed in age and early‐life history. We evaluated long‐term demographic performance of translocated capercaillie using non‐invasive genetic capture–mark–recapture, complemented by GPS telemetry. Individual encounter histories were used to estimate apparent annual survival of males and females over a 13 years period, compare survival between wild‐caught individuals and birds reared under the mother‐assisted ‘born to be free' method, and assess possible effects of monitoring intensity. Apparent annual survival of genetically monitored translocated males (0.77) was within the range reported for extant populations. In contrast, genetically estimated survival of females was substantially lower (0.44), whereas radio‐tracked females showed higher survival (0.60), suggesting that reduced female apparent survival largely reflects lower site fidelity rather than mortality alone and highlighting limitations of non‐invasive monitoring for females. Survival of ‘born to be free' juveniles was lower than that of wild‐caught adults in both females (0.18 versus 0.45) and males (0.41 versus 0.71). However, age‐related differences in apparent annual survival were not evident when body mass was used to distinguish potential wild‐caught yearling females from adult hens. Overall, sex‐specific site fidelity and reduced survival of juveniles emerge as key demographic constraints to population establishment, whereas survival of adults, particularly males, comparable to reference populations suggests that adult survival per se is unlikely to limit translocation success.