Reintroduction of Parent-Reared and Semi-Wild Chicks of Red-Crowned Grus japonensis and White-Naped Cranes Antigone vipio in Russia: Lessons from 29 Years of Experience

Abstract

Abstract Red-crowned Grus japonensis (IUCN status: Endangered) and White-naped Antigone vipio (IUCN status: Vulnerable) cranes are both rare, with wild populations of ∼3,000 and ∼6,000 individuals, respectively. Since 1991, the Rare Bird Reintroduction Station at the Khingansky State Nature Reserve, Russia, has been rearing and reintroducing chicks of both species to bolster wild populations. The station uses two different chick-rearing methods: (1) the “parent-reared” method, in which chicks are raised in enclosures by natural parents and stay with them until their release into the wild, and (2) the “semi-wild” method, a modification of hand-rearing, in which cohorts of 2–7 chicks spend most of their time together in an enclosure but are guided on daily excursions outside the enclosure, under supervision of a keeper from a distance of 30–50 m. We have assessed and compared apparent survival of crane chicks reared under these methods. Of the 165 juveniles released into the wild from 1991–2019 (104 Red-crowned; 61 White-naped), no difference was found between apparent survival of parent-reared and semi-wild chicks. Six-month apparent survival of Red-crowned Cranes was 84.2% (95% confidence interval: 75.3–90.3%); for White-naped Cranes –89.5% (95% CI: 83.9–93.3%). Both parent-reared and semi-wild chicks were later observed in mated pairs with their own offspring (17 chicks in total), coupling with either other reintroduced birds or with wild individuals. We conclude that both the parent-reared and semi-wild methods had similar outcomes with respect to apparent survival. However, since the semi-wild method is less costly with respect to time (i.e., more juveniles can be released annually using this method) we recommend that it be used whenever possible to bolster these Endangered and Vulnerable populations.