Whooping crane Grus americana chick mortality and management intervention

Translocation of captive-reared animals is widely used as a tool for endangered species recovery. Frequently, translocated populations have relatively low initial productivity, requiring management intervention. A translocated population of whooping cranes Grus americana in central Wisconsin is such a case. We examined chick mortality for this population and used daily chick survival rates as our response variable to model several parameters including phenology, chick age, energetics and parent age and experience. We also developed and evaluated adoption techniques using sandhill cranes Grus canadensis to mitigate the effects of high chick mortality and increase the probability of fledging. Our results illustrate the challenges that translocated populations can face as they encounter novel breeding conditions. We found that whooping crane daily chick survival was relatively low and most mortality events occurred within the first 20 days. Our results indicated that variables related to age of the parents as well as the pair's previous chick rearing experience were useful for predicting daily chick survival. We found that sandhill crane foster parents readily accepted replacement chicks. We also demonstrated adopted chicks acceptance of foster parents and that the chicks' source (captive-born vs wild-born) did not affect success of the adoption. Chick adoption provides several management options that could be used to bypass the period when chicks experience the greatest mortality. Reducing chick mortality and developing techniques to increase the number of fledged chicks is paramount for whooping crane recovery as well as the recovery of other endangered bird species.