The Appropriateness of Puppet-Rearing Birds for Reintroduction

Abstract: Captive propagation and reintroduction programs for rare and endangered species rarely include testing of techniques prior to initiation of recovery efforts. To experimentally test the effects of rearing social, altricial birds with or without a conspecific, parental model (a puppet), we used Common Ravens ( Corvus corax ) in southwestern Idaho as surrogates for the endangered Hawaiian Crow ( Corvus hawaiiensis ) and Mariana Crow ( Corvus kubaryi ). A puppet is believed to reduce sexual and filial imprinting on human caretakers. We raised 49 ravens without a puppet and 25 ravens with a puppet. We initiated puppet-rearing when birds were 7 days of age and continued until 60 days of age, when nestlings could eat well on their own. The influence of puppet-rearing was tested as part of a factorial design that also tested for the effects of conspecific tutoring and age at release. Rearing ravens with a puppet did not affect social behaviors prior to release, dispersal from the release area, or integration with wild birds after release. Ravens raised with a puppet, however, were more fearful of caretakers and more vigilant prior to release, characteristics that may have improved their chances for survival after release. It is important for researchers to consider the species and the desired pre- and post-release behaviors to determine if rearing with a puppet is appropriate for their recovery efforts. These considerations can be taken into account by using a surrogate species prior to recovery efforts and creative management approaches in the initial phases of an endangered species recovery program.