The effects of rearing method on social behaviors of mentored, captive-reared juvenile California condors

Abstract

Puppet-reared and parent-reared captive-bred California condor (Gymnogyps californianus) juveniles were studied before their release into the wild. Behavioral data were collected during social interactions within two cohorts of juveniles (N= 11) and their adult mentors (N=5). The purposes of this study were to (1) document the social behaviors of mentored juvenile California condors, and (2) compare social behaviors for two different rearing methods (puppet-reared versus parent-reared) during two phases of the mentoring process (San Diego Wild Animal Park versus release sites). Of the 17 behaviors examined by 2 × 2 analyses of variance (ANOVAs), two significant interactions between the rearing method and mentoring phase were found: pulls feathers and feeds alone. For both behaviors, parent-reared condors engaged in these activities more often at the zoo and less often at the release pens than did the puppet-reared condors. The main effect of rearing was also significant for two behaviors: near others, and receives contact aggression from other. Parent-reared birds were more likely to be near another bird and receive contact aggression, regardless of mentoring phase, than puppet-reared birds. The effect size for 16 of the 17 behaviors was greater for the rearing method than for mentoring phase. Rearing method differences may persist long-term, as parent-reared adult mentors were significantly more aggressive than puppet-reared adult mentors. Dominance relations were examined for both cohorts, with the first cohort exhibiting a strong linear relationship ( h′ - 0.86, P = 0.018), whereas the second cohort exhibited a moderate but non-significant linear hierarchy ( h′ = 0.63, P = 0.21). The rearing method had no effect on dominance among the juveniles, but adults were probably dominant to juveniles (P = 0.052; the difference was nearly significant). Although social behaviors between the two rearing groups were similar in most respects, this study is the first to document measurable differences between puppet- and parent-reared captivebred California condor juveniles. © 2007 Wiley-Liss, Inc.