Action: Use puppets to increase the survival or growth of hand-reared chicks
Three replicated studies from the USA and Saudi Arabia found that corvids and bustards raised using puppets did not have higher survival, dispersal or growth than conventionally hand-reared chicks.
A potential problem with hand-rearing chicks is that they will ‘imprint’ on the humans raising them and be unable to adjust to life in the wild or breed with conspecifics. It has therefore been suggested that chicks should be fed with as little human contact as possible and that puppets, designed to look like parent birds, be used to feed them.
Supporting evidence from individual studies
A replicated ex situ study in Idaho, USA (Whitmore & Marzluff 1998), found that the growth of raven Corvus corax chicks did not vary between 30 individuals fed with a puppet and 82 fed by keepers. Post-release survival and reproduction were not compared. This study is also discussed in ‘Artificially incubate and hand-rear birds in captivity’.
A randomised, replicated and controlled study in Idaho, USA, between 1993 and 1995 (Valutis & Marzluff 1999), found that 25 raven Corvus corax chicks (used as surrogates for Hawaiian crows C. hawaiiensis and Mariana crows C. kubaryi) hand-raised using puppets did not behave differently towards other ravens before or after release, or differ in dispersal from the release site, compared to 49 chicks raised without puppets. Puppet-rearing appeared to increase post-release survival, but the whereabouts of 49% of released birds were unknown, adding considerable uncertainty to this conclusion. Puppet-raised birds were more fearful of keepers following release, which could be beneficial for some species. Puppet-reared birds were separated from each other at 7-10 days old (before their eyes opened).
A replicated trial in Saudi Arabia in 1995 (van Heezik et al. 1999) found that hand-reared houbara bustards Chlamydotis undulata macqueenii raised with a puppet to minimise human contact were not significantly more likely to survive following release at a desert site, than control (reared with human contact) birds (42% of 12 puppet-reared birds alive the year after release vs. 27% of 12 controls). This study also is also discussed in ‘Use ‘anti-predator training’ to improve survival after release’.
- Whitmore K.D. & Marzluff J.M. (1998) Hand-Rearing Corvids for Reintroduction: Importance of Feeding Regime, Nestling Growth, and Dominance. The Journal of Wildlife Management, 62, 1460-1479
- Valutis L.L. & Marzluff J.M. (1999) The Appropriateness of Puppet-Rearing Birds for Reintroduction. Conservation Biology, 13, 584-591
- van Heezik Y., Seddon P.J. & Maloney R.F. (1999) Helping reintroduced houbara bustards avoid predation: effective anti-predator training and the predictive value of pre-release behaviour. Animal Conservation, 2, 155-163