Individual study: Post-release survival of hand-reared and parent-reared Mississippi sandhill cranes Grus canadensis pulla released at Mississippi Sandhill Crane National Wildlife Refuge, Mississippi, USA
Ellis D.H., Gee G.F., Hereford S.G., Olsen G.H., Chisolm T.D., Nicolich J.M., Sullivan K.A., Thomas N.J., Nagendran M. & Hatfield J.S. (2000) Post-release survival of hand-reared and parent-reared Mississippi sandhill cranes. The Condor, 102
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Artificially incubate and hand-rear cranes in captivity
A replicated, controlled study in a breeding centre in Mississippi, USA, between 1989 and 1996 (Ellis et al. 2000) found that first-year survival of captive-bred, hand-reared Mississippi sandhill cranes Grus canadensis pulla was higher than for captive-bred, parent-reared birds (approximately 85% survival for 56 hand-reared birds vs. 77% for 76 parent-reared birds). Hand-reared birds were reared with mounts of brooding adults and heat lamps, and were taught to feed by costumed humans with mounts of crane (see ‘Use puppets to increase the survival or growth of hand-reared chicks’ for more information). Details of the releases are discussed in ‘Release captive-bred individuals’.
Release captive-bred individuals into the wild to restore or augment wild populations of cranes
A replicated, controlled study in a breeding centre in Mississippi, USA, between 1989 and 1996 (Ellis et al. 2000) found that first year survival of captive-bred Mississippi sandhill cranes Grus canadensis pulla was high, with approximately 80% of 132 birds surviving. Birds were released either in mixed flocks (both hand-reared and parent-reared birds) or non-mixed flocks (with just one rearing type). Survival rates over four years were highest for hand-reared birds in mixed flocks (approximately 95% survival for 17 birds), followed by parent-reared birds in mixed flocks (89% of 31 birds), hand-reared in non-mixed flocks (78% of 39 birds) and were lowest in parent-reared, non-mixed flocks (56% of 45). By the end of the study, however, differences between parent and hand-reared birds were no longer statistically significant, although mixed flock birds still had higher survival. Birds were kept in ‘cohorts’ for four to five weeks, before being moved to the release site and kept for a month in uncovered pens before wing brails (which prevent flying) were removed in December. Details of hand-rearing are found in ‘Artificially incubate and hand-rear birds in captivity’.