Date of this Version
PROCEEDINGS OF THE NORTH AMERICN CRANE WORKSHOP 13:85-89
We investigated a possible size difference in whooping cranes (Grus americana) captive-reared for 2 reintroduction methods to establish a migratory population in eastern North America. Cranes reared for ultralight aircraft-led migration (UL) to Florida were significantly larger than cranes reared for direct autumn release (DAR) on the natal area in central Wisconsin. Mean tarsal length was 315.5 ± 0.98 (1 SE) and 308.1 ± 1.87 mm, respectively, for UL and DAR males and 296.9 ± 1.03 and 290.8 ± 2.60 mm, respectively, for UL and DAR females. Because of the different rearing schedules, eggs for the DAR method were generally laid later than eggs for UL. Eggs later in the laying sequence had lower weights and resulted in smaller birds, although this overall effect was small. Size difference did not appear related to genetic factors. Although survival to 5 years after release was not significantly related to size within groups of the same sex and release method, captive-rearing effects such as size on survival and behavior of released birds should be considered in assessment of reintroduction programs.