Accelerating ocean exploration.

COVER Young whooping cranes (Grus americana) follow an ultralight aircraft. Each year, endangered whooping cranes are reared in captivity and artifi cially trained by ultralight aircraft on their fi rst lifetime migration from Wisconsin to Florida. Analyses of data from subsequent unaided migration events show that migratory performance improves over many years and that social learning from older birds plays an important role. See page 999.