By Sam Elliott-Gibbs An adored crane that had a very close bond with zookeeper and ignored all other birds has died at the age of 42. Walnut, who became an internet celebrity after she selected one of the establishment’s workers as her mate, passed away leaving animal lovers upset. She is survived by eight chicks, the loving staff at the Smithsonian’s National Zoo and Conservation Biology Institute, and by Chris Crowe, a human zookeeper whom Walnut regarded as her mate for nearly 20 years. “Walnut was a unique individual with a vivacious personality,” Crowe said, in a statement released by the…