A 21-year-old emu named Adam was killed at a Missouri zoo after sustaining head trauma from softball-sized hail that battered the city of Springfield during a historic storm. Adam, a female emu at the Dickerson Park Zoo, suffered fatal injuries during the severe weather Tuesday. Zoo officials say that can be blamed on the emu's instinct to lie down to take cover, according to The Associated Press . Oscar, a 17-year-old rhea bird, was injured in the storm, but is on the mend and receiving pain medication. Rhea birds are distant cousins of emus. All of the zoo’s other animals are safe and the facility reopened Thursday after workers cleaned up “significant damage” from the hail. “Please note: some small birds will be off exhibit until skylights are repaired,” the zoo said in a post on Facebook . “There is still much to be done, but please come visit.” The female emu named Adam is seen at the at the Dickerson Park Zoo in Springfield, Missouri, in this undated image.…