L.A. Zoo elephant enclosure appears empty amid relocation controversy

The elephant enclosure at the Los Angeles Zoo appeared to be empty Tuesday, prompting concerns from activists wondering whether Billy and Tina, the aging inhabitants, were transferred to another zoo.

The L.A. Zoo announced its decision to move elephants Billy, 40, and Tina, 59, to the Tulsa Zoo last month, frustrating animal rights advocates who have argued they should be retired in a…