Park Record Media Center

The Smithsonian National Zoo's female Sumatran tiger cub Sukacita takes a swim reliability test at the zoo's moat in Washington, Wednesday, Nov. 6, 2013. The two 13-week-old Sumatran male and female cubs named Bandar and Sukacita, were able to keep their heads above water, navigate to the shallow end of the moat and climb onto dry land, passing this critical step. The cubs are ready to explore the yard with their mother, 4-year-old Damai. (AP Photo/Manuel Balce Ceneta) ( National Zoo Tiger Cubs )

A female Sumatran Tiger cub named Sukacita is lifted by biologist Leigh Pitsko (R) after the cub performed her "swim test" in a moat of the Great Cats exhibit at the National Zoo November 6, 2013 in Washington, DC. (Photo by Win McNamee/Getty Images) ( 77222142 )

A female Sumatran Tiger cub named Sukacita is lifted by biologist Leigh Pitsko (R) after the cub performed her "swim test" in a moat of the Great Cats exhibit at the National Zoo November 6, 2013 in Washington, DC. (Photo by Win McNamee/Getty Images) ( 77222144 )

A female Sumatran Tiger cub named Sukacita is dried off by biologist Leigh Pitsko after performing the cub performed her "swim test" in a moat of the Great Cats exhibit at the National Zoo November 6, 2013 in Washington, DC. (Photo by Win McNamee/Getty Images) ( 77222129 )

A male Sumatran Tiger cub named Bandar performs his "swim test" in a moat of the Great Cats exhibit at the National Zoo November 6, 2013 in Washington, DC. (Photo by Win McNamee/Getty Images) ( 77222105 )

A female Sumatran Tiger cub named Sukacita is dried off by biologist Leigh Pitsko after performing the cub performed her "swim test" in a moat of the Great Cats exhibit at the National Zoo November 6, 2013 in Washington, DC. (Photo by Win McNamee/Getty Images) ( 77222127 )

A male Sumatran Tiger cub named Bandar is carried by curator Craig Saffoe after the cub performed his "swim test" in a moat of the Great Cats exhibit at the National Zoo November 6, 2013 in Washington, DC. (Photo by Win McNamee/Getty Images) ( 187112783 )

A male Sumatran Tiger cub named Bandar is carried by curator Craig Saffoe after the cub performed his "swim test" in a moat of the Great Cats exhibit at the National Zoo November 6, 2013 in Washington, DC. (Photo by Win McNamee/Getty Images) ( 77222161 )

A male Sumatran Tiger cub named Bandar performs his "swim test" in a moat of the Great Cats exhibit at the National Zoo November 6, 2013 in Washington, DC. (Photo by Win McNamee/Getty Images) ( 77222102 )

A female Sumatran Tiger cub named Sukacita is held by biologist Leigh Pitsko after the cub performed her "swim test" in a moat of the Great Cats exhibit at the National Zoo November 6, 2013 in Washington, DC. (Photo by Win McNamee/Getty Images) ( 77222152 )

A female Sumatran Tiger cub named Sukacita is placed into a moat by biologist Leigh Pitsko (R) before the cub performed her "swim test" at the Great Cats exhibit of the National Zoo November 6, 2013 in Washington, DC. (Photo by Win McNamee/Getty Images) ( 77222149 )

A three-month-old Sumatran tiger cub named "Bandar" is carried toward the tiger exhibit moat by Craig Safoe, right and Leigh Pitsko for a swim reliability test at the National Zoo in Washington, Wednesday, Nov. 6, 2013. (AP Photo/Manuel Balce Ceneta) ( National Zoo Tiger Cubs )

A three-month-old Sumatran tiger cub named "Sukacita" is lowered into the tiger exhibit moat for a swim reliability test at the National Zoo in Washington, Wednesday, Nov. 6, 2013. (AP Photo/Manuel Balce Ceneta) ( National Zoo Tiger Cubs )

A three-month-old Sumatran tiger cub named "Sukacita" paddles across the tiger exhibit moat during her swim reliability test at the National Zoo in Washington, Wednesday, Nov. 6, 2013. (AP Photo/Manuel Balce Ceneta) ( National Zoo Tiger Cubs )

A three-month-old Sumatran tiger cub named "Sukacita" is toweled off after passing her swim reliability test in the moat at the tiger exhibit at the National Zoo in Washington, Wednesday, Nov. 6, 2013. (AP Photo/Manuel Balce Ceneta) ( National Zoo Tiger Cubs )