A white tiger cub growls at the Buenos Aires Zoo in Argentina, Thursday, March 21, 2013. The cub's mother, Cleo, a captive Bengal white tiger, gave birth to two females and two males on Jan. 14. (AP Photo/Natacha Pisarenko)
Four white tiger cubs play in their enclosure at the Buenos Aires Zoo in Argentina, Thursday, March 21, 2013. The cubs' mother, Cleo, a Bengal white tiger, gave birth to two females and two males on Jan. 14. (AP Photo/Natacha Pisarenko)
A zoo worker places a white tiger cub with his three siblings at the Buenos Aires Zoo in Argentina, Thursday, March 21, 2013. Cleo, a female Bengal white tiger, gave birth to two females and two males on Jan. 14. (AP Photo/Natacha Pisarenko)
Cleo, a female Bengal white tiger, stands with two of her four cubs at the Buenos Aires Zoo, Argentina, Thursday, March 21, 2013. Cleo gave birth to two females and two males on Jan. 14. (AP Photo/Natacha Pisarenko)
A white tiger cub peers from behind wood stumps inside its enclosure at the Buenos Aires Zoo in Argentina, Thursday, March 21, 2013. Cleo, a female Bengal white tiger, gave birth to two females and two males on Jan. 14. (AP Photo/Natacha Pisarenko)
Cleo, a female Bengal white tiger, stands with two of her four cubs at the Buenos Aires Zoo, Argentina, Thursday, March 21, 2013. Cleo gave birth to two females and two males on Jan. 14. (AP Photo/Natacha Pisarenko)
Cleo, a female Bengal white tiger, looks through a window from within her enclosure at the Buenos Aires Zoo in Argentina, Thursday, March 21, 2013. Cleo gave birth to two female and two male cubs on Jan. 14 at the zoo. (AP Photo/Natacha Pisarenko)
Four white tiger cubs lay in their enclosure at the Buenos Aires Zoo in Argentina, Thursday, March 21, 2013. The cubs' mother, Cleo, a captive Bengal white tiger, gave birth to two females and two males on Jan. 14. (AP Photo/Natacha Pisarenko)