The Smithsonian's National Zoo welcomed this year's second litter of African lion (Panthera leo) cubs. On Aug. 31, Shera gave birth to four cubs—the first litter for 5-year-old Shera and the first surviving litter for 4-year-old male Luke. The cubs were born between 10:30 p.m. Monday and 2:30 a.m. Tuesday and since then have been mobile and appear to have nursed. This footage from the web cam in the den gives a sneak peek at the new cubs. "Our hope is that her maternal instincts will kick in quickly, but we are keeping in mind that this whole experience is new to her," said Kristen Clark, a lion and tiger keeper. "We will be closely monitoring how she reacts to her cubs, since there is a possibility that she could reject them. Nababiep [Shera's 6-year-old sister] was an excellent mother to her first cub, and we have every indication that Shera will be the same." Keepers suspect that Nababiep is pregnant again and will monitor her behavior in the coming weeks.