An Arizona zoo is keeping a close eye on a litter of lion cubs born just before Christmas.
Reid Park Zoo in Tucson announced that Kaya give birth to one cub on Dec. 23. The next day, the zoo confirmed five cubs were born but one did not survive.
"A litter of five cubs is unusual," said zoo veterinarian Alexis Moreno.
Moreno said the zoo is closely monitoring the health of the remaining cubs.
The mortality rate for cubs up to 1-year-old is close to 30 percent in zoos and significantly higher in the wild.
All four cubs are gaining weight but veterinary staff remains concerned about one male who appears weaker than the others.
"I am cautiously optimistic at this point," Moreno said.
Kaya and her cubs have access to two bedrooms and a cub den. The mother is eating well, nursing, and is protective of her young, the zoo said in a statement.
The father, Shombay, is separated from the rest of the pride for safety.
This is Kaya and Shombay's second litter of cubs at Reid Park Zoo. She delivered three cubs in July 2011 and all three offspring are now grown and at other accredited zoos.
Reid Park Zoo partners with colleague facilities to make responsible breeding decisions for the protection of the species.
The zoo said the cubs will remain behind the scenes for between six to eight weeks before the public can get a glimpse of them.
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