Two tiger cubs born at Toledo Zoo

This den cam image shows two newborn tiger cubs, highlighted in the light gray circles, who were born at the Toledo Zoo to mother Marta. TOLEDO ZOO Enlarge

The Toledo Zoo announced Friday the birth of two Amur tiger cubs.

The newborn big cats were born Monday to first-time mother, Marta.

"We remain cautious because litters to first-time mothers often do not survive,” the zoo posted online. “If all goes well, they should be on exhibit some time in January, 2012."

The cubs’ genders have not yet been determined. Amur tigers are classified as critically endangered, with an estimated population of fewer than 400 in the wild.

"Marta appears to be doing a really good job caring for the cubs, but we remain cautious because litters to first-time mothers often do not survive due to poor mothering skills," said Dr. Randi Meyerson, curator of mammals. "So far, Marta is displaying very good maternal behavior."

The average litter size for Amur tigers is two to four cubs.

Other newborns at the zoo include a baby giraffe named Tuli born on July 23 and a male African elephant calf, Lucas, who was born June 3. The baby pachyderm weighed just over 300 pounds when he was born

When Tuli was born, she stood 6 feet tall and weighed about 160 pounds at birth. She became the fifth member of the Zoo’s giraffe herd. Tuli joined her older brother, Enzi, along with father Mowgli and an unrelated female, Charlotte, on exhibit.

All five giraffe are Masai giraffe, the tallest animals on the planet, standing an average of 16 to 18 feet when fully grown. Despite their size, giraffe can run at speeds up to 35 mph. They can be identified by their irregularly shaped spots, which are as unique and identifiable as human fingerprints.

Online: toledozoo.org