The Milwaukee County Zoo has a new and surprising addition — well, two additions — to its Small Mammals Building. Unknown to zookeepers, two sugar gliders were born last fall. They were put on display late last month. The small, tree-dwelling creatures join two baby monkeys as the latest additions to 10001 W. Blue Mound Rd.

The sugar gliders were born completely unknownst to the zookeepers.

"We didn't even know (the mother) had had the babies until one zookeeper put her hand in the box and found them," said Cassondra Manteau, a zookeeper in the Small Mammals Building, where the sugar gliders, also known as flying squirrels, are housed.

According to Manteau, sugar gliders are marsupials and born into pouches, making it hard for zookeepers to see them.

"It was a pretty big surprise," she said.

The two baby sugar gliders are among four of the newest additions to the Milwaukee County Zoo this spring. Viewers can also see a newborn Goeldi monkey and a young spider monkey.

"It's really kind of unusual for people to get to see baby animals like this," said Jennifer Diliberti, the zoo's public relations coordinator. She said there is typically an increase in business at the zoo after the birth of animals because baby animals are "cute and cuddly."

Among the "cute and cuddly" creatures are Ella and Rose, the two sugar gliders born in November. Sugar gliders are actually gliding possums often found in Australia, New Guinea and Tasmania, according to a recent Milwaukee County Zoo press release. They are silver and have dark stripes running down their backs. While Ella and Rose weighed 19 grams at birth, they will grow to become the size of the average hamster. They will be fed a diet of fruit, vegetables and insects, according to the press release.

According to Manteau these animals are "very, very, very timid" and can best be seen at feeding time, which is held daily at 2:30 p.m.

Also new to the Small Mammals Building is a three-month-old Goeldi monkey. It has yet to be named, but Diliberti said that she expects zookeepers will name the animal in the upcoming weeks. According to Manteau the baby is easier to see than the sugar gliders because it can often be found riding on the other monkey's backs.

"If you know it's there and you know what to look for, you can see it right away," Manteau said.

Goeldi monkeys are typically found in the upper Amazonian rainforests in South America, Diliberti said, and they are known for their ability to jump up to four feet horizontally.

Viewers can also look for Colo, the baby spider monkey in the zoo's Primates of the World Building. Colo was born nine months ago and can usually be spotted hanging on her mother's back.