Apparently monkeys don't have huge warning signs letting others know that they're pregnant. No weird cravings. No complaining about their aching back. Nothing.

That's why the staff at John Ball Park Zoo was kind of stunned to see a baby monkey on the premises this week.

Yaki and Helen are two white faced saki monkeys, native to the jungles of South America, and even though they're getting up there in years, they still like to get it on, which is the reason Helen gave birth to a baby this week.

The saki monkey couple are near the high end of the breeding age for their species, so the baby was a surprise to staff at the zoo.

“So far, everything we’ve seen has been really positive,” Bill Flanagan, the area curator for primates at the zoo, told WOOD TV8. “Baby’s been clinging to mom really well. Bright and alert. We’ve seen it nursing. We give them access to the exhibit. She’s been coming out and showing off the baby then going back into the exhibit.”

Staff say they won't know the gender of the newborn until it gets big enough for a veterinary exam.

It's the fourth offspring of Yaki and Helen. The others have grown and live at other zoos. The monkey is barely visible to zoo guests, as it is still clinging to its mother and will for a while.

For more about saki monkeys at the zoo, click here.