MILWAUKEE -- A brand-new baby giraffe arrived on Halloween at the Milwaukee County Zoo -- much to the surprise of zookeepers.

His unexpected arrival left zookeepers speechless.

"When I first seen him, I thought, 'What are you doing here? Who are you?' And it was a big surprise," zookeeper Rich Schweitzer said. "The baby is small, and the mother didn't really show it that much."

The baby giraffe is named Mark, after Schweitzer's son.

Malindi, Mark's mother, weighs almost 3,000 pounds. So what's 112 more?

Because this species of giraffe is common, Malindi is kept on birth control that apparently didn't work.

"She's pretty good at keeping secrets, I guess," zoo visitor Terry Ullman said.

The gestation period for giraffes is 15 months. Mark's father died last year, so Schweitzer never thought to check Malindi for pregnancy.

He's worked at the zoo for eight years, and his colleagues are respecting his seniority by cutting him some slack.

"No, they've been very kind. What goes around goes around," Schweitzer said.

The new arrival will be at the zoo for about two years. Then he'll be moved to another zoo so the population doesn't grow again.