A herd of goats, burros, sheep and llamas are chewing their way through the grounds of O’Hare International Airport in Chicago. The Chicago Department of Aviation showed off their latest “employees” this week, though the animals have been at work, clearing the vegetation around the airport for almost a month.

The group of 14 goats, five sheep, three burros and two llamas will graze inside fenced areas around the airport at least until the end of 2014. Officials say the animals were brought to the airport as a sustainable way to clean up the dense scrub vegetation that covers much of the grounds.

“It gets pretty rocky under here,” said Rosemarie Andolino, CDA commissioner. pointing to a five-acre field of grass and brush behind her. “And there (are) areas where it kinda goes up and down and lawnmowers in many cases don’t provide or aren’t adequate to get to some of these areas.”

Andolino said the contract for the goats won’t exceed $19,500, and it expires by the end of 2014. The commissioner didn’t have estimates as to how much it cost to maintain the grounds before the animals, yet a spokeswoman maintained there may be some cost savings down the road.

The herd won’t be eating at the same spot everyday — Andolino says they’ll move around to different places on the airport’s grounds, depending on need. As for concerns about the animals during brutal Chicago winters, officials say the herd will only be out as long as weather permits.

Most of the animals in the O’Hare herd come from Settler’s Pond — a shelter for abandoned animals in Beecher, Ill. — but four of them were originally owned by Joseph Arnold, head of Central Commissary Holdings, LLC. The airport contract isn’t technically their first job: Arnold’s four goats used to provide milk for the goat cheese served at Chicago restaurant Butcher and the Burger.

Though they might seem an unlikely sight among the security fences and planes flying overhead, the burros, goats, sheep and llamas Tuesday seemed to make themselves quite at home. One of the sheep even gave birth to a lamb Tuesday, and all the animals gathered around to greet him.

“It’s a little boy and his name is O’Hare,” said Pinky Jenota, one of the caretakers from Settler’s Pond. “He’s doing great, he was up suckling on mom, planes flying overhead. He didn’t flinch, Mom didn’t move - everybody’s content.”

For now, the herd will continue munching around a five acre space on the airport grounds. Officials say they should finish that section in the next few weeks, and then it’s on to the next spot.

Lauren Chooljian is WBEZ’s Morning Producer/Reporter Follow her @laurenchooljian .