Rather than using a lawn mower or other landscaping equipment on overgrown fields, O'Hare is following in the footsteps of other airports by using farm animals to eat up the vegetation. According to the Chicago Sun-Times:
"O’Hare International Airport just hired some hungry employees: 14 goats, five sheep, three burros and two llamas.
And the airport’s youngest employee? A male lamb born Tuesday morning on an O’Hare field."