With a few whistles and command calls, Brian Cash and his crew of border collies corral a herd of sheep headed for breakfast, lunch and dinner at Atlanta's Hartsfield-Jackson airport.
"There are very few things that they turn away. They love poison ivy. They eat blackberries that have thorns. And they eat these things willingly. If they have options they will still select those types of foods," said Cash, the owner of Ewe-niversally Green.
In just two days, his herd of 100 has eaten through nearly half of the waist high weeds in the test acre lot along Riverdale Drive near the airport.
The airport has about 3,000 acres of raw land it must maintain, to make sure weeds and seedlings don't grow into habitat for birds and other wildlife that could endanger activities at the airport.
"So far I'm liking what I see," said Chris Davis the assistant maintenance director for Hartsfield Jackson International Airport.
A private donor paid for the airport to test out the sheep for a week, to see if they would eat what's on the menu and how fast the cheerful chompers could do it.
The airport can then do the math, to compare costs with chemicals, machines and manual labor.
"The cost factor to this is probably the biggest unknown that I have," said Davis.
Other airports have given the furry weed whackers a try.
Chicago is taking bids right now to hire a crew.
San Francisco uses them every year to control the brush in a protected wetlands area, where pesticides aren't allowed.
Seattle tried it one year for similar reasons, but says it had to build too many cages to protect the plants it wanted to keep.
Beyond cost is safety.
"That particular hillside leads up to a runway and so I have to be able to control and make sure I don't get any of the animals that may want to migrate up the hill," said Davis.
Right now, a solar operated electric fence keeps the goats in check, but the TSA may want something more substantial and Cash would need a way to access his flock several times a day.
The airport says it will take several months to crunch the numbers and make its decision.