Washington (CNN) -- There is a new grounds crew at the Historic Congressional Cemetery in Washington but these landscapers don't bring lawn mowers, just their appetites.
About 30 goats were released into an overgrown area adjacent to the cemetery on Wednesday and another trailer full were waiting to join them later.
The assignment for these four-legged landscapers: eat the invasive plant species weighing down trees. If no action is taken the trees could eventually fall and destroy historic gravesites.
A little camera shy, the goats were hesitant to emerge before a crowd of children and reporters. Owner, Brian Knox reassured his goats, coaxing some of them out individually by name.
"You get a name if you've got a lot of charisma or if you are a real pain in the butt," Knox joked later.
But soon after a glimpse of the all-you-can-eat buffet which awaited them, the goats were out and busy chowing down.
These goats will continue grazing in an enclosed area next to the cemetery for the six or seven days.
During that time, they will eat almost anything they encounter, including flowers, vines, brush, and bark. Special enzymes in their stomach allow goats to eat plants that are poisonous to humans and other animals.
"Poison Ivy is probably their favorite," explained Knox.
The Historic Congressional Cemetery is still in use today. It is the final resting place for many 19th century military heroes, congressmen, and political figures including two vice presidents and a Supreme Court justice.
Since the grounds are located within the Anacostia Watershed, the goats are an environmentally friendly alternative to using pesticides, herbicides or machinery that could produce pollution.
Light on their feet, the goats are also much gentler on the ground than heavy machinery.
And it's cost effective, too.
Paul Williams, president of the Historic Congressional Cemetery, said that employing 70 goats for a week will cost the cemetery about $4,000.
"That comes down to about 25 cents an hour per goat."
This money saving technique is apparently not new in Washington.
During World War I, sheep could be found grazing on the South Lawn of the White House to save money and manpower. Their wool was auctioned to raise money for the Red Cross.
Members of the cemetery grounds crew don't have to worry about losing their jobs just yet. Williams said that they will continue to use lawn mowers to maintain the actual historic burial sites.