The goats have already cleared out a section next to the road that was too thick to see through. It's now littered with gnawed-on branches.
This week, they moved to an even denser area and have started to make headway, though on a recent visit most were enjoying a well-deserved afternoon nap.
"We're working on goat time," Astifan said.
When it comes to clearing unwanted vegetation, goats can provide an ideal alternative to machines and herbicides, according to Eco-Goat founder Brian Knox. They graze in places that mowers can't reach and humans don't want to go, and they eat a wide range of unwanted vegetation, including poison ivy and kudzu.
As they eat, they crush the seeds of plants so they can't sprout in the next growth cycle, something machines don't do. And goats graze all day long, so a herd of 30 will munch through a quarter of an acre in 24 hours.
Knox, who runs a natural resources consulting firm, said he began leasing goats about five years ago and "it was a wild success." Now he has 135 animals, 70 of whom work on a regular basis. Since it's a mixed herd, several dozen kids are born annually. In fact, 12 mothers are on maternity leave.
"We had a flurry of kids on Fourth of July," Knox said.
In addition to Haverford, he has a herd at Belmont Mansion to help get rid of poison ivy from the public gardens, and has twice leased herds to Millbourne, Delaware County, to clear out an area along train tracks.
Big cities such as Seattle have used goats to control weeds, and even homeowners have employed them to clear out backyards.
"They want to knock it back every few years so they don't lose a view," Knox said.
Of course, you can't leave a void in nature. So after the goats are gone, vegetation will grow back. Haverford plans to follow up with a two-legged crew with machinery to clear out what's left and spray small amounts of herbicides to kill off stumps.
The goal is to have a walkable woodland instead of an overgrown forest.
"We want to take it to the point where we can manage it at the most cost-effective rate," Knox said.
Knox leases his goats for about $400 per day plus the cost to erect an electric fence and a barrier fence to keep away spectators. Renting machinery to do the job would cost $2,500 to $3,000 per day, according to Astifan.
At Haverford, which was recently overrun with golf fans during the U.S. Open, the sight of a couple dozen goats on the upscale college campus drew a different kind of crowd: mothers and children rather than sports fans.
The goats didn't disappoint, perching their front hooves on tree trunks so they could pull down branches and nibble the delicious leaves.
Knox visits the site daily to make sure the fence is intact and the goats have water. And answer lots of questions from curious passersby.
"They do the rest," he said. "They're very good at what they do. They don't need much instruction. They just do it."
Contact Kathy Boccella at firstname.lastname@example.org, 610-313-8232 or follow @kathyboccella on Twitter.