Travis using farm animals to control invasive plants

  • Published
  • By Merrie Schilter-Lowe
  • 60th Air Mobility Wing Public Affairs

TRAVIS AIR FORCE BASE, Calif. – With a b-l-e-e-e-a-t here and baaaaaa there, more than 300 sheep and about a dozen goats arrived at Travis Air Force Base, California, to begin grazing duties in the Castle Terrace Preserve area that serves as a habitat for federally listed endangered species.    

The animals will spend several weeks ridding the 20-acre parcel of land of barbed goatgrass and other non-native plants that cannot be managed by yearly mowing.  

“We are targeting barbed goatgrass and tall non-native grasses, many of which are not palatable to grazing animals once they have flowered because of barbs and awns attached to the seeds,” said Lauren Wilson, regional natural resource manager and biological scientist with the Air Force Civil Engineer Center Installation Support Section at Travis. “Targeted grazing allows us to achieve better control of invasive species by targeting a specific growth period of a plant, reducing the likelihood that it will grow to produce seeds.” 

Tall grasses can reduce the number of small mammals using an area, which in turn, reduces habitat for the endangered California tiger salamander. Targeted grazing by sheep and goats will produce shorter grasses than mowing, said Wilson.  

“The sheep and goats will trample much of the grasses, breaking up the spikey parts and the underlying thatch that can inhibit the growth of preferred native species,” said Wilson.

Barbed goatgrass is a winter annual that thrives during fall rains. It matures between May and August, reaching a height of 8 to 20 inches. Barbed goatgrass is native to Eastern and Mediterranean Europe and Western Asia and is believed to have been introduced on the West Coast in the 1900s along with the import of cattle to El Dorado and Sacramento counties, according to the University of California Division of Agriculture and Natural Resources.

Since 2015, AFCEC has worked under a cooperative agreement with the Solano Resource Conservation District to control barbed goatgrass and other invasive species in the Castle Terrace area.  The SRCD is also providing oversight for the grazing project. 

Travis already manages about 315 acres of land for cattle and horse grazing on the base’s western boundary, but this is the first time the base has relied on sheep and goats. 

“We chose sheep and goats for several reasons,” said Wilson.  “First, they are smaller and more agile and will more readily utilize forage on the slopes and hillsides in Castle Terrace that cows would be unlikely to use.   Additionally the Castle Terrace area does not have the infrastructure to support cattle grazing at this time.”

Unlike cattle, which prefer grasses, goats prefer woody stems and leaves from shrubs and trees as well as grasses and flowers.  Sheep prefer small flowering plants, like the California poppy.

Also, goats and sheep provide different benefits than cattle.  Not only do they eat grasses and shrubs, they create less soil compaction and allow for contract grazing over short periods of time with a large number of animals, said Wilson. 

The natural resources office has used grazing as an effective land management tool since 1977, said Penn Craig, 60th Civil Engineer Squadron natural resource manager.

“Grazing promotes native species diversity and improves habitat for federally listed species by reducing grass heights, reducing dead plant material and increasing the amount of time wetlands remain filled with water,” said Craig.  “Additional allowing animals to graze the property reduces fire hazards and eliminate mowing costs.”

A shepherd and trained sheep dog will herd the animals around the 20-acre site until the vegetation is about 3 inches tall, said Wilson.  A portable electric fence will contain the animals in the evening and provide 24/7 oversight and protection.   A chain link fence also surrounds the area. 

“The electric fence is safe for small animals like rabbits and squirrels because the bottom fence is not electrified,” said Wilson. “Birds landing on the wire will not be shocked either because they are not grounded to anything.”        

The fencing does not use continuous electric current, only intermittent pulses, said Wilson.

“Also, the amperage is kept very low in electric fencing, which regulates the amount of electricity delivered.  The shock will be unpleasant, but not lethal,” she said. 

The smell typically associated with goat and sheep herds should not be a problem since the contractor is not using male goats, known as billys, which give off scent during breeding season. 

During grazing periods, housing residents should keep children and pets away from the chain link fence and keep dogs inside to avoid stressing the herd.  

The public is invited to see the goats as long as they remain outside the chain link fence. 

The goats and sheep will leave the base, tentatively, May 23. Balfour Beatty Communities will notify housing residents of any updates, said Wilson.