The Bronx Zoo in New York City had tried prairie dogs and still had the jitters from the experience. Their dogs had promptly dug out of the enclosure and spread over the zoo. They hired a trapper who spent a whole summer trapping prairie dogs. The National Zoo in Washington suggested galvanized chicken wire buried in the ground. Clapp experimented with the wire, but still escapes were common. Small volcanoes of earth would appear outside the fence. Ranchers and farmers reported new dog diggings from one to three miles away. Prairie dog stock sank to zero.
Experimentation finally proved that the best fencing was heavy steel mesh, 30 inches above ground and 18 below. It seems that a prairie dog will dig under a wall, but when it meets a mesh wire it becomes nonplused and digs elsewhere.
"Very seldom have any of our dogs tunneled under the 18-inch underground fence," Clapp said. "But don't sell prairie dogs short on brains. They're smart."
The fencing problem led Clapp into a lengthy study of the life and times of the prairie dogs. As the city of Lubbock grew, he made friends with construction men digging cellars for the new buildings. When their power shovels encountered old dog diggings, they would notify him. Armed with pencil and pad he'd get down into the excavation and make diagrams of the holes of dogs of long ago.
His activities caused considerable concern among his friends. Occasionally some oldtime cattleman would lean over the edge and yell, "Clapp, what in the hell are you doing down in that hole?"
"Some of them thought I was half-crazy," Clapp said, "and there were others who thought I was all crazy."
Several dogs paused in their feeding while the mayor laughed again.
"Well, I drew the profiles of more than 150 dogholes," he resumed. "And I learned plenty."
His researches disclosed that a prairie dog home is an L-shaped burrow descending almost vertically from 12 to 20 feet and then horizontally from six to 15 feet. Three to six feet below the surface, there is a small room which Clapp calls the "barking room and turntable." When alarmed, the prairie dog dives into his hole and barks defiance from the safety of this room. If the enemy appears at the mouth of the hole the prairie dog dashes to even safer depths.
The horizontal branch of the burrow rises somewhat, and above it there is a cavern which contains the grass-lined nest. There is also a long tunnel slanting to the surface, but this appears to be used only during construction. In completed burrows it is usually filled with dirt and trash. There may be other rooms formerly used as nests and then filled with dirt when a new nest is built. Clapp found only two dogs' homes that had more than one entrance.