PRARIE DOGS AND TEH GRASSLANDS OF SOUTHERN ARIZONA
Background: Early in the 20th century, the valleys of southern Arizona were filled with tall grasses, which attracted cattle ranchers. Summer rainfall on the mountain ranges washed down into the valleys and permeated the soil, nourishing the grasslands. In the late 1800s, the ranchers had steadily killed off large predators, such as wolves, mountain lions, coyotes, and eagles. By the early 1900s, hundreds of thousands of prairie dogs lived in vast underground “towns” (interconnected tunnels and burrows) throughout the grasslands. Prairie dogs are social, very active animals, constantly digging and moving their tunnels. They kept the soil soft and porous, and filled with numerous holes. Grazing cattle would fall in the holes, break a leg, and die, leading to the ranchers’ collective decision to remove the prairie dogs.
Ralph Morrow was a game warden who received permission and assistance from the U.S. federal government to trap and poison the prairie dogs east of the Chiricahua Mountains. Within 10 years, he had removed the prairie dogs from this area. By the 1930s, the grasslands were gone as well, replaced by desert scrub vegetation. Summer floods were eroding large gullies, and the topsoil was gone, leaving hard-packed sandy clay with little organic matter.
Case: A group in Idaho is interested in eliminating prairie dogs because it is trying to farm buffalo commercially. The group members have come to your agency, which does environmental research and recommends strategies for remediation of local problems. Write a report detailing the ecological events relating to the extermination of prairie dogs east of the Chiricahua Mountains, and explaining what happened to change the area so dramatically. Make sure to consider the following in your report: