Habitat loss is a clear threat to a plethora of species, including the Richardson’s ground squirrel. This particular species, however, has recently demanded preventative-measure research as these squirrels are notorious for triggering false alarms at a United States nuclear missile base in Montana.
In the northern U.S., Richardson’s ground squirrels live in colonies that require burrows for protection, hibernation, and other necessities. These underground tunnels, which can penetrate metal and concrete barriers, greatly vary in length and width—occupying spaces up to 50 feet long and 6 feet deep.
Perfectly within the optimal living range of this ground squirrel is Malmstrom Air Force Base, Montana which is home to over 100 Minuteman III intercontinental ballistic missiles, each of which contains a nuclear warhead.
According, to MISSILE THREAT, a project of the George C. Marshall and Claremont Institutes, each one of these minuteman missiles can be loaded with at least 300 kT nuclear. A warhead magnitude 15 times that of which the U.S. dropped on Japan.
While this rodent does pose as a security concern—as deemed by triggering the motion detectors near the underground silos—stringent processes make accidents of a nuclear level highly unlikely. Instead the squirrels destroy some of the silo infrastructure and nibble on wiring.
Above anything else though, co-occupying this region with the ground squirrel comes at the expense of time and resources such as fuel. After all, the missile silos are dispersed across 23,000 square miles and each security threat needs to be cleared.
To alleviate this pain, the Department of Defense reached out to the National Wildlife Research Center for assistance on how to keep the Richardson’s ground squirrel out of silo territory.
Using a laboratory setting, Gary Whitmer simulated the Air Force base’s predicament—a metal fence, ground squirrels, and a desire to cross said gate (food). All the while, each fence was lined with a different material to see which was the least penetrable from not only underground but also aboveground.
Of the materials tested, the Center found two materials the squirrels had trouble climbing over atop the soil: clear hard plastic and electric tape. Similarly, they found two effective belowground barriers: small mesh expanded metal and pea gravel filled trenches.
After further studying ensued—this time in the field—the choices of barriers were narrowed allowing for scientist to carry on with specific simulations and to now understand why the obstacles were effective at excluding Richardson’s ground squirrels.
Clear sheets of polycarbonate plastic were too slippery for the rodents to scale and were thus effective aboveground. Pea gravel trenches accomplished the job belowground, as the ground squirrels could not burrow though a collapsible material and thus didn’t bother trying.
After further successful field studies, the Center plans on implementing said barriers on the nuclear missile base. Thus allowing the 341st Missile Wing Air Force personnel stationed at Malmstrom to focus more on matters of national security and leave habitat competition and loss to the scientist at the Natural Wildlife Research Center.
Works Cited: Article by Joseph Stromberg at http://blogs.smithsonianmag.com/science/2013/08/how-one-nuclear-missile-base-is-battling-ground-squirrels/