Mammals 105

Chapter 1

The Rodents - Chipmunks

Remember that old jingle? “Everybody doesn't like something, but nobody doesn't like Sara Lee”? Well, Chipmunks are the rodent that nobody doesn't like – except maybe pondbuilders. The genus Tamias, which means “treasurer” or “steward” in reference to their habit of storing seeds, includes one eastern species and 23 western Chipmunks, all North American except for a single Asian species. Alvin’s favorite little squeakers build underground den and sleeping areas, expansive burrows sometimes twelve to fifteen feet in length, with special “toilet tunnels” to isolate wastes and nutshells, keeping their sleeping areas clean and tidy. Problems arise when their tunnels intersect our liners, usually well below water level, to the detriment of both. (Can’t you just hear the triple squeak, “TSUNAMI!?) So, if you’ve got a leak, and you’ve seen these little guys in your rockwork, you should probably suspect the worst. Chipmunks have been known to chew right through multiple layers of geotextile and the EPDM lining below, creating devastating leaks that can be difficult to locate. Still, no matter what the provocation, we don't seem to want eradicate them, in stark contrast to the way we feel about, and deal with, their many rodent cousins - mice, rats, gophers, muskrats, nutria, beavers and the rest of the clan. It's not that Chipmunks don't cause damage, they’re just too cute to kill.

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Eastern Chipmunks hibernate in the winter and only pose a summertime threat to liners, while western species do not hibernate, so they are potentially a year-round problem. However, let’s not dwell just on the negative. Like most supposed “pests”, Chipmunks are actually good to have around. Their harvesting and hoarding of seeds and nuts plays a critical role in distributing new seedlings, and they consume many varieties of fungi, including those involved in symbiotic mycorrhizal associations with trees, the most famous of which is the fungus we call the truffle, which depends on rodents for spore dispersal. Forget “pearls before swine”, how about “truffles behind Chipmunks”!

To completely eliminate the potential for Chipmunk damage, you really have to begin during the installation of the water feature, it’s almost impossible to deal with Chipmunks after the pond has been completed. If you know that there are rodents in the area, it’s relatively easy to thwart their burrowing activities with a layer of hardware cloth, a lightweight welded galvanized wire fencing that comes in a variety of sizes. For Chipmunk deterrent, the quarter-inch size works best. The factory edges are safe for your liner but remember that everywhere you cut the roll of hardware cloth you are creating a potential sharp edge that could damage your liner. Clip the wires very close to the weld to avoid creating any extra sharp points, and bend all edges down and away from the liner material. The hardware cloth bends very easily and will conform to any excavation. Line your excavation with a layer of quarter-inch hardware cloth and cover with a layer of underlayment before installing the waterproof lining. This defensive structure will stop the most active of chipmunks from burrowing through your liner from below.