Beavers may be the poster children for ecosystem engineers, but other rodents also deserve some acknowledgement for their roles in shaping habitats.
Consider the muskrat. Like beavers, muskrats are known to create dome-shaped lodges out of things like twigs and leaves. But this isn't their only method of building shelters. Muskrats who live alongside rivers, ponds or ditches tend to eschew lodges in favor of deep holes they've burrowed into the banks. The critters begin by diving under the water, where they start working on a tunnel about 6 to 18 inches (15.2 to 45.7 centimeters) below the surface. From there, the muskrats dig farther and farther at an upward slant. Eventually, they produce a warm, dry living chamber that's only accessible through underwater entrances. Not a bad way to keep uninvited guests out.
Such burrows can have big implications for the waterways they're connected to. For one thing, the structures promote erosion, which can cause banks to collapse. This prompts water to race into the afflicted area, disrupting the river flow. Over time, if enough water is re-routed toward the collapsed bank, the river's curvature might change — thanks partly to the rodents. And much to the annoyance of human land developers, when a muskrat burrows into a manmade dam, unwanted drainage often follows.