While creating my chipmunk character this winter, I have learned a whole lot about their natural history and behavior. My research has extended underground, even. I’m fascinated with the practical organization of their burrow systems, which can become quite complex over many years.
Back when I was at RISD I made a gouache illustration of a chipmunk burrow, which I don’t care for now – I can do much better. But I noticed it gets lots of hits on my website, so why not update it? This new image, which is entirely digital (Photoshop), maps out a typical burrow of an eastern chipmunk. My primary reference was a study called “Social Behavior and Foraging Ecology of the Eastern Chipmunk (Tamias striatus) in the Adirondack Mountains,” by Lang Elliot, and published by the Smithsonian Institution in 1978. He carefully excavated chipmunk burrows and described their structures, contents, and the chipmunks’ behaviors inside and around the burrows. It was a lot to process – my illustration is an example of a simple burrow layout. I have not included measurements, since those depend on so many environmental factors and would over-complicate this image.
The burrow consists of a series of tunnels of varying widths, and may follow alongside large tree roots. Side pockets are used to hoard food like nuts and seeds, collect empty shells, and sometimes as extra space to turn around when space gets tight. Centrally located is the nest chamber, which is lined with crunched up dry leaves – cozy! Narrow tunnels extend downward in places to draw water away from the burrow. The chipmunks tend to excavate these into the dense layer of hardpan, which doesn’t absorb water well, so sometimes water can collect at the bottom of these drainages. In his report, Elliot noted that he did not find a designated “bathroom” area in the burrow, so the chipmunks probably do their business outside. To get outside, there are several entrances. Some might be plugged up temporarily or decommissioned permanently. A plunge hole refers to an opening that leads straight down. More complex burrows can have alternate/escape entrances.