# Burrow Dimensions of Ground Squirrels, with Special Reference to the California Ground Squirrel

> How far does a ground squirrel dig? Reviewing nearly a century of measurements, researchers found that most California ground squirrel burrows are under 10 metres long, but the species also holds the records: one system ran 226 metres with 33 entrances and housed 11 adults. Bigger and more social species dig longer burrows, which matters to anyone managing squirrels on flood levees.

Summary by Kersey Lawrence, Original Wisdom. Updated 9 November 2026. Page: https://www.originalwisdom.com/tracking-literature/2012-van-vuren-ordenana-burrow-dimensions-ground-squirrels/

## Citation and access

- **Authors:** Dirk H. Van Vuren and Miguel A. Ordeñana
- **Year published:** 2012
- **Journal or source:** California Levee Vegetation Research Program report, University of California, Davis
- **Full citation:** Van Vuren, D. H. and Ordeñana, M. A. 2012. Burrow dimensions of ground squirrels, with special reference to the California ground squirrel. California Levee Vegetation Research Program report (27 February 2012). Department of Wildlife, Fish, and Conservation Biology, University of California, Davis. Funded by the California Department of Water Resources (Contract No. 4600008761) and the Sacramento Area Flood Control Agency (Contract No. 984). 23 pp.
- **Access status:** Publisher link only
- **Where to find it:** https://search.worldcat.org/search?q=Burrow+Dimensions+of+Ground+Squirrels%2C+with+Special+Reference+to+the+California+Ground+Squirrel+Vuren

## Tags

- **Species:** Mammals > California ground squirrel
- **Region:** North America > United States
- **Behaviour and ecology:** Behaviour
- **Methods and technology:** Literature review
- **Data type:** Existing data; Review
- **Observer qualification:** Not needed
- **Discipline:** Behaviour and ecology; Human–wildlife conflict
- **Year published:** 2012

## Detailed keywords

- **Species:** Studied: California ground squirrel (Otospermophilus beecheyi), compared with 17 other North American ground-dwelling squirrels from published studies: black-tailed prairie dog (Cynomys ludovicianus), white-tailed prairie dog (Cynomys leucurus), Utah prairie dog (Cynomys parvidens), Gunnison’s prairie dog (Cynomys gunnisoni), Townsend’s ground squirrel (Urocitellus townsendii), Great Basin ground squirrel (Urocitellus mollis), Idaho ground squirrel (Urocitellus brunneus), Richardson’s ground squirrel (Urocitellus richardsonii), Wyoming ground squirrel (Urocitellus elegans), Belding’s ground squirrel (Urocitellus beldingi), Columbian ground squirrel (Urocitellus columbianus), Arctic ground squirrel (Urocitellus parryii), thirteen-lined ground squirrel (Ictidomys tridecemlineatus), Mexican ground squirrel (Ictidomys mexicanus), Franklin’s ground squirrel (Poliocitellus franklinii), golden-mantled ground squirrel (Callospermophilus lateralis) and white-tailed antelope squirrel (Ammospermophilus leucurus).
- **Location and habitat:** Focus on levees in the Sacramento Valley, California, United States. Record burrows from San Luis Obispo County and Fresno County, California. Comparison data from published studies of North American species.
- **Topics:** burrow length and depth; burrowing behaviour; nest burrows; burrow systems and entrances; body size; sociality and index of social complexity; soil type (sand, silt, clay, caliche layers); burrow age and enlargement over time; burrow inheritance; interconnected burrows at high density; levee integrity, “piping” of water, collapse and erosion; ground squirrel control.
- **Statistics or models:** Correlation analysis (correlation coefficient r; type not stated) between body mass and burrow length and depth, and between the index of social complexity (from Blumstein and Armitage 1997) and burrow length. Weighted averages across studies; midpoints of ranges used as means for two studies (Howell 1938, Turner 1973). Body mass from the midpoint of ranges in Reid (2006). Inconsistencies in the report: (1) Table 1 cites Haberman and Fleharty 1972, the literature cited gives 1971; (2) the text says the California ground squirrel values “agree” with Tracy Storer’s typical depth of 0.8 to 1.2 m, but the mean depth in Table 1 is 0.6 m; (3) Figure 1 gives N = 25 burrow lengths with three longer burrows not shown, while Table 1 gives 28.
- **Data type:** Existing data: a review of published burrow measurements (studies from 1918 to 2008), plus unpublished data provided by A. Berentsen. No new field data.

## Synopsis

### 1. What they did

Ground squirrels dig burrows for shelter from predators and bad weather, for raising young, for hibernation and as quick refuges. Where they live on levees, their burrows can let water seep through (“piping”), leave hollows that collapse, or speed up erosion. In California’s Sacramento Valley, the California ground squirrel is common on levees and is seen as a threat to them. To help levee managers judge that risk, the authors reviewed what is known about how long and how deep ground squirrel burrows are, and why.

- Gathering the measurements. They searched the literature for burrow length and depth of North American prairie dogs, ground squirrels and antelope squirrels. They used only typical nest burrows of adults, leaving out juvenile burrows, temporary refuge burrows and burrows reported as the longest or deepest found. Length was the total length of all tunnels; depth was the depth of the nest chamber, or else the deepest point. Some values were measured from scale drawings.

- Comparing species. They tested whether larger species dig longer and deeper burrows, and whether more social species dig longer burrows, using a published index of social complexity.

- Drawing on earlier work. They also gathered earlier findings on how soil and burrow age affect burrow size.

This report was prepared for the California Levee Vegetation Research Program.

### 2. What they found

Across species

- Mean burrow length ranged from 1.4 m (golden-mantled ground squirrel) to 26.1 m (Utah prairie dog). Mean depth ranged from 0.2 m (thirteen-lined ground squirrel) to 1.8 m (black-tailed prairie dog and Townsend’s ground squirrel).

- Length in particular varied a lot within species: for example 2.9 to 17.4 m in Great Basin ground squirrels and 3.7 to 29.3 m in white-tailed prairie dogs.

- Larger species dug longer burrows (r = 0.53, 17 species) and deeper burrows (r = 0.57, 18 species).

- More social species dug longer burrows (r = 0.71, 13 species).

- Burrow length and depth also went together (r = 0.56, 17 species).

California ground squirrels

- Burrow lengths ranged from 0.9 to 42.1 m, with a mean of 7.5 m and a median of 4.6 m; 79% were under 10 m long. Depths ranged from 0.2 to 1.7 m (mean 0.6 m).

- Some burrows were a short, nearly straight tunnel with one or two entrances and a nest chamber; others were a maze of tunnels with many entrances (one example had 13).

- California ground squirrels hold the records for both the longest and the deepest ground squirrel burrows ever measured. The longest, in San Luis Obispo County, totalled 226 m, had 33 entrances, displaced 2.8 cubic metres of soil and housed 11 adults (6 females and 5 males). The deepest, in Fresno County, went 8.5 m below the surface.

Soil and burrow age (from earlier studies)

- Burrows tend to be longer in soils that are easy to dig but firm enough not to collapse. Squirrels in sandy soil may dig just beneath a hard clay or caliche layer, which acts as a roof.

- New burrows are often shorter than established ones. Fresh soil at entrances shows burrows keep growing; Columbian ground squirrels were estimated to lengthen their burrows by 4 to 7 m a year.

### 3. What they concluded

- The wide variation is somewhat surprising given the high energy cost of digging, but squirrels often take over empty burrows or inherit them from relatives, so the cost may be spread over generations.

- At least four factors shape burrow size: body size, soil type, time (burrow age) and sociality.

- Larger squirrels likely need more underground space. Why they also dig deeper is less clear; tunnels slope down steeply from the entrance, so a longer system may also be a deeper one.

- Social species may dig bigger systems to house several residents. In less social species, long systems may arise when neighbouring burrows join up at high densities and the residents tolerate the connections.

- California ground squirrels have a low index of social complexity (0.26, the lowest in the study), and adult females are thought to live alone. Yet large shared systems have been found. These may form where dense aggregations (up to 90 adults per hectare) persist over time.

### 6. Other technologies, skills or innovations

- Burrow lengths were measured from published scale drawings where authors did not report them.

- A published index of social complexity (Blumstein and Armitage 1997) was used to compare sociality across species.

### 7. Implications for conservation (from the paper)

- California ground squirrels can dig right through a levee, although most burrows are far shorter than that. Short burrows on opposite sides of a levee can also come close to meeting, raising the risk of piping.

- Winding burrows and many burrows close together can leave hollows that are prone to collapse.

- Levees built from loose material dredged from the river bottom may be easy to dig, and harder layers inside a sandy levee may give squirrels a “roof”.

- The longer squirrels live on a levee, the bigger their burrows are likely to get. Burrows were shorter where squirrel numbers were regularly controlled (Berentsen and Salmon 2001). Populations that stay dense over time may produce longer and more interconnected burrows.

### 8. Implications for tracking (Original Wisdom's observations)

_These are Original Wisdom's observations, not the authors'._

- Burrows are among the most lasting signs an animal leaves. This report shows how much burrow size and shape vary within a single species, so what is seen at the surface (number of entrances, fresh soil at the mouth) may say little about the system below.

## Cite this summary

Lawrence, K. 2026. Summary of: Burrow Dimensions of Ground Squirrels, with Special Reference to the California Ground Squirrel (Van Vuren and Ordeñana, 2012). Original Wisdom, Tracking Literature. https://www.originalwisdom.com/tracking-literature/2012-van-vuren-ordenana-burrow-dimensions-ground-squirrels/