Documenting Prairie Burrow Entrances and Occupant Uncertainty

The short answer: who lives in prairie burrows?

On open Montana grassland, the holes you see are mostly dug by mammals. Common diggers include American badgers, ground squirrels, pocket gophers and black-tailed prairie dogs. Several other animals move into burrows that someone else dug. The best-known prairie bird example is the Burrowing Owl.

For field observers, that difference matters. The animal that dug a hole may not be the animal using it now. Entrance size, mound shape and habitat can suggest a likely digger. Only an animal actually seen entering or leaving, or clear fresh sign, tells you about current use. The tunnels and chambers below ground stay unseen either way.

Why animals use burrows

The National Wildlife Federation describes dens and burrows as shelters used for protection and for raising young. Animals may use them briefly or for long periods. Some animals dig their own burrows, and others reuse abandoned ones.

Prairie-dog mounds serve more than one purpose. They give the animals a raised lookout, help keep water out of the burrow and may help move air through it. That is why a prairie dog standing upright on a mound at a burrow entrance is such a familiar grassland sight.

Comparing entrances and mounds

The Montana Department of Agriculture's field rodent identification key gives the surface clues below. The key does not cover every species, and the size ranges overlap. Treat each row as one clue to weigh, not as a final answer.

Likely excavator	Entrance clues	Mound or soil clues
American badger	Round to oval opening, about 6–12 inches across	Large plume of excavated soil
Ground squirrel	Small opening, about 2–2.5 inches	Sometimes a small amount of excavated soil nearby
Pocket gopher	Opening often not the most obvious feature	Mounds that are fan-shaped or kidney-shaped
Black-tailed prairie dog	Usually about 5–8 inches; the key's photo caption gives a wider 4–12-inch range	Mounds at entrances, used as lookout points

An entrance of about 7 inches could fit both the badger range and the prairie dog range. When sizes overlap like this, look at other features: mound shape, soil spread, how many openings are grouped nearby and the surrounding habitat.

Reading the habitat

The Montana Field Guide links black-tailed prairie dog colonies with flat, open grassland or mixed shrub and grassland where vegetation is low and fairly sparse. Many entrances clustered on short, open ground point toward a prairie dog colony. A single large hole with a big soil plume in other cover points somewhere else. Habitat describes the setting; it does not confirm that any particular species is present at a particular site.

Signs that a burrow is in use

A 2019 Montana prairie dog management publication lists surface signs that can suggest whether a burrow is active:

• Possible activity: a smooth, maintained-looking opening; fresh droppings nearby; visible tracks.
• Possible inactivity: spider webs across the entrance; general disrepair; collapse.
• Possible Burrowing Owl use: feathers and white droppings at or near the entrance.

These signs support an interpretation but do not guarantee one. A web shows that nothing has passed through recently. It does not prove the burrow is permanently abandoned.

Burrowing Owls: the bird that moves in

The Montana Field Guide reports that Burrowing Owls in the state nest in abandoned prairie-dog, ground-squirrel and badger burrows in open grassland, and that they may modify those burrows. The account specifically records owls using badger holes in the Bozeman area.

Because the owls reuse burrows, an entrance that matches a badger or prairie dog by shape and size may hold an owl. Feathers or whitewash at an entrance shaped like a prairie dog burrow suggest that the owl moved in after the digger. They do not mean both species are using it at the same time.

Keep the excavator and the occupant separate

The U.S. Fish and Wildlife Service defines a mound as the material pushed out when a burrow is dug. Its 2014 Utah prairie dog survey protocol treats the original excavator and the current occupant as separate questions, and it includes a step for checking burrows whose origin is uncertain. Those Utah survey categories are not Montana identification rules. The underlying idea still applies to any field notes: record who probably dug the hole and who is using it now as two separate entries.

A field workflow

• Document only what is visible, and leave the entrance, mound and vegetation as you found them.
• Photograph the entrance and mound, and include a scale reference if you can.
• Compare several features with a regional reference rather than relying on size alone.
• Record the likely excavator, any signs of activity and any animal actually seen as three separate items.
• If you see the same burrow in use on later visits, log each sighting as more evidence. Do not treat a series of visits as a complete record of what has lived underground.

Sample recording worksheet

The template below is an original example built from the clues above. Fields describing underground chambers are left out on purpose, because they cannot be observed from the surface.

Observation ID:
Date / location:
Entrance shape:
Size estimate (and how estimated):
Mound shape:
Surrounding vegetation:
Opening condition (maintained, webbed, collapsed):
Photograph reference:
Animal seen entering or leaving (yes/no, species):
Possible excavator:
Possible current occupant:
Reference used for comparison:

Example: two burrows, no animals seen

This example is hypothetical. Burrow A has a mound and an opening that looks maintained. Burrow B has no visible mound and a web across its entrance. No animal was seen at either one.

A careful record notes the surface differences: mound present or absent, maintained opening or webbed opening. It leaves the current-occupant field unresolved for both burrows. Burrow A's condition suggests recent activity, and Burrow B's suggests no recent passage. Neither observation identifies who lives there.