Grasslands are defined by what they lack: trees. Without a forest canopy, there are no tree hollows to nest in, no branches to perch on, and no shade to hide under. Animals living in these open landscapes face relentless sun, extreme temperature swings, and exposure to predators with clear sightlines. Burrowing underground and living at ground level aren’t just common strategies in grasslands. They’re the most logical solutions to every major survival problem the habitat presents.
No Trees Means No Alternatives
In forests, animals distribute themselves vertically. Squirrels nest in tree cavities, birds roost on branches, and primates sleep in the canopy. Grasslands compress almost all animal life into two dimensions: the surface and below it. With few or no trees to offer shelter, elevation, or nesting sites, animals must find protection in the ground itself or adapt to life on it. This is the simplest and most fundamental reason burrowing mammals and ground-nesting birds dominate grassland ecosystems.
The evolutionary roots of this pattern run deep. When the asteroid impact 66 million years ago wiped out the dinosaurs, it also destroyed forests worldwide. Research published in Current Biology found that every lineage of birds that survived that extinction event was non-arboreal. Tree-dwelling birds simply couldn’t persist without trees. The ground-dwelling survivors later diversified into the enormous range of bird species alive today, but the lesson holds: when tree cover disappears, ground-adapted species thrive. Grasslands, which expanded dramatically over the past 20 to 30 million years as climates dried, have been selecting for ground-based lifestyles ever since.
Burrows Solve the Temperature Problem
Grasslands experience some of the most extreme temperature swings of any habitat. Without tree cover to buffer sunlight and wind, surface temperatures can be brutal. Data from simulated rodent burrows in California grasslands showed that above-ground temperatures reached as high as 51.8°C (125°F) in summer, while burrow temperatures generally stayed between 35 and 40°C (95 to 104°F). In winter, the pattern reversed: above-ground air dropped to nearly negative 10°C (14°F), while burrows stayed between 5 and 10°C (41 to 50°F), consistently 7 to 15 degrees warmer than the surface.
The key advantage isn’t just that burrows are cooler in summer and warmer in winter. It’s the stability. Above-ground temperatures swing wildly over the course of a single day, rising sharply as the sun climbs and plummeting after dark. Burrow temperatures remain relatively flat throughout the day. For small mammals like prairie dogs, ground squirrels, and pocket gophers, this stability is critical. Small bodies lose and gain heat quickly, making them vulnerable to both overheating and hypothermia. A burrow acts as a natural thermostat, buffering those dangerous extremes with very little effort from the animal.
Hiding in Plain Sight
Predators in grasslands have excellent visibility. Hawks, eagles, and falcons patrol from above, while coyotes and foxes scan flat terrain with few obstructions. For prey animals, the options are limited: run fast, go underground, or blend in.
Burrowing animals solve this by disappearing entirely. A prairie dog that ducks into its tunnel network is essentially invisible, and the burrow’s narrow entrance makes it difficult for larger predators to follow. Ground-dwelling birds take the camouflage route instead, and the results are remarkably precise. A study in Scientific Reports found that clutch survival for ground-nesting plovers and coursers depended directly on how well egg coloring matched the surrounding ground. Nests where eggs had low contrast against a low-contrast background survived at higher rates, and nests where high-contrast eggs sat on high-contrast backgrounds did too. The match between egg and environment predicted survival more reliably than other factors.
Different species use different versions of this strategy. Plovers and coursers flee their nests when a threat approaches, sometimes from more than 60 meters away, leaving their camouflaged eggs to avoid detection on their own. Nightjars take the opposite approach: they sit perfectly still on the nest, relying on their own plumage to blend into the ground. For nightjars, survival depended on how well the incubating bird’s feather patterns matched the background, not the eggs. Both strategies work because grassland ground cover, a mix of dried grasses, soil, and low vegetation, provides excellent camouflage material for species adapted to match it.
Food Concentrates at Ground Level
Grasslands pack their food resources close to the earth. The grasses themselves are the most obvious food source, feeding everything from bison to grasshoppers. Seeds drop to the ground and accumulate in the soil and leaf litter, providing reliable nutrition for ground-foraging birds like quail, larks, and sparrows. Roots and tubers sit just below the surface, accessible to burrowing species.
The insect supply is equally ground-centric. Global estimates put the number of soil-dwelling arthropods at roughly 10 quintillion individuals, with about 95% being soil mites and springtails. These tiny invertebrates represent an enormous biomass concentrated in the top layers of soil, roughly 200 million metric tons of dry weight worldwide. Above-ground arthropods tend to be larger individually but exist at far lower population densities. For insect-eating birds like meadowlarks and killdeer, foraging on or near the ground in grasslands puts them right where the food is densest. There’s little reason to be up in a canopy that doesn’t exist, chasing insects that are more abundant underfoot.
Grassland Soils Are Easy to Dig
Not all ground is worth burrowing into. Forest floors are often tangled with dense root networks from trees, making excavation difficult. Rocky or waterlogged soils present their own problems. Grassland soils, by contrast, tend to be deep, well-drained, and held together by fibrous grass roots that stabilize tunnel walls without making them impossible to dig through.
The dominant soil type in many of the world’s great grasslands is rich in organic matter from centuries of decomposing grass roots. This creates a soil that’s firm enough to hold a burrow’s shape but soft enough for animals to excavate with claws or teeth. The result is a habitat where burrowing is physically practical in a way it simply isn’t in many forests, deserts, or wetlands.
Burrowers Reshape the Grassland Itself
Once burrowing animals establish themselves, they change the ecosystem in ways that reinforce grassland health and support even more ground-dwelling species. Prairie dogs are a well-studied example. Their tunneling aerates compacted soil, redistributes nutrients from deeper layers to the surface, and adds organic matter from nesting material and waste. One of the most measurable effects is on water infiltration. In semiarid grasslands, prairie dog colonies showed water infiltration rates of about 357 millimeters per hour, compared to 283 mm/hr in grasslands without prairie dogs and just 97 mm/hr in shrubland that had replaced former grassland.
Soil carbon storage was also higher in prairie dog grasslands than in either uncolonized grasslands or shrublands. These aren’t minor differences. When prairie dog populations decline, the research shows that the ecosystem itself degrades, trending toward desertification. The burrows also serve as shelter for dozens of other species that don’t dig their own, including burrowing owls, black-footed ferrets, rattlesnakes, and various insects. A single prairie dog town functions as an underground apartment complex for the broader grassland community.
This feedback loop is part of why grasslands are so strongly associated with ground-level animal life. The habitat favors burrowers and ground-dwellers, and those animals, in turn, maintain the soil conditions and open structure that keep the grassland functioning. It’s a self-reinforcing system shaped by millions of years of coevolution between the land and the creatures that live on and under it.