What Do Pronghorns Eat? A Look at Their Diet

Pronghorns are overwhelmingly forb and shrub eaters, not grass grazers, despite living in some of the grassiest landscapes in North America. Across seasons and regions, forbs (broad-leaved flowering plants like wildflowers and clover) typically make up the largest share of a pronghorn’s diet, followed by shrubs such as sagebrush. Grasses rarely contribute more than a small fraction. That basic preference holds whether the animal lives in open grassland or sagebrush steppe, which makes the pronghorn something of an oddball among the large herbivores that share its range.

Forbs and Shrubs Make Up the Bulk

A DNA barcoding study of pronghorn diets across multiple subpopulations found that forbs accounted for roughly 52 to 60 percent of what pronghorns ate, with shrubs coming in second at about 23 to 28 percent. Grasses (called graminoids in the research) made up only about 9 to 16 percent, and legumes filled in the remainder at around 6 to 10 percent.¹ The protein pronghorns extract from their diet follows a similar pattern: forbs provided between roughly a third and nearly two-thirds of dietary protein, while grasses contributed anywhere from a negligible amount up to about 43 percent depending on the season and subpopulation.¹

These numbers reinforce what decades of field observation have shown: pronghorns are essentially browsers. Even though grasses can make up nearly 80 percent of the vegetation available in a grassland setting, pronghorns still choose forbs and shrubs first. In grasslands, grasses make up only about 19 percent of their diet; in sagebrush steppe, that drops to around 7 percent.² Pronghorns maintain essentially the same preference ranking regardless of habitat type: forbs on top, shrubs next, grasses last.

Seasonal Diet Shifts

While forbs are the clear favorite overall, pronghorn diets shift substantially with the seasons. A study examining pronghorn and gemsbok diets in the American Southwest found that during the cool, dry season, shrubs dominated pronghorn diets at about 65 percent. When the warm, dry season arrived, forbs surged to roughly 65 percent of the diet, and they stayed high at around 54 percent during the warm, wet season.³ The pattern makes intuitive sense: forbs are lush and nutritious when growing conditions are good, but they die back or go dormant in winter, pushing pronghorns to rely more heavily on woody shrubs that remain available year-round.

Drought throws another wrench into the equation. When drought conditions hit, the same study found that shrubs climbed back to about 51 percent of the pronghorn diet, even outside the cool-dry season.³ Forbs are more sensitive to water availability than many shrubs, so when rainfall drops, the forbs that pronghorns prefer simply are not there. Shrubs become the fallback, and pronghorns are well adapted to switch. This flexibility is a survival tool: in the arid and semi-arid landscapes where pronghorns live, conditions can change fast, and a rigid diet would be a liability.

The Plants Pronghorns Favor

Within the broad categories of forbs and shrubs, certain species stand out as pronghorn staples. Sagebrush, especially big sagebrush, is one of the most important shrubs in the pronghorn diet across much of their range. In Yellowstone, researchers documented that pronghorns ate more big sagebrush over time as the ungulate community grew and competition for food intensified.⁴ Sagebrush is a chemically defended plant, loaded with volatile terpenes and other compounds that deter many herbivores, but pronghorns handle it well. In Wyoming’s Red Desert, sagebrush can dominate pronghorn diets altogether.⁵

Rabbitbrush is another shrub pronghorns turn to, and it becomes especially important when habitat fragmentation or degradation has altered local sagebrush communities. When their preferred shrubs are depleted or removed, pronghorns can shift to entirely different chemically defended plants like rabbitbrush as a substitute.⁵ Fringed sage and saltsage are other species that show up in pronghorn diet analyses, though their importance varies by location and by year. In the Yellowstone data, pronghorns ate less saltsage in the later study period while increasing their intake of big sagebrush, suggesting some degree of dietary reshuffling in response to changing conditions on the range.⁴

Among forbs, the picture is more diverse and harder to pin to a few flagship species. Pronghorns sample broadly from whatever forbs are available and in good condition. The DNA barcoding study that identified 137 distinct plant species in pronghorn diets gives a sense of just how varied their forb intake is.¹ They are not specialists honing in on a handful of forb species. They are generalist browsers sampling broadly from the forb community available to them, and the specific species in the mix change with geography, season, and growing conditions.

A Browser with Teeth Built for Grass

One of the genuinely puzzling things about pronghorn biology is that their teeth do not match their diet. Pronghorns have extremely hypsodont molars, meaning tall-crowned teeth that are typically associated with grazing animals. Tall crowns are an adaptation for grinding gritty, abrasive grasses: grass contains silica phytoliths that wear teeth down fast, and tall crowns give a grazer more tooth to burn through over a lifetime. You see the same dental design in horses, bison, and other committed grass eaters.

Yet pronghorns barely eat grass. Research reviewing both the modern diet data and the evolutionary record has noted this mismatch explicitly, describing extant pronghorns as “essentially browsers despite the extreme hypsodont nature of their molar teeth.”² One possible explanation is that the teeth are a holdover from an evolutionary past when pronghorn ancestors ate more grass. The antilocaprid family has deep roots on the North American plains, stretching back millions of years through a lineage of now-extinct species, and it is plausible that grass played a bigger role in earlier chapters of that history. But the modern pronghorn, the last surviving member of a once-diverse family, has settled firmly into a browsing niche.

Another explanation that biologists have raised is that dust and grit in arid environments can wear teeth down much like silica in grass, so hypsodont teeth might serve pronghorns well even on a forb-and-shrub diet simply because they live in dusty, wind-scoured habitats. Either way, the lesson is that dental anatomy does not always tell you what an animal eats today; it sometimes tells you what pressures shaped its lineage over deep time.

How Diet Shapes Water Needs

Pronghorns live in country where free-standing water can be scarce, and their diet plays a direct role in how much drinking water they need. A study in a semi-arid Arizona grassland ecotone found that pronghorn use of free water sources was negatively related to the moisture content of their forage: the juicier the vegetation, the less pronghorns visited water sources.⁶ When forage succulence was above roughly 75 percent water, no pronghorn visits to monitored water sources were recorded at all. That suggests pronghorns can meet their hydration needs entirely from the plants they eat when conditions are right.

This is a meaningful survival strategy in the arid West. During the warm, wet season, when forbs are abundant and full of water, pronghorns may have no need to seek out streams, ponds, or stock tanks. But during drought or winter, when forage dries out and shrub moisture drops, pronghorns become more dependent on free water. Wildlife managers who work with pronghorn habitat pay close attention to this relationship, because losing a water source in a landscape with dry forage can create a real bottleneck for a local herd.

Why Diet Quality Matters for Fawn Survival

Diet is not just about keeping an adult pronghorn alive. The quality of what a doe eats during pregnancy and nursing has measurable consequences for her fawns. A study examining pronghorn fawn survival in Idaho found that fawn body mass index, lagomorph abundance (a rough indicator of habitat productivity), and a marker of diet quality were all positively linked to fawn survival. The survival model built from these variables carried overwhelming statistical weight, and the authors concluded that higher-quality forage for does leads to heavier fawns, which in turn have the best chance of making it through their first vulnerable weeks.⁷

Pronghorn fawns are born small, and predation pressure on newborns is intense. Coyotes, golden eagles, and bobcats all take fawns, and a fawn’s best defense is to grow quickly and gain the speed it needs to escape. Heavier fawns born to well-nourished does reach that threshold sooner. So when forb availability drops because of drought, overgrazing, or habitat conversion, it is not just the adults who feel it: fawn recruitment declines, and the population can slide. Management actions that protect or restore high-quality forb habitat have a direct line to pronghorn population health through this fawn survival pathway.⁷

Sharing the Range with Other Herbivores

Pronghorns share their habitat with elk, bison, mule deer, and bighorn sheep across large parts of their range. Despite this overlap, most of these species do not compete heavily with pronghorns for food, because pronghorns eat a fundamentally different set of plants. In Yellowstone, researchers tracked diets and niche overlap among all five of these ungulates over two study periods spanning about 20 years. Of all the possible species pairings, only two showed statistically significant dietary overlap: elk with bighorn sheep, and mule deer with pronghorn.⁴

The mule deer-pronghorn overlap makes sense: both species lean toward browsing rather than grazing, and both eat sagebrush and forbs. Mule deer in the Yellowstone study were eating more fringed sage and rabbitbrush in the later period, plants that also appear in pronghorn diets. This overlap could become more consequential if either species’ population grows or if shrub habitat shrinks. But for now, pronghorns generally partition the food supply well enough that outright competitive displacement is rare. Bison and elk, the dominant grass eaters in these systems, are eating something pronghorns largely ignore, so their massive population increases had little direct effect on pronghorn diet quality.

How Fences Cut Off Food

One of the most significant practical barriers between pronghorns and the food they need is fencing. Pronghorns are fast runners but poor jumpers. Unlike deer, which clear standard fences with ease, pronghorns prefer to pass under or through fences, and many fence types simply block them. This is not just an inconvenience. Research in the northern sagebrush steppe found that both migratory and resident pronghorns strongly avoided areas with high fence density. Modeling predicted that if all fences were removed from the landscape, the area of high-quality pronghorn habitat would increase by 16 to 38 percent. Conversely, doubling fence density decreased high-quality habitat by up to 11 percent and increased low-quality habitat by 13 to 21 percent.⁸

The type of fence matters enormously. Woven wire fencing, the kind with a tight mesh from top to bottom, is essentially impenetrable to pronghorns and dramatically reduced their ability to cross. Standard barbed-wire fences with a low enough bottom strand are more passable, though still not easy. Research found that woven wire fences substantially reduced pronghorn crossing rates and increased the time animals spent trying to get through compared to strand fences with a low bottom wire.⁹ For a species that seasonally migrates to track forage availability, being locked out of portions of the landscape by fencing can mean being stuck with inferior food during a season when better options exist just on the other side.

Wildlife-friendly fence modifications, such as raising or removing the bottom wire or replacing woven wire sections with smooth bottom strands, have gained traction in pronghorn country. The science supports their effectiveness: reducing fence density or improving fence permeability expands the effective range pronghorns can use and the forage they can reach.⁸ Several state wildlife agencies and conservation groups now invest in fence modification projects specifically to benefit pronghorn movement and access to seasonal forage.

The Gut Behind the Diet

Pronghorns are ruminants, equipped with a multi-chambered stomach and a microbial community that ferments plant material before it reaches the true digestive tract. Like cattle, sheep, and deer, they rely on gut microbes to break down the cellulose, tannins, and other tough plant compounds that a simple stomach cannot handle. But the specific composition of a pronghorn’s gut microbiome reflects its unusual diet. Research from Wyoming’s Red Desert has linked pronghorn gut microbiome composition to life history traits, suggesting that the microbial community is tuned to the particular mix of sagebrush, forbs, and other chemically defended plants that pronghorns eat.⁵

Sagebrush in particular poses a digestive challenge. Its volatile terpenes are toxic to many herbivores and can inhibit microbial fermentation in the rumen. Sage-grouse, which also rely heavily on sagebrush, have evolved specialized detoxification pathways. Pronghorns appear to manage the challenge through some combination of microbial adaptation and dietary mixing: by eating sagebrush alongside forbs and other shrubs, they may dilute the terpene load enough to keep fermentation running efficiently. The ability to shift between chemically distinct shrub species, from sagebrush to rabbitbrush and back, points to a digestive system flexible enough to handle a rotating cast of plant defenses.

When Pronghorns Cannot Find What They Need

The combination of drought, habitat conversion, and physical barriers like fencing creates situations where pronghorns simply cannot access adequate forage. Sagebrush ecosystems across the western United States have been under pressure from energy development, invasive annual grasses like cheatgrass, and wildfire cycles that remove shrub cover faster than it can regenerate. When sagebrush is lost, pronghorns lose both a winter staple and cover, and the replacement vegetation, often dominated by cheatgrass, offers almost nothing of nutritional value to them. Cheatgrass greens up early, cures fast, and provides neither the protein nor the moisture pronghorns get from their preferred forbs and shrubs.

Agricultural conversion presents a different dynamic. In some areas, pronghorns will feed on alfalfa and other crop fields, particularly in fall and winter when native forage is depleted. This can bring them into conflict with landowners. But agricultural fields are not a reliable substitute for native forb and shrub habitat, because they are seasonal, they come with disturbance from machinery and people, and they lack the diversity of nutrients that a wild plant community provides. Pronghorns using cropland are typically responding to a shortage of their natural diet, not choosing an upgrade.

The cumulative picture from the research is that pronghorn diets are flexible but not infinitely so. They can switch among forbs, shrubs, and even grasses as conditions shift, and they can tolerate chemically defended plants that stymie other herbivores. But they depend on a functioning shrub-steppe or mixed-grass ecosystem that provides those options. When that ecosystem is degraded past a certain point, the pronghorn’s dietary flexibility runs out, and population consequences follow, most visibly through declining fawn survival and reduced adult body condition.

1
PubMed Central. Seasonal shifts in pronghorn antelope (Antilocapra americana) diets under a new lens: Examining diet composition using a molecular technique
2
Palaeogeography, Palaeoclimatology, Palaeoecology. Was grass more prevalent in the pronghorn past? An assessment of the dietary adaptations of Miocene to Recent Antilocapridae
3
Wildlife Biology. Diet composition, quality and overlap of sympatric American pronghorn and gemsbok
4
Canadian Journal of Zoology. Niche relationships within a guild of ungulate species in Yellowstone National Park, Wyoming, following release from artificial controls
5
PLOS ONE. Relating gut microbiome composition and life history metrics for pronghorn (Antilocapra americana) in the Red Desert, Wyoming
6
ResearchGate. Use of water sources by pronghorn in a semi-arid Arizona grassland ecotone
7
The Journal of Wildlife Management. Factors Influencing Survival Rates of Pronghorn Fawns in Idaho
8
Ecosphere. Fences reduce habitat for a partially migratory ungulate in the Northern Sagebrush Steppe
9
Ecosphere. Fence types influence pronghorn movement responses