According to Gram Research analysis, wolves in northwestern Portugal specialized heavily on free-ranging horses, with horses comprising 85-93% of wolf diet across two years. Researchers identified 39 individual horses killed by wolves using genetic analysis of wolf droppings and feeding sites, revealing that predation affected horses of all ages—from foals to adults—with juveniles representing 38% of kills.
Scientists in Portugal discovered that wolves are eating wild horses far more often than previously understood. By analyzing wolf droppings and tracking wolf movements with GPS, researchers found that horses made up 85-93% of what wolves ate in a two-year study. They identified 39 individual horses that wolves had hunted, including young foals and adult horses. This research shows that when wolves specialize in hunting horses, it can seriously affect wild horse populations and create conflicts between wolves and the people who own horses. The findings help scientists better understand how wolves and horses interact in nature.
Key Statistics
A 2026 research article published in Scientific Reports found that horses comprised 85% of wolf consumed biomass in 2017 and 93% in 2018 in northwestern Portugal, demonstrating strong dietary specialization on a single prey species.
Genetic analysis of wolf feeding sites and droppings identified 39 individual horses killed by one wolf pack, with juveniles accounting for 38% of predation events, foals for 12%, and adult horses for 50%.
Wolf GPS-tracking identified 19 feeding sites in Portugal, all containing horse remains, with 26% located within the wolf pack’s core territory, indicating horses were central to the pack’s survival strategy.
DNA analysis revealed that the 39 horses killed by wolves came from 10 of 14 family groups in the wild horse population, showing that predation affected multiple horse lineages across the region.
The Quick Take
- What they studied: How often wolves hunt and eat free-ranging wild horses, and what impact this has on horse populations in Portugal
- Who participated: Researchers tracked one wolf pack in northwestern Portugal over two years (2017-2018), analyzing wolf droppings, GPS tracking data, and genetic samples from 39 individual horses
- Key finding: Horses made up 85-93% of the wolf pack’s diet, and wolves killed horses of all ages—from young foals to adult horses—with juveniles being hit hardest at 38% of predation events
- What it means for you: If you live in areas with both wolves and wild horses, this research shows that wolf predation on horses is a real and significant problem that needs management strategies. However, this study is specific to one region and one wolf pack, so results may differ elsewhere.
The Research Details
Researchers used multiple detective methods to understand what wolves were eating. They collected wolf droppings and analyzed them for DNA to identify which horses the wolves had eaten. They also used GPS collars on wolves to track where they went and found 19 feeding sites where wolves had eaten horses. Finally, they collected genetic samples from wild horses and used DNA analysis to figure out which individual horses had been killed and whether they were related to each other. This combination of methods—like being a wildlife detective using both footprints and DNA evidence—gave them a much clearer picture than any single method could provide.
The researchers worked in northwestern Portugal where wolves and free-ranging horses live in the same area. They tracked one wolf pack over two years and carefully documented every horse they could identify from the wolves’ feeding sites and droppings. By comparing the DNA from horses found at wolf feeding sites with DNA from living horses in the area, they could figure out exactly which horses had been killed and whether they came from the same families.
This approach was important because it allowed researchers to see the real impact on horse populations. Instead of just guessing how many horses wolves eat, they could count actual individual horses and understand which age groups were most vulnerable. This kind of detailed genetic work is rare in wolf research and provides much stronger evidence than older methods.
Understanding what wolves eat is crucial for managing both wolf and horse populations. When wolves specialize heavily on one type of prey—in this case, horses—it can cause serious problems. Horse owners may lose animals, which creates conflict with wolf conservation efforts. At the same time, if wolves are eating mostly horses, scientists need to know whether this is sustainable or if it’s harming the wild horse population. This research provides solid evidence to help make better decisions about how to protect both species.
This study is strong because it uses multiple methods to verify findings rather than relying on just one type of evidence. The genetic analysis is particularly reliable because DNA doesn’t lie—researchers could definitively identify which horses were killed. The GPS tracking of wolves provided concrete locations of feeding sites. However, the study only looked at one wolf pack in one region over two years, so the results may not apply everywhere. The researchers were also limited by the number of horse remains they could recover and analyze.
What the Results Show
The most striking finding was how much of the wolf pack’s diet consisted of horses. In 2017, horses made up 85% of the biomass (total weight of food) that wolves consumed. In 2018, this increased to 93%. This is extremely high specialization on a single prey species. To put this in perspective, wolves typically eat a variety of prey animals, so having horses comprise nearly 90% of their diet shows very strong preference for horses.
The researchers found 19 feeding sites where wolves had eaten horses, and all of them contained horse remains. Importantly, 26% of these feeding sites were located within the wolf pack’s core territory—the area where they spend most of their time. This suggests that hunting horses wasn’t just occasional; it was a central part of their survival strategy.
When researchers looked at which horses were being killed, they found a mix of ages. Foals (baby horses less than one year old) made up 12% of predation events, juveniles (horses between 1-3 years old) made up 38%, and adult horses made up 50%. This shows that wolves were successfully hunting horses of all ages, not just the young and weak ones. The fact that they were killing so many juveniles is particularly important because it affects the future population of wild horses.
The genetic analysis revealed that the 39 horses identified from wolf feeding sites and droppings came from 10 different family groups out of 14 families that researchers could identify in the wild horse population. This means the wolves were hunting horses from most of the families in the area, not just targeting one particular group. The fact that researchers could trace family relationships through DNA showed that predation was affecting multiple horse lineages, which has implications for the genetic diversity of the wild horse population.
Previous research suggested that wolves only occasionally hunt horses when other prey is scarce. This study challenges that assumption by showing that wolves can specialize heavily on horses when they are available. The 85-93% figure is much higher than what most scientists expected. This aligns with recent research showing that predator diets are more flexible than once thought—when preferred prey becomes abundant, wolves will focus on it almost exclusively. However, most earlier studies didn’t have the genetic tools to identify individual prey animals, so this research provides much stronger evidence than was previously available.
This study followed only one wolf pack in one region of Portugal, so the results may not apply to other wolf populations or other parts of the world. The researchers could only analyze horses they recovered from feeding sites and wolf droppings, so they may have missed some predation events. The study lasted only two years, which is relatively short for understanding long-term predation patterns. Additionally, the researchers didn’t have complete information about how many horses were available in the area, so they couldn’t calculate exactly how much of the horse population was being killed each year. Finally, this study doesn’t tell us whether this level of predation is sustainable or whether it will eventually reduce the horse population significantly.
The Bottom Line
If you manage wild horse populations or live in areas with both wolves and horses, this research suggests you should monitor predation carefully and consider management strategies. These might include protecting foals during vulnerable seasons, maintaining adequate alternative prey for wolves, or using non-lethal deterrents. The confidence level is moderate to high for this specific region, but recommendations for other areas should be adapted based on local conditions. Consult with wildlife managers and conservation experts before implementing any changes.
This research matters most to: wildlife managers responsible for wolf or horse conservation; horse owners with animals in wolf territory; conservation organizations working in Europe; and policymakers deciding how to balance wolf and horse protection. It’s less relevant to people in regions without wild wolves or free-ranging horses, though the methods used here could apply to other predator-prey relationships.
Changes in predation patterns would likely take months to years to become apparent. If management strategies are implemented, it could take 2-3 years to see measurable changes in horse population trends. Long-term monitoring over 5-10 years would be needed to determine whether interventions are working.
Frequently Asked Questions
How much do wolves eat horses compared to other animals?
In this Portuguese study, horses made up 85-93% of wolf diet over two years, far exceeding typical predation patterns. This extreme specialization occurred because horses were abundant and alternative prey was scarce in the study area.
Can wolves successfully hunt adult horses or just young ones?
Wolves successfully hunted horses of all ages. Adult horses comprised 50% of predation events, juveniles 38%, and foals 12%, showing wolves can overcome even large prey when they specialize in hunting them.
How did scientists figure out which horses wolves were eating?
Researchers used DNA analysis of wolf droppings and remains found at feeding sites to identify individual horses. They compared this DNA to genetic samples from wild horses, allowing them to identify 39 specific horses that were killed.
Does this study mean wolves will always hunt horses this much?
This study shows what happened in one region with one wolf pack over two years. Predation patterns depend on how many horses and other prey animals are available, so results may differ in other areas or time periods.
What should horse owners do if wolves are in their area?
This research suggests monitoring predation carefully and considering protective measures like protecting foals during vulnerable seasons, maintaining alternative prey for wolves, or using non-lethal deterrents. Consult local wildlife managers for region-specific recommendations.
Want to Apply This Research?
- If you manage wild horses or wolves, track monthly predation events by recording the number of horse remains found at feeding sites, the age of killed horses, and GPS coordinates of predation locations. This creates a dataset similar to what researchers used in this study.
- Users managing wildlife could implement monthly patrols of known wolf feeding sites to document predation patterns, collect GPS coordinates of kills, and photograph remains for identification. This data feeds directly into conservation decision-making.
- Establish a long-term monitoring system that tracks predation events quarterly, maintains a database of individual horses killed (using photos and descriptions), and maps feeding site locations. Compare trends year-over-year to detect changes in wolf hunting behavior or horse population impacts.
This research describes predation patterns in one specific region of Portugal and may not apply to other areas or wolf populations. The findings are based on one wolf pack studied over two years. Before implementing any wildlife management strategies based on this research, consult with local wildlife biologists, conservation experts, and relevant government agencies. This article is for informational purposes and should not replace professional wildlife management advice. If you own horses in wolf territory, work with local wildlife authorities to develop appropriate protection strategies for your specific situation.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.