A study led by researchers at the University of Hawaiʻi at Mānoa’s College of Tropical Agriculture and Human Resilience (CTAHR) has revealed that wild ungulates—hoofed animals like axis deer, goats, and others—are significantly reducing forage availability on working cattle ranches in Hawaiʻi. The research, published in the journal Rangeland Ecology & Management, surveyed 35 sites and found that 66% of them experienced measurable forage loss due to these animals. Axis deer were identified as the main cause of forage decline on Hawaiʻi Island and Maui, where they are especially prevalent. Non-native ungulates were introduced to Hawaiʻi between the 1700s and 1960s, often for hunting or agriculture, but they have since become invasive species. On Maui, axis deer were found at 95% of the surveyed sites, with an estimated population of 47,000 deer spread across about a third of the island, reaching elevations as high as 2,150 meters (7,050 feet). To measure the impact of these animals on vegetation, researchers used motion-triggered trail cameras and compared them with fenced plots that excluded ungulates. Sites where axis deer were present had about 24% less forage growth than those without them. Feral goats had similar effects, while wild pigs and mouflon sheep were more commonly found at higher elevations, where forage grows faster, complicating land management strategies. Some of the study sites were located in areas affected by the August 2023 wildfires. Researchers warned that overgrazed lands recover more slowly after fires and are more prone to invasive weeds like fireweed, which were found at nearly 70% of the sites. This combination of grazing pressure and fire damage could further degrade rangeland health and hinder recovery efforts. Greg Friel, a Maui cattle rancher and co-author of the study, noted that ranching families have long recognized the impact of deer on forage availability. However, this research provides a more detailed understanding of the extent of the problem and the complex interactions between different species and environmental factors. The findings could help inform more effective land management practices to protect both livestock and native ecosystems.