Invasive species like the axis deer take a toll on Hawaiʻi’s environment and threaten the operations – and futures– of local farms and ranches across the islands.
A new study from the University of Hawaiʻi quantifies how invasive hooved animals like deer, sheep, goats and pigs devour and damage foraging grasses on ranchland on Hawaiʻi Island and Maui.
Melissa Price is a professor and researcher with the UH College of Tropical Agriculture and Human Resilience, or CTAHR, who contributed to the study.
She spoke with HPR to explain the results they gathered and what they could mean for Hawaiʻi's farms moving forward.
Interview Highlights
On the results of the study
MELISSA PRICE: It was really clear that axis deer are hammering away at the forage, and this is something that the ranchers — this is why they asked for this study to be done. Essentially, ranchers were like, "Look, we're getting put out of business by these access deer.” So, 66% of sites showed forage loss. 95% of the sites that had the potential to have axis deer, had them show up on the cameras, so they're definitely present. They're causing a huge amount of these losses.
On improving axis deer management methods
PRICE: Basically, the only thing you can do is build a fence that's eight foot high, which is really expensive to build, and then just hammer away at them. They twin — they produce two fawns at a time, their reproductive rate is really high — and there's nothing to kill them other than cars and people, basically, right? So, without a really intensive, targeted effort at removal, their numbers have just skyrocketed. … If you have targeted removal of females of does, you can remove a lot less animals overall and achieve the same lower levels of populations compared to if you have hunters who are largely maybe doing trophy hunting.
On the importance of the study
PRICE: I think the study really highlights the importance of engaging communities and private landowners and DLNR and other folks who are managing lands and species; really finding collaborative solutions where they can work together to solve problems. The animals moving across the landscape don't see boundaries. They don't know if it's DLNR land or ranch land or agricultural land. They're just trying to move where there's food or where there's shelter or comfortable space for them, and so solving these problems really takes all of us working together to find collaborative problems that help us achieve food goals, sustainable food goals, but also sustainable ecosystems.
More information about the research can be found here.
This story aired on The Conversation on Sept. 29, 2026. The Conversation airs weekdays at 11 a.m. Jinwook Lee adapted this story for the web
