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Aerial assessment shows deer overpopulation on Molokai

A herd of deer that from the air looks like a colony of fast-moving ants spreads out across a pasture on Molokai during an aerial assessment in December. Photos courtesy of DLNR

The Maui News

A recent aerial assessment of Molokai illustrated just how overpopulated the island is with axis deer, which continue to trample plants, spread invasive weeds and devour vegetation that leaves the island susceptible to runoff.

On Maui and Molokai, nonnative axis deer continue to devastate private agricultural land and are pushing higher and higher into forested lands, according to the state Department of Land and Natural Resources. At lower elevations their voracious appetites and extreme herd sizes are leaving some areas looking like moonscapes.

“Cattle ranchers have been the hardest hit,” James Espaniola, a forestry and wildlife technician with the DLNR Division of Forestry and Wildlife, explained during a recent helicopter flight over the island. “They do their part in rotating the use of pasture lands to prevent overgrazing by moving their cows around. Unfortunately, the deer remain, and they devour any living vegetation, which doesn’t allow for plant regeneration.”

Within the nonnative forest around the airport on Molokai, every single tree is devoid of greenery. In heavy rain events, the lack of groundcover and healthy trees to slow rain penetration into the ground has created excessive runoff, which makes its way down to the ocean and onto nearshore reefs. After a big rain last month, waters along the south shore of Molokai were chocolate brown, hundreds of feet seaward, DLNR said in a news release Thursday.

Deer are spotted on Molokai during an aerial assessment in December. The overpopulated animals pose threats to farms and native ecosystems across Maui Nui.

The overpopulation of axis deer has the greatest impact on agricultural lands, some of which are adjacent to state forest lands. DLNR Chairperson Suzanne Case said that the deer are spreading further into deep valleys and remote ridges, where they trample and eat plants and spread invasive weeds.

“We need to protect our native forests because they capture rain and cloud moisture, replenishing freshwater streams and underground water sources,” Case said. “When hooved animals, all of which are not native to Hawaii but were introduced by foreigners, turn these ancient forests into bare ground, the steep mountainsides rapidly erode which deposit mud on beaches and coral reefs.”

One of the most effective ways to keep axis deer out of forests is fencing, DLNR said. While the fencing in place across 111,000 acres of Maui Nui continues to be mostly effective, many were built decades ago and are only 4 feet high, built originally to keep pigs and goats out. Axis deer can easily jump these fences and are increasingly gaining access to those areas, so now DLNR and its partners are retrofitting existing fences to be 8 feet high.

DOFAW Maui Branch Manager Scott Fretz said that DLNR and DOFAW are working to combat the axis deer issue by:

• Participating in the Maui Axis Deer Task Force. DOFAW staff are also working to improve control through population-based spatial planning and increasing opportunities for deer harvest.

• Using additional funding for deer control from state and county sources for fencing, harvest and watershed protection.

• Looking at expanding on the success of wildlife control permits and other hunting efforts, which result in more than 7,000 axis deer being harvested on Maui annually.

• Working to establish additional public hunting agreements with private landowners.

• Continuing to maintain and build fencing and control deer on significant watershed lands that are vital for clean water, natural resource protection, endangered species, agriculture and the economy.

Hunters currently have no limits on how many axis deer they can take, and DOFAW is encouraging hunters not only to focus on bagging trophy bucks, but to help cull doe out of the large herds. A recent study that modeled axis deer populations in Hawaii and was published in University Press’ “Pacific Science” journal found that “on Maui, the axis deer populations are female-biased, comprising as much as 70 percent individuals … Effectively reducing axis deer will most likely require an annual removal of approximately 20-30 percent of the population with a greater proportion of females to increase population decline.”

“In order to get to that manageable population size it’s going to involve the state and entire communities,” Espaniola said. “A lot of people are working on this problem, and we are beginning to see better progress.”

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