Hawaii officials believe they have successfully removed an invasive deer species from the southern region of Big Island with no confirmed sightings of axis deer in five years.

A U.S. Fish and Wildlife investigation determined that axis deer were introduced to Kau eight years ago by a Mountain View man, a rancher and a pilot from Maui who ran a sheep-for-deer swap across the islands in the late 2009, the Hawaii Tribune-Herald reported. The men told officials they wanted to see another hunting resource on the island. They were convicted for possessing game animals without a permit.

The deer cause millions of dollars’ worth of damage to crops and landscapes, according to the Big Island Invasive Species Committee. Because they can jump over 6 feet (2 meters), fences did little to stop them.

“It would have been the undoing of decades and millions of dollars’ worth of work,” said Committee spokeswoman Franny Brewer, if they remained unchecked

Multiple agencies such as the U.S. Geographic Survey, Three Mountain Alliance Watershed Partnership, the Nature Conservancy and the Hawaii Volcanoes National Park worked to eradicate the deer. Residents also aided the effort by reporting possible sightings, said Franny Brewer.

The last axis deer was killed in 2012, she said.

Officials set up game cameras across 8 square miles (21 sq. kilometers) and reviewed almost 7,000 hours to confirm that the deer were no longer present.

“With any invasive species, timing is key,” she said. “The fact that people reported it and said, ‘Hey, there is something going on here in Kau’” helped make the eradication effort a success.