In 1870, Java’s governor sent 12 rusa deer to New Caledonia as a gift; they multiplied into an estimated 250,000 to 370,000 invasive animals

In 1870, 12 rusa deer were brought to New Caledonia as a diplomatic gift from Java, where they quickly multiplied into an estimated 250,000 to 370,000 animals. These deer descended from the original 12 founders and inhabited nearly every land habitat on Grande Terre, the main island of New Caledonia. Native plants in New Caledonia had not evolved with grazing animals, leading to a dramatic expansion of the deer population over time.

The deer's presence poses a significant threat to the environment, as they overgraze plants and cause soil erosion. Their diet consists of various plants, including 25 grasses, 15 forbs, 26 trees and shrubs, and 12 vines and ferns, with nearly half of their preferred food plants being alien species. While hunting efforts have been made, the deer's ability to migrate freely across the landscape and their high reproductive rate make control efforts challenging and costly.