The mammals of Jeju Island are distributed among 5 orders and 114 families and 5 species . Thus, the distribution of mammals in Jeju Island is very poor in species and numbers because Jeju island is isolated from the Korean peninsula long ago. Their population has been reduced due to the decrease in food because of the use of rodenticides and pesticides in recent years and indiscreet fishing. Weasels, badgers, and gazelles are inhabited in Hallasan. The number of weasels and badgers are significantly reducing. Boar and Formosan deer is already extinct. Roe deer, the largest mammal in Hallasan, was once in danger of extinction. But now its population increased due to protection policies and a lot of efforts by people in Jeju island.