In Alaska, it is illegal to shoot a wolf with a rimfire rifle because wolves are classified as big game. The state predator control program includes aerial shooting. In 2007 state biologists' goal was to have volunteer hunters kill 407 to 680 wolves by the time the predator-control season ended April 30, but high fuel prices and poor flying conditions kept hunters from meeting that goal. A subsidy of $150 per wolf offered by the Alaska Department of Fish and Game was overturned by a judge on the grounds that only the Board of Game had the power to offer bounties. Despite relatively heavy hunting and trapping over the last century in Alaska, wolves occur on nearly all of their traditional habitat throughout mainland Alaska. Alaska currently has five wolf control programs that comprise about 9.4% of the state's land area. A closely controlled permit system is used in allowing aerial or airborne methods to remove wolves in designated areas. Wolf numbers are temporarily reduced in these areas, but are not permanently eliminated from any area. Wolf populations in North America commonly sustain annual harvests or natural mortality rates of 20–40% without experiencing a year-to-year decline in numbers. Sarah Palin of Alaska in 2007 approved the use of this provision in the law to shoot wolves and bears while flying for the purpose of protection of property.