The golden eagle (Aquila chrysaetos) is one of the best-known birds of prey in the Northern Hemisphere. It is the most widely distributed species of eagle. Like all eagles, it belongs to the family Accipitridae. These birds are dark brown, with lighter golden-brown plumage on their napes. Immature eagles of this species typically have white on the tail and often have white markings on the wings. Golden eagles use their agility and speed combined with powerful feet and massive, sharp talons to snatch up a variety of prey, mainly hares, rabbits, marmots and other ground squirrels. Golden eagles maintain home ranges or territories that may be as large as 200 km2 (77 sq mi). They build large nests in cliffs and other high places to which they may return for several breeding years. Most breeding activities take place in the spring; they are monogamous and may remain together for several years or possibly for life. Females lay up to four eggs, and then incubate them for six weeks. Typically, one or two young survive to fledge in about three months. These juvenile golden eagles usually attain full independence in the fall, after which they wander widely until establishing a territory for themselves in four to five years. The golden eagle is a very large raptor, 66 to 102 centimetres (26 to 40 in) in length. Its wings are broad and the wingspan is 1.8 to 2.34 metres (5 ft 11 in to 7 ft 8 in). Golden eagles' wingspan is the fifth largest among living eagle species. Females are larger than males, with a bigger difference in larger subspecies. Females of the large Himalayan golden eagles are about 37% heavier than males and have nearly 9% longer wings, whereas in the smaller Japanese golden eagles, females are only 26% heavier with around 6% longer wings. In the largest subspecies (A. c. daphanea), males and females weigh typically 4.05 kilograms (8.9 lb) and 6.35 kg (14.0 lb), respectively. In the smallest subspecies, A. c. japonica, males weigh 2.5 kg (5.5 lb) and females 3.25 kg (7.2 lb). In the species overall, males average around 3.6 kg (7.9 lb) and females around 5.1 kg (11 lb). The maximum size of golden eagles debated. Large subspecies are the heaviest representatives of the Aquila genus and this species is on average the seventh-heaviest living eagle species.  Golden eagles are fairly adaptable in habitat but often reside in areas with a few shared ecological characteristics. They are best suited to hunting in open or semi-open areas and search them out year-around. Native vegetation seems to be attractive to them and they typically avoid developed areas of any type from urban to agricultural as well as heavily forested regions. In desolate areas (e.g., the southern Yukon), they can occur regularly at roadkills and garbage dumps. The largest numbers of golden eagles are found in mountainous regions today, with many eagles doing a majority of their hunting and nesting on rock formations. However, they are not solely tied to high elevations and can breed in lowlands if the local habitats are suitable. Below are more detailed description of habitats occupied by golden eagles in both continents where they occur. Golden eagles usually hunt during daylight hours, but were recorded hunting from one hour before sunrise to one hour after sunset during the breeding season in southwestern Idaho. The hunting success rate of golden eagles was calculated in Idaho, showing that, out of 115 hunting attempts, 20% were successful in procuring prey. A fully-grown golden eagle requires about 230 to 250 g (8.1 to 8.8 oz) of food per day but in the life of most eagles there are cycles of feast and famine, and eagles have been known to go without food for up to a week and then gorge on up to 900 g (2.0 lb) at one sitting. Scarce resident in high mountainous areas, from Northern Baluchistan up to Northern Borders of Pakistan. A Few Sub Adults migrate to foothills in Winter.