The American badger is primarily nocturnal, generally foraging at night and remaining underground during daylight hours (1) (3) (6). As an adaptation to its partially fossorial lifestyle, the American badger has a third eyelid, known as a ‘nictitating membrane’, which protects the eye from soil (4) (7). Its eyesight is poor, although its hearing and sense of smell are acute (7).
The burrow systems of this species are used for dens, feeding and as a means of escape (8), and the American badger either excavates a burrow itself or modifies one formed by another animal. These burrows can be up to ten metres long and three metres deep (6), and usually have a single entrance, which is partially covered in soil. The shallow non-breeding burrows of this species are around 30 centimetres in diameter, with burrows used during the breeding season being much larger and deeper (4). An expert digger, the American badger has powerful legs which enable it to dig with remarkable speed, allowing it to disappear from sight rapidly (8).
The home range of the American badger, which usually varies in size between 2 and 725 hectares (1), can become much larger while the male tries to locate receptive females in the area (2) (7). Neither sex is territorial and many home ranges are known to overlap (2) (7). A typically solitary species, the American badger only comes together as breeding pairs, family groups and as siblings (3). The American badger has well developed scent glands (7), which may be used for defence (8), or to attract a mate during the breeding season (4).
The American badger is a polygamous species and mates in summer and early autumn (5) (6). This is followed by a period of delayed implantation, which pauses development of the embryos until February (6) (8). The total gestation period is around seven months, although actual embryo development only occurs for around six weeks (6).
The female American badger gives birth to a litter of between one and five blind, lightly furred young between March and April (3) (5) (6) (8), in an underground nest filled with grass (5) (6). The young begin to open their eyes after four weeks and are fully weaned after six to eight weeks (5) (6). During this period, the young rarely go above ground, except when the female changes dens, when she will usually carry the young (3). The young remain with the female until the autumn, after which they disperse (5).
The American badger does not hibernate, instead reducing above-ground activity by entering a state of torpor in times of bad weather, and surviving on fat reserves when prey is scarce (2) (8). If prey is limited, pregnant females must sustain themselves and the growing foetuses on stored fat. Due to this, American badger young are much smaller in relation to the female’s body size than most other mammals (2).
An opportunistic feeder, the American badger has a highly variable diet, consisting mainly of small rodents, such as ground squirrels, voles, mice, pocket gophers, rabbits, marmots and prairie dogs (1) (2) (6) (7) (8). Birds and their eggs, as well as reptiles, amphibians and insects, are also taken (1) (6) (8). Most rodent prey is acquired by unearthing burrows, and is occasionally buried and saved (6). American badgers have been known to join up with coyotes (Canis latrans) and hunt together (2) (8).