Sexing badgers is not an easy task because there is remarkably little sexual dimorphism in this species. In other words, the males and females look very similar. During the breeding season, sexing can often be done on the bases of descended testes, lactation (i.e. highly visible teats) or, sometimes, cub association. More generically, it is sometimes possible to separate males and females based on stature. Males tend to be bigger than the females, with a broader head, fuller cheeks and a less tufted tail. I have seen many badger watchers state with apparent confidence the sex of a badger based on these morphometrics, although I know several badger biologists that dispute this as a reliable method of sexing.
Studies on the variation in skull morphology by Russian Academy of Science biologists have revealed that some craniological characteristics show dimorphism between the sexes. Variation was found in the overall skull size, the length of the lower mandible (jaw) and in the molars, but the most stable characteristic was the length (and to a lesser extent, the width) of the upper canines, which are significantly larger in males than females. Given the spread of their data, however, questions remain as to whether canine size is a fool-proof method of sexing a badger. Cranial measurements taken together might be more reliable, although work by the WildCRU team at Oxford University on the badgers in Wytham Woods has found that the average variation in skull size between the sexes can be of the order of half a millimetre. Such measurements can only be accurately obtained from a dead animal. According to the Devon Badger Group, the only way to be sure is to roll it over!
Males are referred to as boars, while females are called sows.