Facial vibrissae on the maned sloth are sparse. The maned wolf is a solitary animal. Increased testosterone may be the cause of maned lionesses reported in northern Botswana. Interestingly, the maned wolf is poorly parasitized by fleas. Often, maned wolves defecate on the nests of leafcutter ants. The maned wolf is not closely related to any other living canid. The preferred habitat of the maned wolf includes grasslands, scrub prairies, and forests. Melanistic maned wolves do exist, but are rare. It is the second-largest native canid on the continent, after the maned wolf. The maned wolf participates in symbiotic relationships. Until 1996 the maned wolf was a vulnerable species by the IUCN. Gauchos called Fuegian dogs "maned dogs" because of their resemblance to the maned wolf. The situation of the maned wolf in Bolivia and Paraguay is uncertain. The maned wolf is particularly susceptible to potentially fatal infection by the giant kidney worm. Although the maned wolf displays many fox-like characteristics, it is not closely related to foxes.