their tactile vibrissae, in the form of whiskers, on their chin and upper lip, aid their eyesight in the dark of the cavities. although they are mammals, they struggle to regulate their body temperature. despite their thick fur they rely on lazing in the sun to heat themselves up. they usually become active after sunrise when they will move into the sun to warm up before going off to feed. they have to control their body temperature in the converse too; a few hours in the sun puts them in very real danger of heat stress and possible mortality, which is why cavities are a survival prerequisite. they can also counter overheating by stretching out with the hind feet upturned to expose their moist foot--pads. at night and on cold days they tend to stay huddled in their hideaway. they can also be seen ""stacking"", where they lie on top of one another, in layers, for warmth. they have a glandular patch on the back so this stacking is also useful for transmission of scent and imprinting.