X. Communication:

Smell and Touch: Tigers have a well-developed sense of smell; however, it's rarely used for hunting. Smell is most commonly used to communicate with other tigers. When smelling another tiger's scent mark, a tiger will wrinkle its nose and hang out its tongue in a grimace called flehmen. Flehmen is used to draw a scent to the Jacobson's organ (a sensitive organ in the roof of the mouth), which receives the chemical information. Through scent marking, tigers can communicate their home range boundaries, and female tigers can advertise their readiness to mate. A tiger can tell whether a scent belongs to a local resident or a stranger, a male or a female. Overall urine is the most common scent communicator. Tigers use urine (marking fluid) most often to mark home range boundaries. A female tiger increases her rate of scent-marking a few days before (not during) estrus to attract a mate. The resident male usually responds by increasing his scent marking around the female's territory while she's in estrus. Tigers and cats in general, communicate by exchanging scents through body contact. Tigers typically greet by rubbing their faces and cheeks on each other. By rubbing, body scents from the face glands are transferred between cats, which reinforce social bonds. Face rubbing can be seen between mother tigers and their young, and between courting pairs. The base of the tail also has a scent gland which may be rubbed against objects or familiar tigers. Glands between the toes may produce secretions which are left when tigers use scratching posts. Anal glands produce a secretion, that when mixed with feces, produces a potent-smelling home range marker.
Tigers also have a well-developed sense of touch. They have tactile sensory hairs called whiskers on their cheeks, above the eyes, and on the muzzle. The whiskers, especially those on the muzzle, are used to feel for objects in the environment. Mother tigers and cubs, and courting pairs often rub against and lick each other.

Visual: Tigers also have good vision, both during the day and at night. During the day, a tiger's sight is about the same as a human's, though its visual acuity (ability to see detail) is not as good. At night, when a tiger usually hunts, its sight is six times better than a human's. A tiger sees better at night compared to a human because its eye has a larger anterior chamber and lens, and a wider pupil. Like other cats, the tiger's retinas have mostly rod receptor cells which are sensitive to low light levels and movement. Tigers and cats in general have a cluster of cone receptor cells in each retina indicating they have some color vision. However, scientists believe a cat's cone cells are used primarily to enhance day vision, not for color vision. Tigers also have a layered structure at the back of the eye behind the retina called the tapetum lucidum. This mirror like structure reflects light (that hasn't already been absorbed by the eye) back into the eye a second time to help produce a brighter image. The tapetum lucidum is what causes the eyes of cats to shine when a light is shown directly at them. Tigers have highly developed binocular vision, similar to that of humans. Binocular vision enables tigers to judge distances when jumping or stalking. Tigers have broadly elliptical pupils which appear round when dilated at night, but elliptical during the day. The pupils of smaller cats close to vertical slits in daylight.
A tiger's body language is similar to that of other cats. For instance, when a tiger shows aggression (an offensive threat) the tail is usually lashed from side to side, the head is held low, the ears are twisted so that the backs face forward (showing the ear spots), the eyes are opened wide, and the mouth is almost closed with the lips forming a straight line. During a defensive threat, the ears are normally laid back, the teeth are bared, the nose is wrinkled, the eyes are narrowed to slits, and the tail is held low. When greeting another tiger or investigating surroundings, a tiger's ears are upright and alert and the tail is held high.

Vocal: Tigers roar to advertise their location. Roars are used for long-range communication and can be heard for over 3 km (2 mi.). Roars can be used as a warning to keep other tigers away or as an invitation to bring another tiger closer. Loud moans are most often heard in combination with roars. Soft moans are used by mother tigers to gather cubs, or by individuals to announce their approach to other tigers. Prusten is a short, noisy, low-intensity sound used as a friendly greeting or a reassuring call between a mother tiger and her cubs, or a courting pair. Growls, snarls, and hisses are used in aggressive and defensive encounters. Other close contact vocalizations include grunting, meowing, purring, and woofing.

Hearing: Tigers have exceptional hearing, which they use to locate prey in dense cover. Their hearing is probably similar to the hearing of domestic cats. Domestic cats can hear sounds in the range of about .2 kHz to 65 kHz. The average hearing range for humans is about .02 kHz to 20 kHz.