Tigers use 4 senses to communicate i.e. sight, smell, hearing and touch
A tiger shows its aggression by lashing its tail violently from side to side. It keeps its head low and gets up on its hind legs, twists its ears to show the ear spots and opens its eyes wide to make eye contact. During this time, its lips are closed in the form of a straight line.
When tigers are nervous, they incline their head and snarl or they roll over with a defensive roar. If a tiger feels threatened, it will retaliate by getting up on its hind legs in a "south paw" like stance like a boxer asking one to come on. During this time its ears are laid back, its teeth are bared, the nose is wrinkled and, the eyes are narrowed to slits and the tail is held low.
When greeting another tiger, they respond by rubbing their body against each other. Two tigresses may get friendly but a tiger won't stand the presence of another tiger in its territory unless it is its sibling. While investigating the surroundings, a tiger's ears are upright and alert, and the tail is held high.
Smell and Touch
The first sign of a tiger maturing is when it begins to mark its territory. It does this by spraying a mixture of urine and scent and leaving scratch marks on barks of trees. There are scent glands between the tiger's toes which produce secretions while the tiger scratches the barks of trees. A tigress increases her scent markings a few days before her estrus to attract a mate. The tiger will respond by increasing his scent markings around the female's territory.
If a tigress is interested in getting friendly, she will roll on the place where the other tiger has rolled and if she is interested in mating, she will roll on the place where the other tiger has urinated and will then urinate on the same spot herself.
Tigers communicate by exchanging scents while rubbing their faces and cheeks on each other. This reinforces the social bonds between a mother tigress and her cubs, and between courting pairs.
The base of the tail also has a scent gland which may be rubbed against objects or familiar tigers.
Flehmen is another behavior noticed in the tigers. When a tiger breathes in an unfamiliar smell or a smell that it does not like, it wrinkles its nose while drawing its lips and it opens its mouth slightly to stick out its tongue and reveal its canines.
When tigers call each other, they make a special ah-ah-ah sound.
Loud roars (which can be heard over 4 kilometers away), are used as a signal 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 made by releasing air through closed lips. It is 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.
Grunting, meowing, purring, and woofing are some other noises that tigers make when they are in close contact.
Why does a Tiger attack?
It is a myth that tigers are blood thirsty creatures. When a tiger attacks, it attacks with a purpose. An attack is usually driven by hunger or expediency for example a tigress will attack if it senses that its cubs are in danger. Tigers seldom attack human beings and avoid human beings as far possible because it fears the unknown and human beings are not its natural prey. But if roused, a tiger is a powerful killer with natural weapons that no man can endure. The tiger has razor sharp senses and is almost never taken unawares. But in the rare circumstances that it is caught unawares, its first thought is to escape and if there is no route to escape, it attacks.