The tiger is the world's largest cat species with wild populations occurring from the Far East of Russia to the rainforests of Indonesia. Tigers are largely solitary and territorial; they represent the top of the food chain in all areas where they occur.

Subspecies and Populations

Wild tigers have historically been grouped into subspecies, (Thailand's tigers are typically classified as (Panthera tigris corbetii)). Recent genetic analysis has reviewed subspecies status and discovered a new subspecies , Panthera tigris jacksonii, that occurs in southern Thailand and mainland Malaysia. Prior to this new research there was some question about the validity of subspecies. Sometimes subspecies named decades ago before the advent of modern genetic analysis appeared to by somewhat arbitrary, However, recent work has related the time of divergence of different subspecies to specific geological events such as sea level changes and volcanic eruptions (Luo et al. 2005).

From a conservation perspective the primary genetic and demographic issues are not the subspecies status but rather the size and degree of connectivity of individual populations. If populations are small and isolated, they are more likely to go extinct. The current conservation paradigm, especially for large carnivores and other area sensitive species, is to manage at the level of landscapes, which are composed of protected area complexes linked by forests where human activities dominate. An important but simple idea is that a set of nearby populations are linked via dispersal corridors to form a metapopulation (a set of loosely connected populations).

Physical Characteristics

Data from recent field studies of wild caught animals suggest there is variation in body size between populations. For example, the largest male tigers in Nepal weigh in excess of 250 kg and measure over 3.20 m long (Smith 1984); tigers in Thailand are probably much less massive. According to the eminent Thai naturalist, Dr. Boonsong Lekagul, the largest tiger ever accurately measured in Thailand was 2.82 m between pegs (from nose to tail in a straight line).  Its weight was not recorded.

Habitat

For tigers to survive successfully in the wild, they must have sufficient water, cover and abundant large mammal prey weighing between 50 and 100 kg. On average, tigers make 40 to 50 kills a year when there is sufficient large prey available (Chunderwat et al. 1999; Seidensticker & McDougal 1993; Sunquist 1981). In Thailand, prime prey includes sambar deer, gaur, banteng, barking deer, and wild pig. Achara Simchareon’s study of tiger diet in Huai Kha Khaeng  found that the dominant prey species is banteng. Opportunistically, tigers also attack and eat bears, tapir, young elephants, primates, porcupine, and even peafowl (Petdee 2000; Prayurasiddhi 1997).

Unlike in South Asia, where frequent encounters between humans and tigers have resulted in many instances of man-eating, Thailand has few records of man-eaters. Isolated cases have occurred in the past, with the most recent record in Khao YaiNational Park in 1976. After it was shot, the tiger was found to be old, with damaged teeth and other debilitating wounds rendering it incapable of killing its normal prey. Tigers in Thailand usually avoid human contact and livestock depredation is rare because domestic animals are less dependent on forest grazing than in South Asia.

Scent Marking

If tigers are present in an area, they leave overt evidence: sprayed scent marks, scrapes, scats and pugmarks (tracks) on trails, stream beds, and ridge tops, and claw marks on trees. Tigers spray urine on trees and shrubs or scrape and deposit urine on the ground to delineate their territories (see below). These scent marks leave an unmistakable pleasant odor (similar to buttered popcorn) that may last for several days. When fresh, it is detectable by humans up to 2-3 m  away (Smith et al. 1989).

Vocalizations

Of the many sounds a tiger is capable of emitting, the most likely to be heard is the awesome moaning, 'aa-oo-mh, aa-oo-mh', used during the mating season. This call carries over considerable distance, attracting the resident male to the estrous female. Other vocalizations, which may be heard at close range, include low growling, snarling and coughing grunts. The angry roar of a tiger is unforgettably terrifying.

Mating Behavior and Early Development

When tigers mate, they usually remain together from 2 to 3 days, copulating every 15 to 20 minutes day and night. After 102 to 105 days, the female dens in dense vegetation and produces on average 3 cubs. During the first 2-3 days after birth, the female remains at the den for up to 23 hours a day; she gradually leaves for longer periods until the den is abandoned when the cubs are about 2 months old. For the next 2-3 months, the female moves the cubs from place to place, but they still remain hidden most of the day.

Until the cubs are several months old the cubs go to a kill only after it has been made (Smith 1993).  By 6-7 months of age the cubs begin to accompany their mother on hunts but the final stalk and kill is by the mother alone. At 11-13 months the milk canines begin to protrude, pushed out be erupting adult canines that are fully erupted at 16-17 months. Even though they have the “equipment” to kill prey, young tigers require 2 to 3 additional months to learn to kill efficiently on their own. They gradually become independent from their mother but continue to hunt within the security of her territory.

From 19 to 24 months after her previous litter, a female may give birth to her next litter. Two months later, when she and the cubs abandon the den site, aggression between the female and her previous litter marks the onset of dispersal. The young leave the territory where they were born and raised and face the most critical period in their lives over the next few months of early independence. Approximately 40% of young males die during the dispersal periods (Smith 1993).

Territoriality and Homerange

Tigers are territorial. Females defend a territory from others of the same sex; males, which have territories overlapping those of 2-7 females, defend their territory to prevent intrusions of other males. Dispersing young face a gauntlet of resident animals guarding their territories and are often forced to reside temporarily in suboptimal habitat at the edge of protected areas where they may come into conflict with humans and their livestock. For females, the dispersal stage usually lasts about 1 year. About 45% of daughters settle next to their mother, who will often shift her territory slightly to accommodate a daughter. However, by the time the daughter is fully established as a resident, there is little overlap with her mother’s territory. For males the task of establishing a breeding territory is more arduous and dangerous. It may take more than 2 years and involve a series of aggressive encounters with resident males that can lead to serious, even incapacitating wounds and sometimes even death.