In former times, Hog deer were abundant and widely distributed throughout their range. Currently, this endangered species has lost a considerable part of its original range and population. The remaining isolated populations now inhabit south and south-eastern Asia. The animal is so called due to its habit of holding its head low in hog-like manner, when running through vegetation. Hog deer have typical appearance for species of the genus Axis. However, they differ from other Axis deer by low and sturdy build as well as short face and steep profile.
Hog deer are found from Pakistan and northern India through Nepal and Bhutan to mainland south-eastern Asia, Burma, Thailand as well as in Sri Lanka, Australia and the U.S., where they have been introduced. Preferred habitat of this species is tall grassland. They also favor reed beds on floodplains, adjecent to big rivers. Hog deer live in open areas and avoid closed forests. They may occasionally be seen in agricultural areas and scrubland.
Hog deer are solitary animals. However, they may occasionally be observed feeding in small herds in open terrains with an abundance of food. They are also known to form small family units. Periods of increased activity are dawn and dusk, rarely, the daytime hours. In areas with excessive hunting, Hog deer have to lead nocturnal life. These mammals are generally sedentary. They tend to live in the same area and do not migrate. Males of this species display highly territorial behavior, marking their home ranges with a special substance, produced by their scent glands. When facing a threat, members of a group typically flee in various directions. They hide in dense vegetation until the danger has passed. When running, these animals hold their heads low and their tails raised, exposing the white colored under-side. They commonly use alarm calls such as sharp barks and whistles.
Hog deer have a polygynous mating system, where each male mates with a number of females. However, some males of this species exhibit monogamous behavior, mating and defending only one female. Populations within the natural range mate in August-October, while introduced populations may have different timing of reproduction. During this period, male hog deer engage in harsh competition, aggressively defending their mating rights. Females yield a single, fully-developed fawn in May-July, after 8 months of gestation. The fawn is typically born in a secluded place, among dense grass or reed beds, where it's protected from numerous predators of the area. During the first several days of its life, the baby lives alone while the mother feeds. She occasionally visits the fawn to suckle the baby. The young deer is weaned at 6 months old. The age of reproductive maturity is 8 - 12 months old.
During the last few decades, Hog deer have suffered from sharp population decline. Currently, these animals live in small, isolated populations in the remaining fragments of their former range. They continue to face some serious threats such as hunting for food. They are still losing their habitat because of human settlements and agricultural development. As a result, many populations become isolated in small patches of favorable habitat.
The IUCN Red List and other sources don’t provide the number of the Hog deer’s total population. However, according to the IUCN Red List resource, specific populations have been estimated in some areas. For example, in India there are: 10,000 deer in Kaziranga; 1,500 deer in Manas; 500 deer in RG Orang (all in Assam); more than 250 deer in Jaldapara; and 100 deer in Keibul Lamjao (in Manipur). In addition, the population in Royal Manas National Park of Bhutan is likely to be more than 150 deer. Overall, Hog deer’s numbers today are decreasing today and the animals are classified as Endangered (EN) on the IUCN Red List.
Due to their diet Hog deer’s are assisting in seed dispersal.