Now is the birthing migration season for Tibetan antelope. Thousands of Tibetan antelopes head north in the Changtang National Nature Reserve to their "large delivery room" set amongst snow-capped mountains. But research has found that some Tibetan antelopes now choose to remain where they are for labor.

The Changtang National Nature Reserve is located in the northern part of the Tibet Autonomous Region and is the world's second largest nature reserve, with a total area of 298,000 square kilometres. At present nearly 200,000 Tibetan antelopes live in the reserve, mainly in three areas: Amdo County, Nyima County, and Shuanghu County of Nagqu Prefecture.

"From mid-May to June each year, a large number of Tibetan antelopes migrate about 200-400 km to a fixed area for giving birth, before returning with their new babies to their original habitats, but there are also some exceptions to this," said Sherab, the Director of Nagqu Prefecture's Forest Public Security Bureau. According to observations, in Xainza and Nyima Counties each there are more than 20,000, and in Serling Tso Lake area there are more than 3,000 Tibetan antelopes that have chosen to breed locally and not migrate with the herd.

Pontod, Deputy of Shuanghu County's Forestry Bureau said that on the basis of many years' observation near Barling Township, more than 2,000 Tibetan antelopes there also stayed in the same location for birthing season.

According to reports, these antelopes not only do not migrate for the birthing season, but every year in late October to mid-November during mating season and the long feeding season they also won't leave their fixed habitats. The existence of this special group breaks the singular cognitive habit of migration in Tibetan antelopes.

Academic circles currently have no authoritative or unified explanation regarding these conflicts of migration during birthing season within Tibetan antelope populations. Similarly, academics are also unable to agree on the reasons for non-migration of Tibetan antelopes, but Pontod speculates that they may be related to improvements in the ecological environment, grasslands restoration, and sufficient food sources.

The Tibetan antelope is a kind of animal under state protection that lives mainly in the alpine desert areas of Tibet, Qinghai and western Xinjiang. Eighty percent of the antelopes' territory is in the Changtang National Nature Reserve of Tibet Autonomous Region.

Since the end of last century, the Chinese government has established a number of nature reserves in Tibetan antelope distribution zones, and these areas have also set up forest public security bureau stations to effectively curb illegal poaching of Tibetan antelopes.