On Wednesday, the first litter of Mexican gray wolf cubs was uncovered by officials at Mexico City's Chapultepec zoo.

The birth of the endangered animals is explained as a "worldwide success" by Zoo officials. The cubs are the first of their subspecies to be born through artificial insemination in Mexico. It is part of the effort by officials to reintroduce this endangered subspecies to its normal range.

The Mexican grey wolf was almost extinct by hunting, trapping and poisoning but the US and Mexican authorities are putting efforts to reintroduce them to the wild. Mexican gray wolves are among the endangered species in the country. In 2011, Mexico started reintroducing wolves into the wild.

According to a survey published in January by the US Fish and Wildlife Service, there were 83 Mexican grey wolves existing in the wild in Arizona and New Mexico.

The genetic material for this purpose was taken from two wolves in captivity, Ezita, a female from a zoo in Tamatan, Mexico, and Perkins, a male from the Endangered Wolf Center in Eureka, Missouri. Artificial insemination was used because Ezita was already 11 years old and had had problem in conceiving naturally in the past because of physical problems.

Presently, Mexican and US officials are working on increasing the population of the Mexican gray wolf species. The last five known Mexican gray wolves were caught and it was bred in captivity by the U.S. Wildlife officials in the late 1970s. The same was done by Mexico but US first released the species in the wild in 1998 whereas Mexico released them in 2011. However, efforts are going on but the Mexican gray wolf remains an endangered species in the United States and Mexico.