XI'AN -- Four crested ibises were born in a nature reserve in northwest China's Shaanxi Province, authorities said Wednesday.

The rare birds were born at the Shaanxi Hanzhong Crested Ibis National Nature Reserve. It was the first group of crested ibises born at the reserve this year, more than 20 days earlier than previous years due to unseasonably warm temperatures.

The nature reserve sits in the southern part of the Qinling Mountains, with more than 210 crested ibises being raised. Currently, 10 pairs of the birds are hatching in their nests.

The crested ibis, with its iconic red crest and long black beak, was thought to be extinct in China until seven wild birds were observed in Shaanxi in 1981, a discovery that prompted captive breeding and enhanced protection of the species.

It is estimated that there are more than 5,000 crested ibises in the world today, and about half of them live in Shaanxi.