Nettle-tree butterfly sighting in Sha Tau Kok a first for Hong Kong

A butterfly never seen in Hong Kong before has emerged in the border town of Sha Tau Kok, a formerly closed area that is becoming known as a butterfly haven among nature lovers.

The sighting of the European beak, also known as the nettle-tree butterfly for its unique "hooked" wings, is further proof of the ecological value of Sha Tau Kok - already home to more than half of all locally known butterfly species, environmentalists say.

James Hui Chun-tung, a retiree who used to work in marine biology and protection, spotted the insect next to a stream near Hung Fa Leng, also called Robin's Nest.

"I was really overjoyed to find it, and also encouraged," said Hui, 62. "Butterflies in Hong Kong have decreased in numbers so drastically. There used to be more than 10,000 living through the winter in Hong Kong. Now, only hundreds are left."

Hui snapped two photos showing the European beak, the first photographic record of the butterfly in Hong Kong.

The European beak feeds on nettle trees, which are common in the city. It prefers cooler climates and can be found on the mainland, in Taiwan, Japan and parts of Southeast Asia.