"At least eight Chinese crested terns - a species once suspected to have been extinct - were discovered on a Matsu islet in June," a spokesman for Taiwan's Council of Agriculture said.
The birds have built four nests on the islet, which is already listed as a bird sanctuary by the Taiwanese government, and there are four fledglings, the official said.
The Matsu island group is just 9,8 kilometres (5.8 miles) from China's Fujian province.
The birds were found by Taiwanese photographer Liang Chieh-teh.
He warned that the rare birds could disappear if no special protective measures were taken.
Liang said a number of Chinese fishermen poached bird eggs from the Matsu island group.
Some 2 000 other terns, along with the rare species, nest in the sanctuary. - Sapa-AFP