For the first time， Global Positioning System trackers have been used by the Heihe Wetland National Nature Reserve in Zhangye City， Gansu Province， to monitor the path of black storks （鸛） and protect their population.

Two black stork chicks have been fitted with GPS trackers that can generate （產(chǎn)生） real?time images showing the birds locations， and the staff at the reserve can check them anytime by cellphone， says Shan Guofeng， an official with the administration of the nature reserve.The Heihe Wetland National Nature Reserve in Northwest China， covering an area of about 41，000 hectares， is an important breeding ground， habitat and stopover place for wild birds.

According to the latest statistics， 218 species of birds， including many rare ones， have been spotted in the reserve， up from 155 in the 1990s. During a bird survey conducted in the reserve last year， a total of 627 black storks， a species under first?class state protection， were sighted， a number rarely seen for a single observation of black storks in China.

Before attaching （系上） the trackers， the researchers also measured the height and weight of the two baby birds. The measurement taken， while the parent bird was away from the nest， is for ensuring free and safe movement of the birds while wearing the tracker. With GPS devices and cameras monitoring， the reserve has obtained a large quantity of data about black storks.

“I enjoyed my time with these black storks， and hope we can better protect them through systematic research，” Shan says.

[Reading][Check]

Whats the function of the GPS trackers on two black stork chicks？