The newest "manager" at Mai Po is expected to attract more birds to the nature reserve simply by munching the grass and wallowing in the mud.
He is a 10-year-old water buffalo, a stray brought in from Yuen Long. The global conservation body WWF introduced him - the third water buffalo at Mai Po - to the wetland last week. His humble labours, they say, will bring ecological benefits to the area.
"We've found that using buffaloes is more effective than no management [not cutting the grass] or manual grass cutting," said WWF reserve officer Katherine Leung Kar-sin.
The buffaloes create better habitats for waterbirds simply by existing and performing their normal, carefree daily routine.
They eat the grass, making birds feel more secure among the shortened stalks. The buffaloes trample and roll in the mud, creating puddles where some birds like to feed. The insects on their body and faeces provide food for birds. "Birds like cattle egrets stand on their backs. Some follow the buffalos around, eating along the way," Leung said.
In the part of Mai Po where grass grows wild, only five birds per hectare were counted, on average, over a period in 2006-07. Another area where the grass was cut manually had 11 birds.
Then the buffaloes were introduced: "Siu Mai" in 2006 and "Wo Muk" three years later.
The number of birds per hectare rose to 18, in 2006-07, in areas where Siu Mai was at work. "The first stage was successful, but the grass was not short enough. Perhaps Siu Mai's appetite was not big enough," Leung said.
Then Wo Muk came along and birds doubled to 39 in 2009-10. Bird diversity increased along with their numbers. The 42 species recorded in the reserve in 2006 increased to 58 in 2009, after the second buffalo arrived, a WWF study found. The new species included the oriental pratincole, northern lapwing and black-faced spoonbill.
The area with no management had 31 species recorded and that with manual grass cutting had 37.
The public will be able to meet the buffaloes at the end of November, when a new grazing area is established where the buffaloes will visit occasionally.
Siu Mai and Wo Muk have been living in an enclosed, 1.8-hectare freshwater habitat in a more protected part of the reserve. A new fence was built around the area this summer, enclosing 15.6 hectares, which will be able to hold up to 11 buffaloes. Leung said more buffaloes would be added later.
The new buffalo was taken to the extended area last Tuesday, by WWF and Agriculture, Fisheries and Conservation Department staff.
The WWF has organised a naming competition for him; suggestions will be accepted until September 28.