Terns that fly in to lay eggs on remote islets during summer are under threat because of growing intrusion by photographers, the Hong Kong Bird Watching Society says.
The society says the Agriculture, Fisheries and Conservation Department has turned a blind eye to the worsening problem and urges a ban on visitors landing on islets that are prime breeding grounds of the seabirds.
Many terns that breed in temperate zones are long-distance migrants, travelling north or south to their wintering territories after breeding is completed.
In Hong Kong, terns are commonly found on islets such as Port Island, Kung Chau, and Shek Ngau Chau in northeastern waters during the breeding period between May and September.
The Bird Watching Society has visited the islets regularly since 1998 to monitor the tern population.
One member, Alan Chan Hin-lun, said that in recent years they had encountered increasing numbers of photographers landing to take pictures of the birds.
"The terns were scared off, leaving behind their eggs and babies in the nest," Chan said. "It is a great disturbance to the terns."
He said society workers had asked the photographers not to disturb the terns, adding: "They did not seem to care. We were told not to be nosy."
The society said it had raised the issue with the department and formally filed one complaint last year, but so far had received no reply.
Similar disturbances were found this year.
"There are many things the department can do, like declaring the terns' breeding places a restricted area and banning visitors," Chan said. "At least, it should step up promotion and education to tell people that it is illegal to disturb these birds."
In Hong Kong, all wild birds, including terns, are covered by the Wild Animals Protection Ordinance. Any person who disturbs or injures wild birds or their nests and eggs is liable to a maximum fine of HK$100,000 and a year in prison.
The department said it had set up warning signs on known tern breeding sites to advise visitors not to disturb the birds.
Its guidelines on watching terns also advise visitors not to land on the tern islands during the breeding period and to watch the birds from a boat at least 20 metres from the breeding site.
According to the department's count, the number of terns found in Hong Kong during the breeding period has increased from 1,000 last year to 1,400 this year.
Most commonly found on the small islands around Hong Kong are the black-naped tern, bridled tern, and roseate tern.