Hong Kong Sparrows Wing Back To Stable Levels

The Hong Kong Bird Watching Society says the city's population of sparrows rebounded this year to what it considers a stable level.

The society has been conducting city-wide censuses of the Eurasian Tree Sparrow in Hong Kong for four years, and the latest estimate puts the species' population at 300,224 – comparable to the estimates for 2016 and 2017.

This year's estimate is also up more than 20 percent from last year's number of 256,287. The society suggested last year's drop was closely related to the abnormally dry weather then.

Dr Pang Chun-chiu, a senior research specialist with the society, said they had speculated then that the birds had either postponed their nesting season or the dry weather had affected the birds' survival.

He said this year's rebound suggests the first hypothesis was correct, and the sparrows were just "hidden" from plain sight last year.

"This year provided us with good evidence that the birds might have some flexibility in adjusting their breeding season and they have some behavioural adaptability to the abnormal weather condition or even to some changes in the cityscape in Hong Kong," said Pang.

He told RTHK's Richard Pyne that sparrows are a good bio-indicator of how friendly the city is to nature.

"So, the number might help us to evaluate, to think about whether we are doing something good to the species, to the neighbourhood," he said.

However, the society was also concerned that some residents were asking for sparrow nests to be removed, as they consider the birds a nuisance or hygiene risk. It says all birds are under legal protection in Hong Kong, and removing birds' nests is against the law.

Pang said there are ways to reduce the inconvenience the birds pose, for example, by installing trays under nests to catch droppings.

"The breeding season won't last really long, they're only covering four months a year ... so we can try to tolerate to protect the breeding season of the birds."