Newsletter No. 35

CUHK Newsletter No.35 October 1992 Bi rds of the CU Campus Richard Lewthwaite VOICES W hen a TV news report was broadcast last February featuring the Chung Chi pond as a site for a large flock of wintering birds, colleagues were suddenly full of questions about birds. What were these birds doing on campus? What other bird species are there on campus? Are any of them rare? Which parts of the campus are best for birds? How many active birdwatchers are there? And so on. I ' ll try to answer some of these questions here and describe certain features of bird-life on campus. First, the birds that created ail the interest were a flock of over 250 Little Egrets and 20 Great Egrets. Apparently it was the first time such a flock had ever wintered on campus. After spending the day-time in Tolo Harbour, they returned each night for four months to the Chung Chi pond to roost in the acacia trees behind the Fong Shu Chuen Building. Although the TV report concentrated on the beautiful spectacle of these long-necked, white-plumaged birds gliding over the Chung Chi pond, the sad truth is that their appearance on the campus is almost certainly the result of habitat destruction in the region. Only something like the development of an established wetland area could have caused a wintering flock of this size to suddenly appear in a rather marginal area like Tolo Harbour. It's also a reminder that the campus has an important role to play in terms of local conservation. Wh i le there are no globally threatened species on the campus, there is certainly one resident population that is locally important and worth protecting, though, rather ironically, it has been attracted by the concrete of the central mall. I'm sure everyone has noticed the large number of nests under the eaves of the University Library and the twittering birds that rush in to occupy them. Several hundred pairs of House Swifts have attached their nests to the cliff-like library walls in what is believed to be the largest swift colony in Hong Kong. House Swifts have the unusual habit of occupying their nests all year round and not just during the breeding season. Their diet is entirely made up of small insects which are taken on the wing in vast numbers. A British study of the closely-related Common Swift showed that one bird consumes up to 20,000 flying insects per day. The swift colony at the University Library is therefore probably responsible for eliminating 10 million mosquito-sized insects per day. Unfortunately, a natural pest-control service of this size does not come entirely free. Complaints about droppings at one time led to the Buildings Office taking active steps to eradicate the colony, though this threat seems now to have receded. Turning to other birds on the campus, the most common ones are those that can adapt to a garden-type habitat and also tolerate some disturbance. They include Chinese Bulbul, Fork-tailed Sunbird Chinese Bulbul 4