A total of 23 hm² of fishponds and 22 hm² of cultivated lands in the New Territories of Hong Kong Special Administrative Region (HKSAR) were converted to two flood control channels (Channels 60 and 43) by the Main Drainage Channels Project for Ngau Tam Mei, Yuen Long, and Kam Tin (MDC Projects). Post-construction ecological monitoring surveys showed that bird abundance of the two flood control channels were lower than those of the habitats they replaced. Conversion of cultivated lands to Channel 43 resulted in decline of mean bird density from 33.9 individuals/hm2 to 2.2 individuals/hm². Conversion of fishponds to Channel 60 resulted in decline of mean bird density from 5.2 individuals / hm² to 0.4 individual/hm². This was probably due to declines in food abundance, vegetation cover and habitat complexity. Losses of ecological habitats were observed. The inner embankment of Channel 43 was lined with grasscrete to provide wildlife habitats to mitigate the loss of cultivated lands. This mitigation measure, however, proved ineffective.