CPH is an opportunistic predator and often uses a "sit and wait" tactic to capture prey. So, their prey items can be big. On mudflats, they are capable to capture and swallow mudskippers (around 10-15cm?). Based on chick regurgitate, other large prey items include musk shrew, paddy frog, Chinese Forest Skink, and Bowring's Gecko (p55, Ecology of Birds of HK). So, it can swallow a large prey like tree sparrows without difficulty.
Black-crowned Night Heron is even more notorious, not only large fish like catfish and koi, but also Tree sparrow and red-whiskered Bulbul. They even prey on chicks of other waterbirds nesting nearby.....
