Cattle Egret with breeding plumage, stalking our back garden. Status: “resident and widespread” in Hong Kong, mostly in northern New Territories.(“Birds of Hong Kong”). The “cattle” bit cause you often see them grabbing a quick ride on the backs of Water Buffalo.
In our garden they’re rare, and usually seen lurking around our Koi Karp pond, eyeing an easy meal, not stalking grubs in the lawn. “Breeding” plumage, so maybe looking for a mate?