The Intermediate Egret (Ardea intermedia) is a stocky egret that is larger than the Cattle Egret and the Little Egret, but smaller than the Great Egret.
Often confusing and difficult to identify, this bird is truly intermediate between potential confusion species.
Things to look for include a yellow bill that is shorter than Great Egret but longer than Cattle Egret, a relatively rounded head, and shorter legs than Great Egret, approaching Cattle Egret.
A reliable difference between the Great Egret and the Intermediate Egret is that the Great Egret's gape line extends behind the eye, while the Intermediate Egret's gape line is less pointed and ends below the eye. 
In Asian populations the bill becomes black during the breeding season; these birds can be distinguished from the Little Egret by their completely black feet and shorter bills. 

There are three subspecies:

1. the so called "Yellow-billed Egret" (Ardea intermedia brachyrhyncha) from sub-Saharan Africa;
2. the so called "Intermediate Egret" (Ardea intermedia intermedia) from Asia; and
3. the so called "Plumed Egret" (Ardea intermedia plumifera) from New Guinea and Australia.

Sungei Buloh Wetland Reserve, Singapore, 8 November 2022