Very well done! I like the BG and the way you controlled the whites. The eye detail is good. I would wish for a bit more room to the right and just a tad of head turn toward you.
The other have covered the technical comments. So I will add to comments on composition. I think this presents well as a portrait as you have just the right amount of space for the bird no to feel too cramped ( my opinion). The white contrasts well with the dark green background. Thanks for sharing.
Personally the BG is too dark (just my personal taste) and a bit more brightness wouldn't hurt.
Nice detail and colors on the egret though.
Congratulations!
I agree about another round of noise to the BG. I love the composition and you did a superb exposure job. A different option to considere is to lighten the BG a bit to made the gree pop-up a bit.
Those bright white birds on a dark background are a tough exposure but you have done an ecellent job controlling the white. Good sharp image as well. The head does appear square to the camera but because egrets eyes tend to look foward it appears as if the bird is slightly looking away which has loss some eye contact for the viewer. Overall a very nice potrait indeed.