Your poem is like a painting with words. I cannot decide which lines that I like best. It is either:

The water near the shore is uncommonly still.
Reflecting an uncertain sky like a mirror.
Small clouds stirred by an impatient breeze.

or

Below, the blazing-white egrets,
set against lesser and envious hues,
eagerly search for their evening meals.

Very well done.

Hello, Michael,
Such a beautiful title. Serenity from the first word. I love to watch egrets and cranes - you've described their patience and elegance so well. A touching final line, the giving nature of the shallow waters. The precise timing and natural connection with nature is remarkable.
Thank you,
L

visions of serenity and a knowledge of the way that the graceful egrets move.
I see this in the lines "Their spindle-like legs, lifting gracefully and purposefully, one after another"
Anyone who has ever seen them, will recognize their movement. I have just a thought or two about the line
"Reflecting an uncertain sky like a mirror", and "to find what their host seeks".

It seems to me, that the use of uncommonly and uncertain within two lines so close might just seem a little awkward.
You might use something like [ a flat grey sky ] or something similar. I think that you take away from the really good lines
before, of "Their spindle-like legs, lifting gracefully and purposefully one after another in concert",
with the use of "To find what their host seeks". ~ Geez.
.