FOUR HERONS

I was told recently that poems about birds are out of fashion, before this it was the word shard. I am not sure who decides such things, certainly they do not matter.
Here is a poem that mentions herons. It is far from finished, but I think it works in its own way.

Four herons pick over the bones,

clack and caw to reach a decision.

The city is their backdrop.

Sunlight gilds the water.

The herons have set themselves a task,

to sieve the river from end to end.

They argue. This one complains:

I am no pelican, gimlet of eye

With a shovel bill and appetite to match.

Another talks technique,

the proper motion for investigation,

the beak must rise and fall, rise and fall.

A third interrupts attempts to compare the action

to a sewing machine’s needle tip,

glimpsed once through a window,

but language fails, then there is argument.

Crepuscule stains the surface blood…

This is how to sift a river:

start at the mouth, as if French kissing,

note how the current probes back.

As you move up stream

silt may stain, smooth pebble chip tooth.

Gold may gather on your tongue.

Whatever they say,

whatever is promised,

this is a misfortune.

Once the gold has been possessed,

the water strip searched

it’s bed disturbed and left unmade,

there will be nothing.

You cannot now tell the herons apart,

they are a jumble of feather and bone.

The city has been put to the sword.

Oh yes, someone is the richer,

but not you, not yours.

We few that remain,

plum the dirty stream for anything.

I'd be interested in your opinions. I know what I think the poem is about but you may have different ideas.
I leave you with a song from 1980. I used to have the single.