Question

I don’t understand the last part ‘But not one man that I …….. as thanks his God with every note’ can you explain for me,and I want to know the main theme of the following poem, is that about a strong connection between nature and people .I have to talk about the Australian vision referring to the good relationships between nature and people can I use this poem?

MAGPIES
Along the road the magpies walk
with hands in pockets, left and right.
They tilt their heads, and stroll and talk.
In their well-fitted black and white

They look like certain gentlemen who
seem most nonchalant and wise
until their meal is served - and then
what clashing beaks, what greedy eyes!

But not one man that I have heard
throws back his head in such a song
of grace and praise - no man nor bird.
Their greed is brief; their joy is long.
For each is born with such a throat
as thanks his God with every note.