What theme about tradition and community does this poem convey?

Read the poem "Without Title" by diane glancy.

It's hard you know without the buffalo,
the shaman,[1] the arrow,
but my father went out each day to hunt
as though he had them.
He worked in the stockyards.
All his life he brought us meat.
No one marked his first kill,
no one sang his buffalo song.
Without a vision[2] he had migrated to the city
and went to work in the packing house.
When he brought home his horns and hides
my mother said
get rid of them.
I remember the animal tracks of his car
backing out the drive in snow and mud,
the aerial[3] on his old car waving
like a bow string.
I remember the silence of his lost power,
the red buffalo painted on his chest.
Oh, I couldn't see it
but it was there, and in the night I heard
his buffalo grunts like a snore.