*  why do the  mariner change their minds about the value of the bird ?

Dear Student!

The Mariner shoots the albatross even though it is appreciated by all the sailors for helping them out of the waters of the Antarctic. However, the sailors change their minds when the mist starts disappearing. Nonetheless, as a result of killing the albatross, the ship is sent to uncharted terrirtories by the South wind. Once again, the sailors change their minds and blame the Mariner for the gruesome thirst they start feeling. As a symbolic punishment, they force the Mariner to wear the dead albatross around his neck.

Hope this answers your question.

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