How does Speare use color and the analogy of a bird to describe Kit in Chapter 12 of The Witch of Blackbird Pond?

In Chapter 12, Kit helps Nat repair Hannah Tupper's roof.  They talk about her new life in Wethersfield.  Nat tells her a story of a bird he saw at a market in Jamaica when he was a little boy.  The bird had been colorful, and young Nat had wished to purchase it and take it home to Connecticut.  His father had persuaded him not to, telling him that "it wasn't meant to live up [in...

In Chapter 12, Kit helps Nat repair Hannah Tupper's roof.  They talk about her new life in Wethersfield.  Nat tells her a story of a bird he saw at a market in Jamaica when he was a little boy.  The bird had been colorful, and young Nat had wished to purchase it and take it home to Connecticut.  His father had persuaded him not to, telling him that "it wasn't meant to live up [in Connecticut], that the birds... would scold and peck at it."  Nat then tells Kit that he was thinking of that colorful bird when she left the ship the first day in Wethersfield.  She had her colorful clothes on and she had gone to a place that was not her home.  He had been concerned that she would not fit in living in dull and dreary Wethersfield.

Nat tells Kit that her family and the others in Wethersfield had "done their best to make [her] into a sparrow."  He goes on to say that he "can still see the green feathers if [he looks] hard enough" at her.