There is a great deal of bird imagery used in Charlotte Brontë's novel, Jane Eyre.
When Jane arrives as a governess at Thornfield, she is much like a bird: nervous and shy, caged in that she can not come and go as she pleases. Rochester refers to Jane several times by comparing her to a bird. He says that she reminds him of a bird who, if free, could soar to great heights.
I see you laugh rarely; but you can laugh merrily . . . I see at intervals the glance of a curious sort of bird through the close-set bars of a cage; a vivid, restless, resolute captive is there, were it but free, it would soar cloud-high. (Chapter 14)
Jane also experiences the sense of being a caged bird: when she walks through the orchard, the high walls and hedges are like the bars of a cage that hold her captive, providing no escape and no free movement from within the confines of the confines of Thornfield.
Physically, Jane is a captured bird when Rochester pulls her into his arms to kiss her. He is much stronger in terms of the physical and his iron will, but Jane is beginning to grow, asserting her need for freedom. In Chapter 23, Rochester tells Jane:
...be still; don't struggle so, like a wild frantic bird that is rending its own plumage in its desperation...
But also in Chapter 23, Jane asserts her independence—her need to be free—having, ironically, to have learned to be stronger under Rochester's care:
I am no bird; and no net ensnares me; I am a free human being with independent will, which I now exert to leave you..."
When Jane flees Thornfield, learning that Rochester has a mad wife (Bertha) who he keeps locked in a tower, in Jane we see the timid bird of the novel's beginning take flight. She is not sure where she will go, but she must leave the man she loves.
This time away from Rochester might symbolize an "emotional" winter—where Jane moves to a safer place with a coldness that has become her heart. However, when the frigid temperatures have passed (when Bertha, Rochester's wife, has killed herself), like a bird, Jane returns to the place where she has felt safe and loved, like a bird returning to its nest to rebuild in a new season, starting a new life.
In Charlotte Brontë's Jane Eyre, bird imagery describes to the reader how Jane is trapped like a caged bird at the beginning, how she develops the strength and bravery to take flight on her own, and how she eventually returns, as birds often do, to her "summer home" to make a home and a family.