How does Resa becoming a swift reflect on her character in "Inkdeath"?

Question

In Inkdeath, the third book in the Inkheart trilogy by Cornelia Funke, Resa uses seeds that turn the user into an animal. In Resa's case, she turns into a swift:

It was easy to fly, so easy. The skill of it came with the body, with every feather and every delicate bone. For the seeds had turned Resa into a bird. The transformation caused painful spasms, which had terrified Lazaro the Strong Man, but she hadn't turned into a magpie like Mortola. "A swift!" the Strong Man had whispered when she flew to his hand, dizzy to find everything suddenly much larger.
_{Inkdeath, chapter 61: "Clothed and Unclothed"}

In Inkheart, the animal that the user of the seeds turns into reflects the user; for instance, Mortola turned into a magpie, and apparently a boy that Mortola experimented on turned into a dog. How does the fact that Resa turned into a swift reflect on Resa's character?

Answer 1

Historically, swifts were mostly known for their habit of continuous flight, very rarely touching the ground - they were even believed not to have feet at all, as reflected in their scientific name (Apus apus, meaning without feet). A non-breeding common swift can spend up to ten months continuously flying Common Swift. This is reflected in the heraldic form of the swift knows as a Martlet, which often appears on coats of arms. As a bird that was seen to expend continuous effort to stay permanently aloft, it became an allegory for continuous effort, and has also been seen to symbolise a constant quest for adventure Martlet. Common swifts are migratory, and will travel from Europe or Asia to Africa for the winter; thus you can see them as embodying a form of wanderlust.

Ever since Resa was read into Inkheart and then kept in Capricorn's village she has striven to return to her family - she keeps a picture of them with her, and celebrates all her daughter's birthdays, as well as attempting to escape multiple times. This constant goal of hers could thus be reflected in her swift form. We also know she is fond of adventure stories, which again could be reflected in her swift's form. Most likely, though, the form tells of an escape from prison - after spending so many years as a prisoner with just her heart yearning for freedom, how body can now follow suit, and is no longer even bound to the earth.