Could it be the Hooded Swan series?
When the girl is later kidnapped by her own kind and taken to the Anacaona's home world, the Hooded Swan is sent to retrieve her. They fly to Chao Phrya, a world settled by a human generation ship, the Zodiac, whose descendants now believe it is their promised land, despite the presence of the Anacaona.
The kidnappers manage to land illegally in the jungle before Charlot can get permission from the uncooperative locals, who eventually agree to let the Hooded Swan land. Charlot chooses Grainger and Eve to join the local search party, which consists of two humans, Max and Linda, and three Anacaona, Danel, Michael, and Merce. As they travel, Grainger discovers that the Anacaona have minds adaptable to an almost absurd degree, and create completely human personalities simply to interact with humans.
It lacks a talking swan, but the idea of Cygnus the Swan and generational ships are present. As well as a child who is in peril.