As their environment became colder and wetter (possibly because of their migration), the birds evolved many traits to help them survive in the changed environment.
(their environment; became; colder and wetter; possibly because of their migration) (many traits; to help; them survive in the changed environment) Context(many traits to help,List([103, 122))):(them; survive; L:in the changed environment)
many traits to help,List([103, 122))
their environment many traits them
became to help survive
colder and wetter possibly because of their migration
them survive in the changed environment
L:in the changed environment