What is the difference between a 'juvenile' and an 'immature'?
When in doubt use 'Immature' for any bird that is not an adult. 'Juvenile' is more specific, describing a bird still in its juvenile plumage. This plumage is held only briefly for many songbirds (just a few weeks after leaving the nest) or up to a year for some larger birds like hawks. Once a bird has molted out of this plumage it is no longer a juvenile. If you can't determine this, but know that the bird isn't an adult, just use 'Immature'.