Black-crowned Night-Heron immature

This is one of the photos of the immature Black-crowned Night-Heron I found yesterday in the Canon City area. I believe it is a 2nd year or close to a 2nd year bird. It still has brown plumage but not the white streaks on the underparts or the whitish spots on the upperparts that juveniles have. Older immatures like this one approach an adult's plumage such as with the more clearly dark crown on this bird. It has an all dark bill which is more indicative of immature Yellow-crowned Night-Herons, but this bird has shorter legs and a more hunched-over posture. The leg color in my photo is washed out but the bird had clealy yellowish legs.

More pics can be seen here

Since I don't get to see many immature Black-crowned Night-Herons, any feedback on aging this bird from those with more experience would be welcome
SeEtta