CODA
I include here a some of our Yellow-crowned’s family members found here in years past. The only way I have seen the Black-crowned here is flying away when I inadvertently disturb these hunched over bumps-on-a-log. The Great Blues usually see me first and fly away; this immature one was less wary and merely repaired to a tree. The Snowies showed up here in the drought year of 2012 and like the Yellow-crowned are seemingly less skittish then these other herons.
About names
These Yellow-crowned are not really Night-herons as you can see from from photos. They are quite active in the day. They used to belong to the same genus, Nycticorax, as the Black-crowned Night-herons and others but now they have their own genus Nyctanassa. with Nyctanassa violacea violacea the migrating sub-species breeding in the SE US, wintering in the Caribbean and South America. They still retain the ‘Night-heron’ in the official AOU name. At audubon.org we learn:
In late summer, a few wander far to north. Strays from western Mexico reach southwestern United States.
If ours are from Mexico, they are Nyctanassa violacea bancofti and in Spanish are called ‘Garza-nocturna Coroniclara’, ‘pedrete corona clara’ o ‘Martinete Coronado’. The differance between the two sub-species is slight if not purely subjective. Mainly the difference is that they have separate territories and N. v. bancrofti does not migrate.
I have been careful not to call the juveniles ‘Yellow-crowned’ (though I believe them to be so) but little brown herons or just juveniles because from what I see in descriptions and pictures in the resources they look like Black-crowned juveniles (yellow lower bill and larger spots) but are associated with Yellow-crowns and are about in the daytime. I don’t know.