I don't know if such a list exists, but it might be useful to have a sticky list of all species that require photos of male, female, juvenile and alternate plumages.
I'm sure that many Birdforum members would be willing to upload their excellent images to assist others using Opus as a resource to help identify the birds that they have seen or photographed. I also suggest that Opus be highlighted in this context. It is an excellent and highy important resource in this area.
Another idea I have, which would take many hours of dedicated work to fulfill, is to add information about moult states and migration timetables, information that seems to be lacking in many field guides. I have a great deal to learn, but would volunteer to help with "grunt" work in that capacity.
I'm sure that many Birdforum members would be willing to upload their excellent images to assist others using Opus as a resource to help identify the birds that they have seen or photographed. I also suggest that Opus be highlighted in this context. It is an excellent and highy important resource in this area.
Another idea I have, which would take many hours of dedicated work to fulfill, is to add information about moult states and migration timetables, information that seems to be lacking in many field guides. I have a great deal to learn, but would volunteer to help with "grunt" work in that capacity.