I'd like to float an idea past the forum, if you'll indulge me...my apologies to those not interested in photographing birds.
The British Trust for Ornithology has been running a survey of birds exhibiting abnormal plumage since 2011. You can find the link to it here:
Abnormal Plumage Survey | BTO - British Trust for Ornithology
I'm sure each national equivalent will be doing something similar. The aim is to understand the distribution of abnormal plumage and the reasons for it.
The thing is, those unusual specimens do not always have the good sense to pose in front of good glass. Generally all the BTO has to go on is mobile phone shots. We must be able to do better.
So, what does everyone think? Could we rise to a Monthly Challenge, with everyone scouring their archives? Is it a new thread, perhaps?