Thank you all for your comments and patience, and thank you, Bev, for posting the info from Decorah - my own research has come to the same conclusion, and I eventually found a post about it on the YouTube Help Forum (though I have not found anything about why YouTube chose to do this - but they are not known for answering questions):
About all I have to add at this point is the fact that each of our cams has its own channel - and therefore its own channel icon, and that we have not added unique icons for the cam channels (though we do have one for our primary Hancock Wildlife channel where many of our videos are uploaded). As a manager or admin of our various channels, when I log into YouTube, I see a list like this of the channels I can access (there are more - these are the ones I've visited most recently):
WatchingEagletsGrow is my personal page, where I upload non-HWF videos (and have uploaded a number of HWF videos over the years) - and I chose a icon/avatar for it ages ago.
So - I don't know if YouTube will undo this new "feature" or make it optional - if any of you notice that SW Florida or any of the other cams on YouTube no longer have the icon, please let me know so I can look for a way to turn it off.
And if we're stuck with this, please let me know if folks would be interested in less generic looking icons and I'll see what I can do. We could have headshots of the various adults (like mine for WatchingEagletsGrow), or something more subtle like:
That's pretty rough - if we were really using letters I'd try for something a bit more attractive, and the background would probably be invisible. It would be in a circle like the ones in my list, but I think can have a transparent background.
Anyway, let me know if you have thoughts or comments. Thanks!