I know this post is not about hummingbirds but a pollinator none the less. Hope that is okay Bob?
The video on the bumblebee is interesting.
[Bob here. Yes, it is perfectly OK to post this. I just added "Off Topic" to the message title]
Thanks for sharing this! We don't have the Rusty Patched Bumbles here in the PNW of course, but I've seen similar kinds of disappearances in my own garden at least. When I first started gardening for wildlife here 30 some odd years ago, I regularly had 4 species of bumbles in my garden any given year. Last year I had two. But at least with the bumbles, it varies from year to year which ones I have or don't have.
More depressing is that one year I had a native Mustard White Butterfly, which is supposed to be one of the more common whites in our area. I haven't seen one in almost twenty years now. At the time I didn't think too much of it, but didn't know what to plant for the caterpillars either. By the time I realized it was gone, planting the native mustards it uses to lay it's eggs on has been rather useless. I continue to grow them where I can just in case... So many of the native bugs use native "weeds" that get eradicated with the domestication of the landscape, and we loose so much of our biodiversity through "cleaning things up"...
Personally I think whoever linked the old phrase "cleanliness is next to godliness" with gardening should be shot. The leaf piles and weed patches harbor far more life than the carefully mowed and edged lawn.