Warning: anecdote to follow. Data set: n=1.
Not a peer-reviewed study. Just a completely irrelevant observation by a completely irrelevant HN poster.
But, yeah, I'm inclined to believe this. I live a few hundred meters (yards in Freedom Units<tm>) from two major highways.
Last year, at the tail end of the pandemic-induced lull in traffic, my flowers would attract groups of over 20 bees, easily, every day.
This year, with similar weather, pretty much the same flowers, and definitely the same location, it's a good day if I see 4 individual bees.
So, the answer 'air pollution' to the question 'what changed' seems at least likely?
But, yeah, I'm inclined to believe this. I live a few hundred meters (yards in Freedom Units<tm>) from two major highways.
Last year, at the tail end of the pandemic-induced lull in traffic, my flowers would attract groups of over 20 bees, easily, every day.
This year, with similar weather, pretty much the same flowers, and definitely the same location, it's a good day if I see 4 individual bees.
So, the answer 'air pollution' to the question 'what changed' seems at least likely?