Great Spangled Fritillary, (Speyeria cybele)

We are experiencing an explosion in our butterfly population. I’ve never seen as many butterflies as I have in the past two days; every flowering shrub or plant seems covered.
For example, in these pictures that I took last night I counted 10 butterflies in the top picture and 36 in the bottom picture.

There could be a few thousand butterflies here right now.
Many of them are Great Spangled Fritillaries but I’m seeing other species mixed in.

I’ve lived here for over three decades and I’ve never seen anything like this.
I wonder if our management is causing this or if it is something else.