I sent this different view of the same bee back to INaturalist and it's first choice was also a UCB. There are several lessons here. The first photo above is fuzzy beyond the normal of the bee's body. The view to the right shows more details including the legs which were important in the identification. Finally, when in doubt, submit to Bugguide.
I edited Patty's original 7 second video of the scuffle in a quarter speed replay at the end in this video version and asked her to describe her experience.
"I saw a bunch of these little bees poking their heads out of the ground at Busiek. While watching them one was all the way up when a second bee walked up to it and they started fighting. The tussle only lasted a few seconds and they went off in opposite directions, nobody hurt. I didn’t see them nectaring on anything specific. It was early, the 20th of March so maybe they were just venturing out of the ground into the sun."
Ground nesting bees make up 70% of all bee species world wide. They make solitary nests although they may be gregarious, having many neighbor nests of the same species in a small area. Building a nest with a open tunnel and no roof means their offspring are in danger of flooding and wet soil. Most species overcome this by creating a glandular secretions that they brush on the cell walls. This lining is a secretion product of the Dufour's gland, located at the base of the sting in female bees. They then spread this transparent, waxy coating around the brood cell, with their mouth, protecting the larva from flooding and spoiling of their nectar and pollen provisions.
|UCB Emerging in spring - see Bug of the Week - MJ Raupp|
UCB is a common species of plasterer bee (family Colletidae), native to North America. Like other species in the genus, it lines the cells of the underground nests Dufour's gland secretion but they mix it with their saliva. This dries to a smooth cellophane-like lining, giving them an alternate names of Polyester or Cellophane Bees. Cornell.edu has a lot more information including an explanation of what Patty was observing during the little clash of neighbors.
"One of the most abundant ground nesting bees in northeastern and midwestern region of North America is Colletes inaequalis. Even though this bee is solitary, meaning that every individual female builds her own nest, it is also a gregarious nester. Many females (hundreds and sometime thousands) build their nests next to each other. The nests are obvious above ground because of the conical piles of dirt with a hole in the middle."
Unlike social bees and wasps, solitary species are not aggressive
insects. Females do have a stinger but will not attempt
to sting humans unless handled. Most activity at nest sites in early
spring is of males looking for females to mate with. So Patsy's observation was probably just boys being boys.
Discover Life has a lot of high quality photographs of the UCB nectaring.