In winter the blackbirds congregate in trees. At Farmington Bay, the last house before the Waterfowl Management Area has a huge tree that is always filled with blackbirds. I took the first picture yesterday. You can really see the difference in the sky in this picture with no inversion versus the subsequent pictures from a few weeks ago when the inversion was terrible. Salt Lake City has the dubious distinction of having same of the worst air quality in the country.
The big groups seem so frenzied because so much activity is occurring.
In the middle of all these blackbirds was a Black-Billed Magpie. I really love this shot. One calm bird in the middle of a flight of the other birds.