You might think our more intelligent winged friends would head south for the season, but starlings prefer to hang around, knowing theres plenty of spilled grain just for the taking.
The gatherings get so large this time of year, it often looks like a column of smoke that runs for miles in the distance. In fact, just a few years ago one ongoing string flew over the same place near Amsterdam for some 45 minutes, a nonstop showing of thousands and thousands of birds.
It makes you wonder who is the special bird that gets lead a line like that...
At any rate, starlings do spread disease and otherwise wreak havoc on farms around the area. You can learn a little more about these graceful varmints here https://mdc.mo.gov/wildlife/nuisance-problem-species/invasive-species/starling-control
In the meantime, it's probably not a dark cloud you see in the distance. Just some hungry, noisy birds.