This was a one-page ultra short story, maybe three paragraphs. I read it no later than mid-80s in a random story collection and it was probably a lot older than that.
There isn’t much to it:
An alien spaceship lands on some empty place and an alien being emerges. Some curious prairie dogs pop up to see what’s going on, and the alien(s) immediately kill them for sport.
Suddenly a hidden turret comes up from underground and destroys alien and ship in one blast with a futuristic weapon. One of the prairie dogs operating the turret quips to its companion: “funny, I always thought the humans would be the first ones to try.”
I can’t remember the book, story title or author. Weirdly, I came up empty when searching on the internet. You would think this would be easy to locate.