I blame a rat. Last year, while I was on a Burrow Blocker service job, marking ground squirrel holes with the grounds superintendent, we heard a nasty fight in one of the holes. We thought it must be some ground squirrels fighting. Soon, a bloody faced ground squirrel raced out of the hole and at the entrance we saw a red mouthed rat. The rat had won the battle and claimed the hole.
When I wrote "What's in that Hole?" for an April blog last year, I forgot to mention that rats also like to live in ground squirrel holes. The guys had told me about a Burrow Blocker service at a large dairy that had a huge ground squirrel problem. When they started filling the holes, they soon realized that there were just as many rats as ground squirrels in the holes. Like ground squirrels, rats are destructive rodents that transmit disease. Rats may not be quite as extensive with their digging, but they try, and their chewing & gnawing is a costly problem.
How do you think this ground squirrel got the new ear style? Maybe it was another squirrel or even a cat. I really don't know, but I wouldn't be surprised if it was a rat.