A couple cattlemen around me still do it...I'm just outside of Tulsa. It doesn't bother me when a farmer or rancher does it. Yeah it's ugly, but it just seems "Oklahoma-ish". I think they used to do it for a variety of reasons. A rancher would do it to show the neighbor he got a coyote, and hunters with permission to hunt would do it to show the land owner they are successful.
I also like the flatheads on t-posts. Now I think it's way trashy and redneckish and I would never do it...but again it's part of Oklahoma's charm to be driving down a country road in July or August and see rows of giant, shriveled up fish heads staring skyward for eternity. Brings to mind a bunch of fat, shirtless dudes with rebel flag tattoos drunk on cheap beer and frying fish next to a Trans Am with Skynyrd on the 8 track. In other words, it feels like home.
HAHA Home sweet home! I used to always cut off a pig's ear if I shot it in the pasture and hang it on the gate for the rancher to see so he knows I'm not falling down on the job. I had quite a collection till the varmints found them.