I was in the Army at the time, and stationed at Ft, Huachuca. I had an apartment off post that I stayed at with a girlfriend. Over the years, we saw at least three UFOs together, and saw several individually there in Sierra Vista. During the time that I was stationed there everyone I know saw numerous strange lights and objects in the sky.One morning, it had to be a Saturday or Sunday, my girlfriend and I went for a walk together. We wandered the length of a canal that is bordered by 7th on the West, Coronado on the East, and just barely south of Carmelita Dr, behind the houses that face North on Carmelita.We came to a perfect circle of sand, and inside of that circle was a perfectly round circle impression. I don't remember the diameter of the impression, but it was probably between five and nine feet. In the center of the circle, facing North, was a severed cow's head.The sand was out of place, since everything else around there was dirt. There were no footprints, track marks, or anything like that anywhere in the sand. I figured that whoever made the circle impression would have to have left tracks, or at least some marks into, or out of, the sand, where they walked up to the circle, or placed the head, but there was no indication that anyone had tried to cover tracks either.There were no burn marks, no other body parts, and no blood. The head was fresh, and therefore should have been bleeding, but there was no blood under the head. I walked through the circle to examine the head. There were two large ticks on the head that looked to have died while trying to feast on it. I thought that the presence of dead ticks in mid meal was just as strange as finding a head with no footprints or blood. After all, the ticks would probably not have been on a live cow, and why would they have died on the dead cow?The girl that I was with was completely uninterested. That was her standard response to everything out of the ordinary though. I found it really odd, but forgot about it until recently when I was going through some other UFO experiences that I had out there and have been reporting them to MUFON.There is nothing to say that it was related to the strange lights and experiences we were all having at the time, but coupled with the other weird things that were going on during the weeks prior to, and post, cow head discovery, I figured that it could be relevant.