Screaming or howling in Conejos County, Colorado

In the first week of June, 1994, my 2 sons and I were fishing in a beaver pond on the Lake Fork of the Conejos about 1 mile upstream from where the Lake Fork of the Conejos meets with the Conejos River. It was near sunset and the sun had already gone behind the mountains. There was a sparsly forested rise toward the southwest,above the beaver pond we were fishing. Just beyond this rise was the south slope of a ridge of old growth forest. A horrible gravelly scream or yell of almost unbelievable volume came from just inside the forest at about 150 to 200 yards distance. I am an avid bowhunter of 20 years experience with all manner of big game and the sound was definitely not an elk or bear. Elk make some loud and unusual sounds but this sound was vastly different and many times louder. I noticed that a light breeze was blowing from us toward the source of the sound. If the creature had a good sense of smell, it was probably smelling us. Bowhunting experience has taught me that an elk would smell us under the same conditions. The sound had a threatening essence to it. The sound itself was kind of undescribable and seemed louder than a creature could possibly make. Whatever made the two tone scream must have one big set of lungs and a very large, megaphone size, mouth. The sound lasted about 1 or 2 seconds and was repeated three times, with a 10 or 15 second pause between each blast of noise. I was unarmed and decided since I had my sons with me I would give the creature its space. We left. I was somewhat alarmed, but would have gone to the source of the sound if I had not had my sons with me. I did go to the area of the source of the sound the next morning alone at sunrise to see if I could find tracks or other evidence of the source of the sound. I some very old large tracks in soft dirt on a flat area about 1/2 mile uphill. They were about 16" by 8" in size but too old to descern any toes or other detail and could have been bear tracks distorted and enlarged by rains and time. There was a line of about 20 of these large tracks in single file across the bare ground of this bench. Most of the rest of the soil in this area is too rocky to see the tracks of soft footed animals well. The tracks I found were at least a week or two old. I spent all morning looking the area over, hoping to find evidence, but hoping I didn't find the creature itself.