On November 3, 1994, approximately 1045 hours mountain standard time (mst), a Piper PA-18-105, N7566K, registered to John F. Christensen, and being flown by the owner's son, John O. Christensen, a private pilot, was substantially damaged when the aircraft descended into downsloping terrain and then nosed over approximately 37 nautical miles south of Gillette, Wyoming. The pilot was uninjured. Variable meteorological conditions existed at the time of the accident and no flight plan had been filed. The flight, which was an aerial observation of cattle, was to have been operated under 14CFR91, and originated from the pilot's ranch near the accident site approximately 0945 hours. The pilot reported that there was an estimated ceiling (overcast) of 1000 feet (above ground) and a visibility of 2 miles. He also stated that the ground was snow covered and that "contrast was poor due to (the) fresh snow on the ground." He reported that while checking cattle he observed two coyotes and maneuvered to get a better look. While observing the animals out the right side of the aircraft, and with the aircraft in a glide over descending terrain, the wheels touched the snow and the aircraft nosed over.