I am a wildlife photographer, i was in the parking area of the totagatic wildlife refuge by myself, about 7-miles west, northwest of hayward wi at 8.10 pm calling in wolves via a digital sound producing device. sun had set but it was still quite light out, i could easily glass the flats of the totagatic river(where the wolves were expected come from). sky was still light blue, no stars apparent, though the moon was up and just behind my left shoulder as i was facing toward the west northwest. sky was clear and crisp, but for some elongated, wispy, very high altitude clouds which were moving fairly swiftly west, southwest. something caught my eye as i paused glassing for wolves, and i had looked up toward the thin, wispy, rolling type clouds as they passed over me. what had caught my eye was small golfball sized object just my side of the cloud i was looking at. it was dark and going more into the sunset then not, moving with the cloud. i observed it via a nikon 10 x 50 set of binoculars, my observation went on for about 15-20 minutes. my first thought was it was a piece of the cloud, breaking off, it looked like the cloud, its horseshoe/u shaped structure was oriented in such fashion as i was looking at the open end of the u. it literally appeared as a cloud, same wispy structure, like swirling cloud about its projected shape as it moved, slowly across the sky. while it moved with the clouds at points, it never moved to the west/southwest as they did, this was what had caught my eye, its movement was always west, northwest! however it immediately became apparent this was an actual object, which appeared to be slowly flitting cloud to cloud, and doing its best to blend with them. it's shape never wavered, which is how and why i came to identify it as an aircraft of some type i had never observed before. it exhibited no other unusual movement other than it was plainly moving cloud to cloud in an otherwise very clear sky. no navigation lights were observed, it emitted no plume, or con trail, if not for the obvious static shape of the object it would have easily passed for a small part of cloud breaking from another cloud! it appeared to slow several times and wait on a cloud, it could have been hovering at several points but such was hard to establish at my observation point! i watched it until it vanished within a cloud off to the west/northwest! at no point did it change its shape, structure was readily apparent, and it was more u-shaped than horseshoe. it appeared to have a layer of wispy cloud cover covering its shape, but not breaking it up entirely. it was clearly under intelligent control and stealthy in its movement and actions. it could have been a drone, but at that altitude it would have been awfully big, it would have been larger than a commercial airliner. just a few moments before making observations i had seen a private jet fly off toward the setting sun, as it had just departed hayward's private strip, probably a 6-10 passenger lear. i served on the uss saratoga(cv-60)with va-105 light attack squadron and i know what aircraft look like from all angles and altitudes. this device was clearly unconventional in shape, and via its unusual cloud to cloud maneuvering, it was obviously stealthy in that it was using clouds to blend with.....