Winged cats is a term for sightings or descriptions of cats with wing-like appendages. There are three different causes of wing-like appendages. The most common is longhaired cats having matted fur. Felted mats of fur can form along the body and flanks if a longhaired cat is not properly groomed. Less commonly, mats can occur in shorthaired cats if molted fur adheres to growing fur over several seasons. When the cat runs, the mats flap up and down giving the impression of wings.
The second explanation of reports of winged cats is a skin condition called feline cutaneous asthenia or FCA, which is related to Ehlers-Danlos Syndrome (elastic skin) in humans. In winged cats that are due to FCA, the wings only occur on the shoulders, haunches, or back. Winged cats that are due to FCA can often actively move their wings, suggesting the presence of neuromuscular tissue within the wings, which is not present within clumps of matted fur alone.
The third explanation is a form of conjoining or extra limbs. These non-functional or poorly functional extra limbs would be fur covered and might resemble wings, as in one winged cat case recently documented by Dr Karl Shuker, in which the wings were shown to be vestigial supernumerary limbs.
There are more than 138 reported sightings of animals claimed to be winged cats, though some of these are clearly nothing more than individuals with clumps of matted fur. There are 28 documented cases (with physical evidence) and at least 20 photographs and one video. There is at least one stuffed winged cat, but this may be a nineteenth century fake or "grift". An undated taxidermy specimen in poor condition can be found in a museum in the Niagara Valley. It has bony structures near its shoulder blades covered with flaps of skin. These might be extra limbs.
Because these "wings" or matted fur can be moved, cats can sometimes use their appendages the way a flying squirrel uses theirs and glide from great heights.
"A few years before I lived in the woods there was what was called a 'winged cat' in one of the farm-houses in Lincoln nearest the pond, Mr. Gillian Baker's. When I called to see her in June, 1842, she was gone a-hunting in the woods, as was her wont ... but her mistress told me that she came into the neighbourhood a little more than a year before, in April, and was finally taken into their house; that she was of a dark brownish-grey colour, with a white spot on her throat, and white feet, and had a large bushy tail like a fox; that in the winter the fur grew thick and flattened out along her sides, forming strips ten or twelve inches long by two and a half wide, and under her chin like a muff, the upper side loose, the under matted like felt, and in the spring these appendages dropped off. They gave me a pair of her 'wings,' which I keep still. There is no appearance of a membrane about them. Some thought it was part flying squirrel or some other wild animal, which is not impossible, for, according to naturalists, prolific hybrids have been produced by the union of the marten and the domestic cat. This would have been the right kind of cat for me to keep, if I had kept any; for why should not a poet's cat be winged as well as his horse?" - Henry David Thoreau