Wolfdogs display a wide variety of appearances, ranging from a resemblance to dogs without wolf blood to animals that are often mistaken for full-blooded wolves. A lengthy study by DEFRA and the RSPCA found several examples of misrepresentation by breeders and indeterminate levels of actual wolf pedigree in many animals sold as wolfdogs. The report noted that uneducated citizens misidentify dogs with wolf-like appearance as wolfdogs. Wolfdogs tend to have somewhat smaller heads than pure wolves, with larger, pointier ears that lack the dense fur commonly seen in those of wolves. Fur markings also tend to be very distinctive and not well blended. Black-colored wolfdogs tend to retain black pigment longer as they age, compared to black wolves. In some cases, the presence of dewclaws on the hind feet is considered a useful, but not absolute, indicator of dog gene contamination in wild wolves. Dewclaws are the vestigial first toes, which are common on the hind legs of domestic dogs but thought absent from pure wolves, which only have four hind toes.