This family of insect and seed-eating, ground-nesting birds resemble partridges, but with featherless heads, though both members of the genus Guttera have a distinctive black crest, and the Vulturine Guineafowl has a downy brown patch on the nape. Most species of guineafowl have a dark grey or blackish plumage with dense white spots, but both members of the genus Agelastes lack the spots (as do some domestic variants of the Helmeted Guineafowl). While several species are relatively well known, the Plumed Guineafowl and the two members of the genus Agelastesremain relatively poorly known. These large birds measure from 40–71 cm (16–28 inches) in length, and weigh 700–1600 (grams) or 1.5-3.5 (pounds)