Below (1979) reported that the International Bird Pellet Study Group listed 18 orders comprising 67 families and 316
species of birds that cast pellets. Of these, 129 (41%) species were Falconiformes (vultures, hawks, eagles, buzzards
and falcons) and Strigiformes (typical owls). This does not include 11 species, including a skimmer (Rynchops), thus
adding the Rynchopidae to the total number of families.