Etude de l'activit� prot�olytique des divers organes du syst�me digestif de quelques esp�ces d'oiseaux en rapport avec leur r�gime alimentaire

Probable evidences of bone accumulation by Pleistocene bearded vulture at the archaeological site of El Mirón Cave (Spain)

“…barbatus is known as being the only vertebrate whose diet consists mostly of mammal bones (between 70 and 90% juvenilesadults according to Cramp and Simmons, 1980;Margalida and Bertrá n, 1996). Their digestion is aided by the morphology of the oesophagus, which is elastic and expandable, and by the high acidity of their gastric juices, with a pH estimated between 0.7 and 1 (Herpol, 1967;Houston and Cooper, 1975). Small bones are swallowed directly and large ones are often dropped onto ''bonebreaking rocks'' or ossuaries until they are broken down to a digestible size.…”

Avian Physiology

“…More recent evidence from Herpol (1964Herpol ( ,1967 indicates that pepsin is present in the proventriculus of all grain-eating species investigated and even in the gizzard of certain carnivorous species such as Falco tinnunculus (falcon) and Buteo buteo (buzzard) (Herpol, 1964). Before birds are fed, the pepsinogen granules are abundant in the gastric mucosa; shortly after feeding they virtually disappear, however, indicating that they are concerned in digestion.…”

“…The alimentary tract pH of several species of birds has been determined (see Herpol, 1966Herpol, , 1967Herpol and van Grembergen, 1967). Most workers are agreed that all parts of the tract are acid, with the highest pH recorded in the intestines and the lowest in the gizzard and the proventriculus.…”