Angel, C. R. (1994). Age changes in digestibility of nutrients in ostriches. American Ostrich 06 issue, 26–31.
Dawson, T. J. & Herd, R. M. (1983). Digestion in the Emu: Low energy and nitrogen requirements of this large ratite bird. Comparative Biochemistry and Physiology 75A, 41–43.
Degen, A. A., Duke, G. E. & Reynhout, J. K. (1994). Gastroduodenal motility and glandular stomach function in young ostriches. Auk 111, 750–755.
Duke, G. E. (1985). Raptor physiology. In Zoo and Wildlife Medicine, 2nd ed., pp. 370–376. [Fowler, M. E., editor]. Philadelphia: W. B. Saunders Co.
Duke, G. E. (1986). Alimentary canal: anatomy, regulation of feeding and motility. In Avian Physiology, 4th ed., pp. 269–288. [Sturkie, P. D., editor]. New York: Springer-Verlag.
Duke, G. E. (1989). Avian gastrointestinal motor function. In Handbook of Physiology – The Gastrointestinal System, Part 2, pp. 1283–1300. [Wood, J. D., editor]. Bethesda, MD: American Physiological Society.
Duke, G. E., Bird, J. E., Daniels, K. A. & Bertoy, R. W. (1981). Food metabolizability and water balance in intact and cecectomized Great-Horned Owls. Comparative Biochemistry and Physiology 68A, 237–240.
Duke, G. E., Eccelstein, E., Kirkwood, S., Louis, C. F. & Bedbury, H. P. (1984). Cellulose digestion by domestic turkeys fed low or high fiber diets. Journal of Nutrition 114, 95–102.
Duke, G. E., Evanson, O. A., Redig, P. T. & Rhoades, P. T. (1976). Mechanism of pellet egestion in Great-Horned Owls (Bubo virginianus). American Journal of Physiology 231, 1824–1829.
Duke, G. E., Jegers, A. A., Loff, G. & Evanson, O. A. (1975 a). Gastric digestion in some raptors. Comparative Biochemistry and Physiology 75A, 649–656.
Duke, G. E., Kostuch, T. E. & Evanson, O. A. (1975 b). Electrical activity and intraluminal pressure changes in the lower small intestine of turkeys. American Journal of Digestive Diseases 20, 1040–1046.
Duke, G. E., Place, A. R. & Jones, B. (1989). Gastric emptying and gastrointestinal motility in Leach's Storm-Petrel chicks (Oceanodroma leuchorhoa). Auk 106, 80–85.
Dykstra, C. R. & Karasov, W. H. (1992). Changes in gut structure and function of House wrens (Troglodytes aedon) in response to increased energy demands. Physiological Zoology 65, 422–442.
Dziuk, H. E. (1971). Reverse flow of gastrointestinal contents in turkeys. Federation Proceedings 30, 610.
Dziuk, H. E. & Duke, G. E. (1972). Cineradiographic studies of gastric motility in turkeys. American Journal of Physiology 222, 159–166.
Grajal, A. (1995). Structure and function of the digestive tract of the Hoatzin (Opisthocomus hoazin): a folivorus bird with foregut fermentation. Auk 112, 20–28.
Jackson, S. & Place, A. R. (1990). Gastrointestinal transit and lipid assimilation efficiencies in three species of sub-antarctic seabird. Journal of Experimental Zoology 255, 141–154.
Jackson, S., Place, A. R. & Seiderer, L. J. (1992). Chitin digestion and assimilation by seabirds. Auk 109, 758–770.
Karasov, W. H. & Levey, D. J. (1990). Digestive system trade-offs and adaptations of frugivorous Passerine birds. Physiological Zoology 63, 1248–1270.
Kostuch, T. E. & Duke, G. E. (1975). Gastric motility in Great-Horned owls. Comparative Biochemistry and Physiology 51, 201–205.
Levey, D. J. & Duke, G. E. (1992). How do frugivores process fruit? Gastrointestinal transit and glucose absorption in Cedar waxwings (Bombycilla cedorum). Auk 109, 722–730.
Levey, D. J. & Karasov, W. H. (1992). Digestive modulation in a seasonal frugivore, the American robin (Turdus migratorius). American Journal of Physiology 262, G711–G718.
Mclelland, J. (1979). Digestive system. In Form and Function in Birds, pp. 69–181. [King, A. S. and McLelland, J., editors]. London: Academic Press.
Martinez Del Rio, C. (1990 a). Sugar preferences in hummingbirds: The influence of subtle chemical differences on food choice. Condor 92, 1022–1030.
Martinez Del Rio, C. (1990 b). Dietary, phylogenetic, and ecological correlates of intestinal sucrase and maltase activity in birds. Physiological Zoology 63, 987–1011.
Place, A. R. & Stiles, E. W. (1992). Living off the wax of the land: Bayberries and Yellow-rumped warblers. Auk 109, 334–345.
Swart, D., Mackie, R. I. & Hayes, J. P. (1993). Influence of live mass, rate of passage and site of digestion on energy metabolism and fibre digestion in the Ostrich (Struthio camelus). South African Journal of Animal Science 23, 119–124.
Walsberg, G. E. & Thompson, C. W. (1990). Annual changes in gizzard size and function in the frugivorous bird. Condor 92, 794–795.