Gastric Emptying and Gastrointestinal Motility in Leach's Storm-Petrel Chicks (Oceanodroma leuchorhoa)

We used radiographic techniques to observe gastric motility during digestion of a meal in four Leach's Storm-Petrel chicks, 40-55 days old. A radio-opaque substance was added to the daily feeding for radiographic observation. We observed a biphasic gizzard contraction cycle with a frequency of 7.5 cycles/min. Gastric emptying occurred with each cycle and frequent intestinal refluxes were observed. Proventricular contractions were rarely observed; when observed, they affected only the ventral surface near the gizzard. Layering of proventricular contents, which we assumed to be a layer of dietary lipid over an aqueous phase, developed postprandially. Limited proventricular motility would favor layering; and ventral proventricular motility, along with regular gizzard motility, would promote gastric emptying of the more ventral aqueous layer. These observations are consistent with the idea that procellariiform "stomach oils" are of dietary origin and that lipid accumulation in the stomach is linked to a unique gastrointestinal anatomy and motility.