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

Which components of diet quality affect retention time of digesta in seabirds?

“…The most plausible reason is that the in vitro digestion technique fails to mimic gastric digestion accurately, and thereby underestimates digestion rates of Sprat, relative to Whiting. Although the samples were agitated, they were not squeezed as would happen in a seabird’s stomach due to muscular contractions (Duke 1989; Duke, Place & Jones 1989; Stevens & Hume 1995). Personal observation suggests that Sprat is the more physically fragile of the two species.…”

Variation in Chick Provisioning of Streaked Shearwaters (Calonectris leucomelas) during the Early Nstling Stage

“…(McLelland 1979). For example, the proventriculus of a Great Horned Owl (Bubo virginianus) is about half the size of the gizzard, whereas its size in a Leach's Storm-Petrel (Oceanodroma leuchorhoa) is about 20 times larger than the size of the gizzard (Duke et al 1989). This indicates that the food containing capacity of both adults and chicks are important in the provisioning pattern of Procellariiformes, because they have a relatively long feeding interval compared with those of land birds.…”

Nutrient composition of the crop contents of growing and adult grey‐faced petrels (Pterodroma macroptera):A preliminary investigation

“…The calcium to phosphorus ratio was similar in both samples and consistent with ratios normally found in diets of other growing avian species such as chickens, turkey, quail and geese (National Research Council 1994) Especially notable are the high manganese and selenium levels The manganese levels should not be considered toxic, as other birds can tolerate levels of > 1000 mg/kg diet (National Research Council 1994), but the selenium levels recorded here would be toxic to other birds Animal tissues generally contain higher levels of selenium than plant material (Levander & Burk 1996) and it is possible that grey faced petrels, as an evolutionally adaptation, can tolerate especially high levels of selenium Petrels have been noted for their ability to concentrate dietary oil in their stomach (Warham 1996) This "stomach oil", once believed to be excreted by the crop of the birds (Lewis 1966), originates from dietary lipids, and the anatomical structure and motility of the digestive tract plays a major role in formulating it (Duke et al 1989, Roby et al 1989 The amount of stomach oil in chicks of some if not most, petrel species declines as they approach fledging age (Warham 1996) Very young chicks (<5 d) are usually fed by the adult which has been in the burrow with them for 3-7 days around hatching The first food they receive tends to be rich in oil and paste and poor in big chunks of fresh food Thereafter, as the chicks get bigger, large pieces of food plus paste and oil are delivered to them by the adults Our results therefore need to be interpreted with some caution Except for higher levels of certain ammo acids in the crop content of the 3-5 d old birds, there was a high degree of uniformity in the ammo acid composition of the crude protein fraction across the other age groups The ammo acid composition of the crop content samples was consistent with that of the ammo acid composition of squid, krill and fish (Suzuki 1981) However, the taunne levels increased with the age of the chicks, and may be a result of seasonal changes in the diet of the adults Young chicks are present on land only in September, and the food eaten by the adults (and then delivered to the chicks) may have contained less taunne during this time…”