OrnoTest3 - Avian Digestion • Birds spend most of their...

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Unformatted text preview: Avian Digestion • Birds spend most of their time while they’re awake doing energetically demanding tasks o Preserving their lives and their genes all the time • Birds have a high metabolic rate o Require very rapid and efficient digestion of food • Digestive system in a bird is similar to that in reptiles and mammals • Digestive system undergoes specialization to fit the needs of each different bird o Digestive tracts are Adapted depending on their diet Can be seen throughout the digestive tract Dabbling ducks go from being herbivores to carnivores during mating season to meet their protein requirements for making egg shells • The Beak o The shape and size of the beak reflect the relationship between the food that the species takes in and the handling time that the bird has to input in order to get it to a form that it can consume o Main functions Exposing the food (woodpecker tearing bark from tree) If it’s a predatory type, the food may have to be seized and killed and prepared for swallowing o Specializations of the beak Steppe Eagle – sharp hooked beak that helps take apart the animal White-throated Sparrow and Northern Cardinal – seed eaters • Nibbling, crushing, almost a forceps type of beak Shorebirds – long, delicate probing beak • Used to probe down into the substrate and find invertebrates hidden in the mud around the edge of a pond Woodpecker – heavy, blunt, chisel/pick type of beak Northern Shoveler – broad, water strainer o Beak has been adapted and readapted many times over during evolution, but it is still one of the most plastic components of the digestive system o In birds of prey or gallinaceous birds, the beak demonstrates a lot of uniformity Pretty similar in basic shape and structure o In other birds like larks and ground finches, the beak is a highly variable structure in terms of its basic shape and size o Peter and Rosemary Grant Studied birds from the Galapagos Found out that the selection factors on the Galapagos islands are very extreme • In one bad year where it is dry, you’ll see a dramatic increase in the frequencies of a bird depending on its diet • Bucal (mouth) Cavity o Upper part of the cavity is the hard palate that separates the food and nasal palate o The floor is a membranous palate In some species, it can be used as a pouch to store food, like in pelicans o Salivary glands present in the pharynx Pharynx is the part of the digestive tract form the back of the mouth to the esophagus • From the underside of the skull to the 6 th cervical vertebra • Has a number of mucous glands in the softer parts of the mouth o Responsible for moistening and lubricating the food In seedeaters, the salivary glands are numerous and they also secrete a starch-digesting enzyme along with their fluids Swifts use their dry saliva to cement their nest to a surface • Edible Swiftlet – builds its entire nest out of saliva o Chinese use their nests to make birds’ nest soup...
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This note was uploaded on 09/19/2011 for the course 1 101 taught by Professor Larrydavid during the Spring '11 term at South Carolina.

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OrnoTest3 - Avian Digestion • Birds spend most of their...

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