A Comparison of Bird Digestive Systems by Diet
Loading...
Date
2017-12
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
The Ohio State University
Abstract
The vertebrate digestive system can be modified to accommodate a diversity of diets. In general, herbivores tend to have longer, more complex digestive systems while carnivores have smaller, less elaborate digestive systems, but most of the research in this area examines mammalian morphology. Accordingly, the goal of this study was to determine the influence of diet on digestive system morphology in birds. I expected the size of the intestines, cecum (if present), proventriculus, and gizzard to be larger in herbivorous birds and smaller in carnivorous birds. Birds of varying diets were dissected and their digestive systems (intestines, cecum, proventriculus, and gizzard) were weighed. Additionally, each organ’s percent contribution to total body weight was calculated. Diet was determined by literature and by the gizzard contents of each bird. A mixed model was used for comparisons with the percentage of body mass due to organ weight as the dependent variable, bird diet as a fixed effect, and family as a random effect. Results from 34 birds revealed that diet affected size of the proventriculus but not the size of the intestines, gizzard, cecum, or the total digestive system. The proventriculus size was largest in insectivores and smallest in herbivores, with omnivores having an intermediately-sized proventriculus. Contrary to previous studies, our study did not support the hypothesis that herbivorous diets lead to a larger, more elaborate digestive system than carnivorous diets in birds. Previous studies either focused on one specific species or examined a much wider variety of species. Because some feeding strategies in our study were limited to only a single taxon, our ability to differentiate between taxonomical differences and trophic differences was hindered.
Description
Keywords
Bird, Digestive, Morphology, Diet, Size, Variability