Defense Date


Document Type


Degree Type

Master of Science

Degree Name

Marine Science

First Advisor

David W. Kerstetter, Ph.D.

Second Advisor

Lynn Miller, Ph.D.

Third Advisor

Bernhard Riegl, Ph.D.


Ciconiiformes, Pelicaniformes, Ardeidae, caeca, avian gastrointestinal tract


Situated on the lower digestive tract, caeca typically project cranially from the juncture of the small and large intestine. Recent studies have proposed that the role of caeca in the avian system is to act as fermentation chambers to synthesize vitamins, modulate gut microflora, and absorb nutrients; however, functionality differs with diet. Caeca are a typical characteristic of the avian gastrointestinal tract, with varying sizes and shapes, or even rudimentary or absent in some species. Caeca are notably singular and relatively small in Ardeids. Morphometric consistency in the number and presence of caeca on the lower intestinal tract of Ardeids was determined on a sample of 70 birds obtained from South Florida wildlife rehabilitation centers. This study also reports the findings of caeca length relative to morphometric and intestinal measurements. Caecum length relative to tarsus length was found to be significantly different between Cattle Egrets and Green Herons along with Green Herons and Great White Herons. Caecum length relative to small intestine length was significantly different between Great Egrets and Cattle Egrets. In order to further the understanding of Ardeid caeca, next steps include further research into the function of caeca in piscivorous birds and an in-depth look at the bacteria found in the avian caecum. In particular, future studies can be aimed at understanding why Green Herons differ so greatly from other Ardeids.