They are full of undigested material and not functioning the way they should,» Wyss - Coray says. (scientificamerican.com)
The relative abundance and damage patterns of the fossils representing small mammals and birds suggest that they are derived from undigested material regurgitated by owls (owl pellets). (science.sciencemag.org)
Temporary bouts of constipation are normally a result of a blockage of some kind, which can include undigested materials such as hair or feathers, or a poor diet. (petpeoplesplace.com)