Decomposition ecology of great horned owl (Bubo virginianus) pellets

Background/Question/Methods

Indigestible material is regurgitated in about 320 species of birds in 67 families, and birds of prey regularly regurgitate mucous-covered pellets with bone, fur, feather, chitin and scale remains of prey.  The objective of this study was to investigate the ecology of the decomposition of Great Horned Owl pellets.  Pellets from laboratory Great Horned Owls fed on rats (Rattus norvegicus) were dried, placed in plastic mesh bags, and frozen until 180 pellets had been obtained.  All were then set out in maple-oak hardwoods and in spruce forest sites in July in central New York.  Six pellets were then collected every eight days from each site for four months.  Observed fungi were cultured individually and invertebrates were extracted using modified Tullgren funnels. 

Results/Conclusions

Fourteen species of fungi were isolated, and 7,502 invertebrates occurred on 150 pellets.  145 invertebrate species occurred on pellets in the hardwoods site; 128 invertebrate species occurred on pellets in the spruce site.  Pellet decomposition involves three fungal successional stages – sugar fungi, keratinophilic fungi, and keratinolytic fungi, and three invertebrate successional stages – fresh, dry, and bones.