Preservation of bird bones: erosion versus digestion by owls

Surface damage to bird bones from pellets of three species of owls ( S. aluco , A. otus and B. bubo ) was compared with that of bird bones exposed to weathering and soil corrosion (Záskogo Cave in the Western Balkan Mountains, Bulgaria and Ciemna Cave, southern Poland). Scanning electron microscopy and light microscope examinations indicate that the effects of weathering of bird bones (extensive pitting and flaking away on whole bones, holes with sharp edges, depressions with rough bottoms and sharp edges of breakage) are distinguishable from those of digestion (rounding of hole edges on articular ends and sometimes on shafts, rounding of breakage). However, soil corrosion may produce similar rounding to that of digestion, which may hamper taphonomic interpretations of fossil assemblages. Two stages of weathering in bird bone are distinguished. Generally, the kind of damage done to bird bones is similar to that done to mammalian remains. Taphonomic studies of fossil bird remains should take into account a combination of features, including surface damage, fragmentation and possible chemical alterations of bone tissues. © 1997 John Wiley & Sons, Ltd.