Effects of soil shrink-swell on bird bones: An experimental taphonomy pilot study

Abstract

The soil burial context of a bird bone assemblage is affected by many different taphonomic factors. In this pilot study, we examined the potential effects of soil shrink-swell on white-tailed dove (Zenaida asiatica) bones experimentally buried in three soils of different clay contents. We predicted that bones buried in high clay soils would experience the most damage from soil shrink-swell. Dove wing and leg bones were buried and exposed to 60 days and eight episodes of cyclic soil shrink-swell. We recovered all bones (humeri, ulnae, radii, femora, and tibiotarsi) and found 77.1% of them to exhibit damage. Significant damage occurred among the humeri, ulnae, radii, and femora buried in high clay soil, supporting our prediction. Each bone experienced at least one of the 10 fracture types we recorded. We found the greatest damage in humeri, for which all experienced damage from pitting. The humeri sample also displayed eight fracture types across bone portions and landmarks. Our pilot study is exploratory and meant to provide information useful for further experimentation with additional bird bones using whole carcasses and excised specimens placed in additional positions and soil conditions.