*WINNER* The Impact of a Large Surface Rock on Temperature and Decay Rate


  • Salem Sullivan
  • David Beck
  • Lauren Michel


Do cadavers on rocks decay more quickly? How do rocks affect insect succession and ground level temperature? Is this effect more dramatic on small or large carcasses?

Assuming an organism is not consumed by scavengers, it goes through five stages in the process of decay– fresh, bloat, active decay, advanced decay, and putrid dry remains– which are distinguished through physical observation. Larger masses decay at slower rates, and hotter temperatures tend to expedite decay.

Four rabbit carcasses were placed out to decay. One small carcass and one large carcass were placed out in the sun on soil or on exposed rock. The mass, carcass dimensions, and ground level temperatures were monitored. This experiment was repeated three times over the summer. Insects were captured by hand and pitfall traps.
In the fall and winter, temperature probes were placed at varying heights and lengths from a rocky surface and a non-rocky surface. Temperature was recorded every half hour from September to January.

The effect of the rock on decay rate varied, so this experiment would need to be repeated. Ground level temperatures tended to be higher at the rock sites, and insect colonization was more abundant at the rock sites. Temperature changed more as height from the rock increased compared to length. The difference in temperature between rock and soil site was minimized when ground level temperatures reached 20C, as well as when it rained.

Cadavers next to rocks may decay more quickly in summer months.