Decomposition and the Freeze-Thaw Process in Northwestern Montana: A Preliminary Study

by Wagster, Laura Beth

The goal of this project is to observe decomposition rates of four wolf carcasses over the duration of winter in northwestern Montana and to consider these rates as they apply to humans. Four wolf carcasses were studied in order to assess decomposition rates, particularly winter intervals of the freeze-thaw process and the possibility of the reemergence of insects during ideal conditions. It is hypothesized that the majority of insect activity on the carcasses will be limited to only internal activity during harsh weather conditions. Both carcasses placed in June decayed at predictable rates of decompositional stages and wolves 1 and 2 remained in the dry stage of decomposition in May. Wolves 3 and 4 were placed in September. Wolf 4 decayed at predictable rates of decompositional stages, yet wolf 3 took much longer to transition from the active decay stage to the dry stage. Both carcasses remained in the dry stage of decomposition until May. Continual fluctuations of weather during the winter months at the Lubrecht Forest provided useful information regarding the freeze-thaw process and the presence of insects during conditions otherwise thought to be inhospitable to thier activity. Larvae were observed on all carcasses, even after periods of snow fall and snow melt. After numerous freeze-thaw cycles, wolf 3 was still observed to linger in the advanced stage of decomposition. If applicable to humans, these results provide very useful information regarding what might occur during the decomposition process in an environment such as northwestern Montana. Although the classifications of insects in this study are basic, the proof that they exist and, in fact, re-emerge during winter conditions is significant in itself. The interpretation of this data as it applies to forensic cases offers forensic anthropology a new aspect of the time since death interval.