Bear feeding on carrion – impact of severe damage on decomposition rate and insect succession on carcasses – a case study

Knowledge of when insects appear on a carcass and the duration of their presence plays an important role in estimating the post-mortem interval (PMI). Each necrophilous species has different feeding habits and reproductive strategies which determine when it appears on a carcass. However, their presence can be influenced by a number of factors, including extensive post-mortem damage resulting from feeding by scavengers. The present study focuses on the role of invertebrates in the decomposition of a carcass situated in Zakopane, which borders directly on the Tatra National Park. Thus the aim of the study was to assess the impact of post-mortem damage on the species composition of insects on the carcass of a domestic pig (Sus scrofa domesticus L.). Analysis of the changes in insect populations and in the time of individual decomposition processes revealed that such extensive damage affects the decomposition of the carcass, when insects appear on it, and how long they remain, which is important information in forensic entomology. Most of the insect species were shown to appear earlier on the damaged carcass and were present on it for a significantly shorter time.
Of the 24 species of minimum abundance (N ≥ 4), 14 species appeared at least 24 h earlier on the damaged carcass, while four were observed earlier on the control carcass. The study demonstrates the need to take into account factors such as scavenging by predatory vertebrates in determining post-mortem interval on the basis of decomposition changes and on the basis of insect succession.