Postmortem animal scavenging of forensic interest

Abstract

Human remains of forensic interest are often scavenged by animals in South Africa. Scavenger modifications of bones could be misinterpreted as tool marks or evidence of trauma caused by a weapon, i.e. sharp, blunt and projectile traumas. Understanding the species-specific and region-specific scattering patterns and behaviours of local scavenger guilds could assist in the holistic collection and forensic analysis of scattered remains. This study aimed to identify scavenging animals of forensic interest in South Africa and describe their scavenging behaviours, scattering patterns, and scavenging induced bone modification patterns. Sparsely fleshed articulated bovine front and hind limbs, and ribs were fed to wild dog, spotted hyena, lion, leopard, black-backed jackal, caracal, and Cape porcupine at the National Zoological Gardens of South Africa. The surviving skeletal elements were collected after two days and their scavenging induced bone modifactions were described. Thirty two pig carcasses (Sus scrofa domesticus) (40-80 kg) were also deployed in winter and summer periods in four different environments: a rural wildlife facility (Wits Rural Facility); an abandoned building complex in Braamfontein, Johannesburg; an urban veld (Frankenwald); and a peri-urban agricultural farm (Miertjie Le Roux Experimental Farm). Motion activated cameras recorded the animal scavenging activities. The scavenger species were identified and their behaviours were described. The scattering patterns were mapped and compared and their bone modification patterns on bone were described. Felids, hyena, porcupine, and mongooses leave potentially distinct identifying bone modification patterns. Vultures (hooded, white-backed, and lappet-faced) dominated the rural scavenging guild, which included marabou stork, slender and banded mongoose, genet, civet, warthog and honey badger. Vultures scavenged after 18-28 hours, skeletonised carcasses between 5 - 98 minutes, and scattered remains up to 7.09m. Slender mongooses were the only scavengers in the urban veld and scattered remains up to 10.5 meters. In the urban city centre, hadeda ibis scavenged on carrion intestines and created multiple, large holes in the skin and removed the lips to access colonising insects. Black-backed jackals dominated the peri-urban scavenger guild, which included mongooses (slender, yellow, and water mongoose), Cape porcupine, and honey badges. Jackals scattered remains up to 73.7 m. The results of this study will assist forensic investigators to discern non-human animal scavenging patterns, effectively locate scattered remains, and assist in reconstructing postmortem scavenging events in various South African environments