Scavenger Species-typical Alteration to Bone: Using Bite Mark Dimensions to Identify Scavengers

Comparison of the effectiveness and efficiency of the grid and link search methods to recover scattered skeletal remains

The grid and link search methods are used to recover scattered skeletal remains. Neither have not been compared robustly and clear guidelines for the link method have not been sufficiently developed. The study aimed to compare the effectiveness and efficiency of both methods and propose guidelines for the link method. The scattering patterns of two scavengers of forensic relevance-slender mongooses (Galerella sanguinea) and black-backed jackals (Canis mesomelas)-were recreated using four pig skeletons (Sus scrofa domesticus). Two groups (n = 6 each) were assigned a different method to recover the scattered remains. The length of the search and when each bone was located for each scatter pattern was recorded for each group and scatter pattern. A Likert scale questionnaire assessed participants' perceptions of their assigned method. A paired t-test (p = 0.005) compared the efficiency of each method and the questionnaire answers. Both methods were effective, recovering 100% of all remains. The link method was more efficient for both scatter patterns, despite there being no statistical significance (jackal: p = 0.089; mongoose: p = 0.464). Participants indicated favorable views for both methods; however, the link method scored significantly more favorably (p = 0.01) for efficiency. Specific guidelines were developed for the use of the link method. The link method is suggested for the recovery of scattered remains in forensic contexts, especially when the scavenger, its behavior, and scattering pattern is known or suspected.

Taphonomic signatures of early scavenging by black and turkey vultures

Scavenging is critical for nutrient cycling and maintenance of healthy ecosystems. While there is substantial research into the identification of taphonomic signatures from facultative mammalian scavengers, early stage scavenging signatures by vultures remain unknown. Further, some vulture species are opportunistic predators, highlighting the need to define signatures observed in the course of normal scavenging behavior. We placed stillborn neonatal calves in an unoccupied pasture and used motion-trigger camera traps to quantify scavenging effort, then conducted necropsies to evaluate the effect of black vulture (Coragyps atratus) and turkey vulture (Cathartes aura) scavenging effort on carcass consumption. We measured the order of consumption of different tissue types to delineate which anatomic structures vultures consume first. Scavenging trials with higher numbers of vultures feeding on the carcass for longer were associated with decreased remaining tongue and abdominal viscera, and a larger umbilical wound. Greater maximum flock sizes were associated with decreased remaining tongue and abdominal viscera, a larger umbilical wound, and greater biomass consumption. Black vultures targeted the perineum and tongue earlier, while turkey vultures targeted the eyes, perineum, and tongue. These results are consistent with the idea that vultures prefer tissues that are easy to access and contain high nutrient content. These patterns form a distinctive taphonomic signature that can be used to identify early scavenging by black and turkey vultures. Our results demonstrate that criteria commonly used to identify livestock depredation by black vultures only document vulture presence and not predation. This distinction implies that new and more definitive criteria need to be developed and put into practice for more accurate decision criteria in livestock depredation compensation programs.

Post-Mortem Dental Profile as a Powerful Tool in Animal Forensic Investigations—A Review

Veterinary forensics is becoming more important in our society as a result of the growing demand for investigations related to crimes against animals or investigations of criminal deaths caused by animals. A veterinarian may participate as an expert witness or may be required to give forensic assistance, by providing knowledge of the specialty to establish a complete picture of the involvement of an animal and allowing the Courts to reach a verdict. By applying diverse dental profiling techniques, not only can species, sex, age-at-death, and body size of an animal be estimated, but also data about their geographical origin (provenance) and the post-mortem interval. This review concentrates on the dental techniques that use the characteristics of teeth as a means of identification of freshly deceased and skeletonised animals. Furthermore, this highlights the information that can be extracted about the animal from the post-mortem dental profile.

Identifying forensically relevant urban scavengers in Johannesburg, South Africa

Unidentified human remains are frequently recovered in urban environments in South Africa, which undergo forensic (medico-legal) investigations. These remains often exhibit animal scavenging modifications and are frequently scattered by animals. This impacts the collection and forensic analysis of the remains. This study aimed to identify scavenging animals present in two urban environments in Johannesburg, South Africa, and describe their scavenging and scattering behaviours. Six pig carcasses (Sus scrofa domesticus) (30-80 kg) were placed in a veldt in Johannesburg and in an abandoned building complex. Motion-activated cameras recorded the scavenging activities. Scavenger species were identified and their behaviours, scattering pattern, and scavenging bone modifications were described. Slender mongooses (Galerella sanguinea) were the most prolific veldt scavengers. They scattered remains to a maximum distance of 10.5 m in two directions: north and southeast. These mongooses scavenged during the advanced and dry decomposition stages. Gnawing on the angle of the mandible - with multiple parallel scores on the flat surfaces and the angle margin having a stepped appearance - may be a distinguishing scavenging modification feature of the slender mongoose. Hadeda ibis (Bostrychia hagedash) were the only scavengers recorded scavenging on the intestines of a pig carcass in the abandoned building complex. They favoured colonizing insects and created multiple, large holes in the skin and removed the lips to access the insects. The described scavenging behaviours will assist in the reconstruction of postmortem events in forensic cases and the location and collection of scattered remains in Southern Africa.

Uncovering Forensic Taphonomic Agents: Animal Scavenging in the European Context

Simple Summary

In forensic cases of exposed human bodies, vertebrate animals frequently pose challenges concerning remains recovery, identification, and the interpretation of circumstances of death. For instance, they can remove body parts, destroy skeletal features, and create “pseudo-lesions” that complicate trauma analysis. With this review, we highlight vertebrate scavengers in Europe that are of forensic relevance, including their typical behaviour and their inflicted lesions on bones and soft tissues. Here, we support forensic practitioners in recognising animal activity at the site of discovery and in interpreting the circumstances of death. Our review serves as a guide for the examination of animal-altered human remains and their found state by providing ecological backgrounds on various vertebrate species. In addition, this study provides an overview of the current state of research in the field of animal scavenging in forensics.

Abstract

Animal scavenging by vertebrates can significantly alter human bodies and their deposition site. For instance, vertebrate animals can cause postmortem modification to a body, alter perimortem trauma, influence decomposition rates, disarticulate and scatter body parts or evidence, and affect the identification of the deceased. Animal scavenging is a relatively common occurrence in forensic investigations. Even so, studies on the subject are scattered and rare, with most focussing on geographical areas outside of Europe. For that reason, we intend to collate the literature to provide an account of forensically relevant vertebrate scavengers in Europe, their impacts on human remains, and their implications for forensic investigations. Here, we provide an overview of forensic aspects where the knowledge of animal scavenging is crucial, as well as an account of potential scavengers of human remains in Europe and their typical alterations to soft tissue and, in particular, to bones. In addition, we are the first to provide a guide for forensic practitioners to identify the presence of vertebrate scavenging and subsequently inform outdoor search strategies for affected human remains.

Multi-agent scavenging patterns in Hawai'i: A forensic archaeological and skeletal case study

Knowledge of the behavior of local fauna can aid forensic investigators in developing awareness of site formation processes. In Hawai'i, little has been published on the effects of feral domestic pig (Sus scrofa) and feral domestic dog (Canis familiaris) scavenging and bone dispersal on field recovery and laboratory observations. In this Pacific tropical setting, the most consequential terrestrial taphonomic agents are pigs and dogs, both in terms of hard tissue modification and dispersal of remains across the landscape. In 2017, an archaeologist discovered the remains of an unidentified decedent on the island of Kaua'i, State of Hawai'i during a cultural resource management survey. Subsequently, a forensic recovery team in conjunction with Kaua'i police and crime scene investigators used archaeological techniques, including pedestrian survey, tape-and-compass, and GPS mapping, to map and recover the remains. A feral pig trail transected various areas of the recovery site and corresponded with the distribution pattern of recovered skeletal material, including both the main concentration more broadly dispersed skeletal elements. While much of the skeleton was present, missing or unrecovered skeletal elements are consistent with expectations based on existing literature. Much of the postmortem bone deformations were characteristic of marks related to feral dog and/or feral pig scavenging. These results assisted local investigators in deciding the manner of death, as well as providing the family with an accounting of the decedent's remains for burial. Thus, forensic anthropologists and archaeologists need to understand and develop knowledge of local animal behavior to recover and interpret human remains of medicolegal significance.

Taphonomic information from the modern vertebrate death assemblage of Doñana National Park, Spain

Modern death assemblages provide insights about the early stages of fossilization and useful ecological information about the species inhabiting the ecosystem. We present the results of taphonomic monitoring of modern vertebrate carcasses and bones from Doñana National Park, a Mediterranean coastal ecosystem in Andalusia, Spain. Ten different habitats were surveyed. Half of them occur in active depositional environments (marshland, lake margin, river margin, beach and dunes). Most of the skeletal remains belong to land mammals larger than 5 kg in body weight (mainly wild and feral ungulates). Overall, the Doñana bone assemblage shows good preservation with little damage to the bones, partly as a consequence of the low predator pressure on large vertebrates. Assemblages from active depositional habitats differ significantly from other habitats in terms of the higher incidence of breakage and chewing marks on bones in the latter, which result from scavenging, mainly by wild boar and red fox. The lake-margin and river-margin death assemblages have high concentrations of well preserved bones that are undergoing burial and offer the greatest potential to produce fossil assemblages. The spatial distribution of species in the Doñana death assemblage generally reflects the preferred habitats of the species in life. Meadows seem to be a preferred winter habitat for male deer, given the high number of shed antlers recorded there. This study is further proof that taphonomy can provide powerful insights to better understand the ecology of modern species and to infer past and future scenarios for the fossil record.

Forensic cases of suspected dog and cat abuse in the Community of Madrid (Spain), 2014-2019

Companion animal abuse is an issue that concerns not only veterinarians and law enforcement agencies but also society in general. Animals that die under suspicious or violent circumstances should be submitted to reference laboratories for a postmortem examination by veterinary forensic pathologists trained to recognize animal abuse. Nevertheless, the low notification rate of such cases in Spain may explain the country's lag in the development of veterinary forensics and the limited information available on animal abuse epidemiology in comparison with other countries. By sharing information among the entities involved in recognizing animal abuse, we can better address these issues, thus improving veterinary forensics in Spain (and elsewhere). In this study, we analysed the cause and manner of death of 96 dog and cat carcasses suspected of animal abuse. These cases were submitted to our diagnostic laboratory for forensic postmortem examination by public agencies and animal protection centres. To our knowledge, this is the first study to focus on the postmortem analysis of forensic cases of suspected dog and cat abuse in Spain. On the basis of gross and histopathological findings, we distinguished between natural and non-natural abuse-related deaths, classifying the latter. We confirmed that most of the dog deaths were related with abuse, though the suspected abuse and the cause of death did not always coincide. In contrast, cause of death was determined to be natural in many of the cat suspected abuse cases. The most frequent non-natural abuse-related cause of death in dogs was blunt force trauma (n=24, 43.64%), followed by firearm injuries (n=10, 18.18%), asphyxia (n=5, 9.09%), heatstroke (n=3, 5.45%), starvation (n=2, 3.64%), bite injury (n=1, 1.82%), and sharp force trauma (n=1, 1.82%). In cats, the most common cause of death was blunt force trauma (n=9, 21.95%), followed by firearm injuries (n=3, 7.32%) and bite injury (n=2, 4.88%). The main goal of our study is to share our results with the scientific community to advance the field of veterinary forensics in Spain, which will lead to more successful prosecutions by law enforcement agencies. Finally, we highlight that veterinarians who can accurately recognize signs of animal abuse may be able to better respond to cases of companion animal cruelty, which in turn, may prevent possible escalation to interpersonal violence.

Scavenger activity in a peri-urban agricultural setting in the Highveld of South Africa

Scavenging animals often scatter skeletal remains of forensic interest and cause scavenging damage. This study aimed to identify scavenging animals in the peri-urban agricultural Highveld of South Africa, describe their scattering patterns, and the damage they cause to bone. Ten pig carcasses (Sus scrofa domesticus) (40-80 kg) were placed at the University of Pretoria's Mierjie Le Roux Experimental Farm (Highveld) in summer and winter. Motion-activated cameras recorded the scavenging. Scavenger species were identified and their behaviors, scattering pattern, and the damage they cause to bone were described. Scavenging was primarily by black-backed jackals; however, mongooses (slender, yellow, and water mongoose), Cape porcupine, and honey badger were also active. Remains were commonly scattered in two directions by jackals. The distance of scattering was heavily influenced by fencing. The remains were scattered within a maximum radius of 73.7 m. The remains were scavenged and skeletonized faster in summer. Jackals caused minimal damage to bone, isolated to superficial, nonspecific scores, furrows, and punctures. A few mongoose bone alterations were present as jagged gnaw marks on the angle of the mandible and gnawing of the vertebral spinous process. Cape porcupine bone damage included gnaw marks on the condyle of a femur and head of humerus, and destruction of the proximal and distal ends of a tibia. The described scattering pattern and bone modification patterns will assist in the recovery and analysis of scavenged remains found in peri-urban agricultural areas in South Africa.

Taphonomic bone trauma caused by Southern African scavengers

Forensic anthropologists in Southern Africa are often confronted with post-mortem modifications of human skeletal remains caused by animal scavenging. This is troublesome as the post-mortem pseudo-trauma could be misinterpreted. This study aimed to describe the skeletal trauma caused by Southern African scavengers which are of forensic interest. The scavenging animals selected for this study included wild dog, spotted hyena, lion, leopard, black-backed jackal, caracal, and porcupine housed at the National Zoological Gardens of South Africa. Sparsely fleshed and articulated bovine front and hind limbs as well as ribs were placed in each animal enclosure and collected after 2 days for cleaning and analysis. Felids (lion, leopard, and caracal) gnawed away the greater trochanter of the humerus leaving deep, parallel furrows. Hyena caused massive trauma to bone with one-third of the tibia shaft surviving with jagged fracture edges. Porcupines left distinctive fan-like parallel scores and large, oval depressions with an eroded, polished appearance. Wild dogs and jackals did not leave any distinctive patterns. Light scavenging trauma is distinct from other bone taphonomy but cannot be used to determine the species. Heavy scavenging trauma patterns can be used to determine the general type of perpetrating animal; however, the exact taxa or species cannot be determined.

Who is the killer? Barking up the wrong tree

In recent years, several cases of predation on hunting dogs have been reported in Italy. These cases caused uproar among owners and the wolf was singled out as the culprit. The remains of a dog allegedly killed by wolves were submitted for forensic analysis. Wolf predation was ruled out based on gross findings and wild boar aggression was suspected instead. Genetic analysis of salivary swab samples confirmed that wild boars fed on the dog. As poaching is one of the main threats to wolf conservation, it is essential to identify correctly the predator in cases of attacks on domestic animals.