Animal Scavenging Research Articles

Felid scavenging in forensic taphonomic research: An experimental approach

Animal scavenging on human remains presents a major challenge at a forensic scene. These lasting changes can influence the interpretation of a post-mortem interval, the overall state of the remains and any associated evidence, impacting the integrity of the scene. Therefore, identifying taphonomic related changes due to animal scavenging is important to understand the post-deposition sequence of events. However, knowing where to look is challenging and animal scavenging studies are difficult to create. Therefore, this study worked in collaboration with zoological institutes in the UK to capture the scavenging changes to horse bone, focussing on the locations of scavenging on bone and the characteristics left. This study focused on large felid (cheetah, lion, tiger, leopard) scavenging, which is less documented in comparison to canine scavenging. This research demonstrated the distribution patterns of tooth activity associated with large felid scavenging is consistent with those reported in the taphonomic literature on lions. Specifically, pits, punctures, scalloping and furrowing were found and characteristics were frequently noted at the borders and flat regions of bones. This study adds to the forensic discussion of scavenging. While focussing on large cats, the work demonstrates anatomical regions that may be affected by scavenging and the visual cues that may help identify animal interaction over human.

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 SummaryIn 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.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.

Animal Scavenging as Social Metaphor: A Carved Chlorite Vessel of the Halil Rud Civilization, Kerman, Iran, Mid Third Millenniumbc

A fragmentary large chlorite vessel of the Halil Rud valley civilization (Kerman, Iran, mid third millenniumbc), found in unknown circumstances and recently recovered by the police forces of Iran, is discussed in the wider scenario of coeval animal iconographies of middle and southwest Asia. Beginning from the imagery carved in the two superimposed friezes of the reassembled fragments, we review the different theoretical approaches in interpretation of similar animal iconography. The figuration of the vessel is interpreted as a scene of the scavenging of bovine carcasses by three different animal actors: lions and birds of prey/vultures, but also hyenas—a subject previously unknown in the art of the reference regions. Following a review of the interrelations of these species in scavenging and with humans, particularly in the coeval context of domestic animal exploitation and developing urban settlement, we investigate the potential semantic implications of the iconography in terms of the symbolism and ideology in the social context.

Animal scavenging on pig cadavers in the Lowveld of South Africa

Scavenging animals often scatter skeletal remains of forensic interest and leave bite marks. This study aimed to identify scavenging animals in the rural Lowveld of South Africa and to describe their scattering pattern and bite marks on bone. Ten pig cadavers (Sus scrofa domesticus) (40–80 kg) were placed at the Wits Rural Facility, Limpopo, South Africa during the summer and winter seasons. Motion activated cameras recorded the scavenging. Scavenger species were identified and their behaviors, scattering pattern, and bite marks were described. Scavenging was primarily by vultures (hooded, white-backed, and lappet-faced). Marabou stork, slender and banded mongoose, genet, civet, warthog and honey badger also actively scavenged. Vultures began to scavenge the pig cadavers after 18hrs in summer and between 26 and 28 h in winter and skeletonized pig cadavers rapidly between 5 and 98 min. Skeletonization occurred more rapidly and diffusely in summer while winter cases were densely scattered. Overall the scattered remains were within an area of 157.9 m2/1705.5 ft2 with a radius of 7.09 m/23.3 ft. Vultures cleaned bones thoroughly with very minimal markings - primarily nonspecific scores. The described scattering pattern and bite marks will assist in the recovery and analysis of scavenged remains.

A preliminary investigation into the decomposition rate of wild boar carcasses in forest habitats

The estimation of the postmortem interval (PMI, the time that has elapsed since the death) is a critical issue for the biosecurity enforcement officers who implement to the timely establishment of biosecurity zone for preventing susceptible animals from disease transmission given the rapid occurrence of an infectious disease. Increasing attention has been paid to PMI of wild boar (Sus scrofa) carcasses associated with African swine fever epidemics in Korea since October 2019 to explain the geographical transmission of the disease, as well as to provide potential target animals for prevention measures in terms of farm biosecurity. This study is, to the best of our knowledge, the first to describe the decomposition process of wild boars in different microhabitats in the country. In the present comparative study, we obtained field data from the decomposition process of the wild boar and domestic pig carcasses continuously exposed aboveground in natural environment settings allowing animal scavenging. This study compared the pattern of decomposition in 16 wild boar carrion and 10 domestic pig carcasses placed between August and November 2019. Quite differences in decomposition rate measured by total body score and tissue's gross morphology over time were observed between wild boars and domestic pigs. Overall, the wild boar decomposed much more slowly than the domestic pig throughout the end of the experimental period. In addition, color changes to the skin were easily seen in domestic pigs, whereas there is much variation in the wild boar, especially carcasses placed in late autumn. Moreover, some wild boar carcasses did not show any sign of bloating. These results indicate that decomposition rates derived from forensic taphonomic studies on domestic pigs may be not directly applicable to the wild boar, hence there is a need to develop regional decomposition models to be employed in different geographical situations to increase the accuracy of PMI of wild boar carcasses.

Postmortem cadaveric depredation by animals– A diagnostic dilemma

Post-mortem animal predation may sometimes confuse at first sight with injuries of crucial origin, thus arousing suspicion of ante-mortem external violence. A reliable differentiation of the origin of such uncertain injuries is of vital importance, a fact that is mainly true for the investigation of suspected homicide and/or man made body mutilation after death. In forensic pathology, the identification of injuries caused by animals as post-mortem artefact is usually done by forensic pathologists with vast practical experience and special knowledge of the appearance and morphology of tooth marks of carnivores and rodents, respectively. Meticulous examination can only help to differentiate the cut in bones by sharp weapons or sawing of long bones by sharp weapons, for surgical amputation, from gnawing of dead bones by wild animals, showing no ante-mortem reaction. Here, we present a case report of a young adult male individual, who was found dead on railway tracks with alleged history of railway accident and all the facial features distorted by animal scavengers resulting in difficulty in identification, injury differentiation & cause and manner of death. Keywords: Artefact, post-mortem, Scavenging, Depredation, Animals, Injuries, Mutilation

Prototype Development of IoT Based Smart Waste Management System for Smart City

The inefficient waste collection system has resulted in environmental pollution and large consumption of sources of energy. This is because of inefficient waste collection systems result in smell pollution, unpleasant views, breading of insects, animal scavengers and rodents which also giving rise to a range of diseases when some waste bins are left overloaded and uncollected. As one of the efforts to overcome the inefficiency of the waste collection system problem and to achieve smart cities, an IoT (Internet of Things) based smart bin prototype is proposed in this paper. Altogether, it is an automatic centralized monitoring system that provides the timely status of a bin, enables optimal route planning for collections, reduces collection times, and saves costs as well as fuel consumption.

Succession of bacterial communities on carrion is independent of vertebrate scavengers.

The decomposition of carrion is carried out by a suite of macro- and micro-organisms who interact with each other in a variety of ecological contexts. The ultimate result of carrion decomposition is the recycling of carbon and nutrients from the carrion back into the ecosystem. Exploring these ecological interactions among animals and microbes is a critical aspect of understanding the nutrient cycling of an ecosystem. Here we investigate the potential impacts that vertebrate scavenging may have on the microbial community of carrion. In this study, we placed seven juvenile domestic cow carcasses in the Grassy Mountain region of Utah, USA and collected tissue samples at periodic intervals. Using high-depth environmental sequencing of the 16S rRNA gene and camera trap data, we documented the microbial community shifts associated with decomposition and with vertebrate scavenger visitation. The remarkable scarcity of animals at our study site enabled us to examine natural carrion decomposition in the near absence of animal scavengers. Our results indicate that the microbial communities of carcasses that experienced large amounts of scavenging activity were not significantly different than those carcasses that observed very little scavenging activity. Rather, the microbial community shifts reflected changes in the stage of decomposition similar to other studies documenting the successional changes of carrion microbial communities. Our study suggests that microbial community succession on carrion follows consistent patterns that are largely unaffected by vertebrate scavenging.

The impact of scavenging: perspective from casework in forensic anthropology

Forensic anthropology casework frequently encounters evidence of animal scavenging associated with fragmentation and loss of skeletal material. Published research demonstrates that patterns of destruction in bone can suggest the size and type of animal involved. This study analyzes 107 cases reported on by the first author at the Smithsonian Institution to investigate patterns of scavenging in forensic anthropology casework. This investigation reveals that the extent of scavenger impact varies across the body, but primarily is concentrated in the central body area. Although extensive animal scavenging can limit analysis, some evidence of foul play can be preserved.

Autopsy as a form of evisceration: Implications for decomposition rate, pattern, and estimation of postmortem interval

Evisceration following penetrating trauma or animal scavenging has the potential to affect the probative value of biological evidence and postmortem interval estimation. Autopsy presents an opportunity for controlled assessment of the rate of decomposition following evisceration. A balanced sample of twenty-six human cadavers was used to assess intergroup rate and trajectory of decomposition at the Forensic Investigation Research Station in Whitewater, Colorado. A linear mixed model using maximum likelihood estimates showed that the decomposition rate did not differ between autopsied and non-autopsied donors based on a comparison of slopes χ2(1)=0.223, p=0.637. The results demonstrate that penetrating trauma and the loss of systemic continuity following evisceration affect the pattern of decomposition, but not the rate. This suggests that the bloat phase may not be a major catalyst of decomposition, and that evisceration may not preclude the use of scopic methods for estimating postmortem interval, when sufficient peripheral tissue is retained.

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 2days 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.

Not all rotten fish stink: Microbial changes in decaying carcasses increase cytotoxicity and potential risks to animal scavengers

Dead animal bodies occur naturally in ecosystems, are regularly washed up along ocean beaches, and are a key component of many coastal food webs where scavenging animals consume carcasses. Microbes that decompose carcasses can, however, produce toxic chemicals during putrefaction. This is frequently assumed to have negative consequences for scavengers in the wild, but has been rarely quantified. In this study, we measured how changes in the microbial assemblages of decaying fish affect the toxicity of carcasses. We did this by allowing fish carcasses to decompose in the field for up to 31 days in the dunes of a sandy beach; an ecosystem where scavenging animals are common. Carcasses were sampled daily and the tissues tested for changes in culturable microbial communities using 100 μL samples of whole carcass homogenates on marine and sheep blood agar, and changes in cytotoxicity using Vero cell assays. Cytotoxicity peaked 11 days after deployment showing 95% rounded and detached cells. Cytotoxicity was lower in the early phases of decay as microbial communities developed and after approximately two weeks when carcasses dried. The peak in toxicity correlated with peaks in the abundance of Acinetobacter, and Vibrio and Alivibrio; microbes known to produce toxins. This trajectory of toxicity suggests an ecological model where microbes may predictably determine the palatability of carrion in food webs, making both fresh and aged carcasses the least risky proposition for scavenging animals. This ‘fresh and aged carcasses are best’ model is highly amenable to testing in the context of carrion-centred food webs in multiple systems, and it has practical applications in conservation where animal carcasses are provided to threatened, and often iconic, scavenger species.

Water monitors; implications in forensic death investigations

Introduction: Outdoor postmortem animal scavenging is frequent and the predators responsible vary from ants, foxes, bluebottles to monitor lizards. Postmortem scavenging by water monitors is not uncommon. The water monitor (Varanus salvator) is a large lizard native to South East Asia. The sub species V.s salvator, is limited to Sri Lanka and are efficient carnivores and scavengers. Therefore, there is significant impact on forensic death investigations Case report: Case 1: A woman went missing. A vigorous search lead to the recovery of the body in a river, surrounded by water monitors. Injuries on the limbs simulated cut injuries. The skull had a depressed slashed cut exposing brain matter. Case 2: The dead body was located by searching along a path formed by water monitors. The neck injuries simulated cut throat. These two cases are discussed to highlight the medico-legal implications of water monitors in forensic death investigations. Conclusion: The presence of water monitors can be helpful in locating a missing body. However, it is necessary to interpret postmortem features cautiously in such cases as injuries caused by water monitors may result in artifacts, make injury interpretation difficult, make identification difficult, pose challenges to ascertaining the cause of death, and move objects from the scene.

Applying Knowledge of Species-Typical Scavenging Behavior to the Search and Recovery of Mammalian Skeletal Remains.

Forensic investigations involving animal scavenging of human remains require a physical search of the scene and surrounding areas. However, there is currently no standard procedure in the U.K. for physical searches of scavenged human remains. The Winthrop and grid search methods used by police specialist searchers for scavenged remains were examined through the use of mock red fox (Vulpes vulpes) scatter scenes. Forty-two police specialist searchers from two different regions within the U.K. were divided between those briefed and not briefed with fox-typical scavenging information. Briefing searchers with scavenging information significantly affected the recovery of scattered bones (χ(2) = 11.45, df = 1, p = 0.001). Searchers briefed with scavenging information were 2.05 times more likely to recover bones. Adaptions to search methods used by searchers were evident on a regional level, such that searchers more accustom to a peri-urban to rural region recovered a higher percentage of scattered bones (58.33%, n = 84).

Food for thought: using game cameras to better understand the movement of bones by scavenging in archaeological faunal assemblages

This paper questions our understanding of the movement of bones by animal scavengers in the archaeological record. Since assumptions regarding the effects of animal scavenging shape final interpretations of skeletal element frequencies in archaeological faunal assemblages, they are important for our understanding and reconstruction of ancient human behaviour. The results of a 4-year actualistic kangaroo scavenging study from Australia are used to question our understanding of the movement of the bone by contrasting visual data captured by motion-activated digital game cameras with traditional taphonomic studies using skeletal element frequencies. Game cameras are commonly used by ecologists to capture the behaviour of living species but have not yet been used in experimental archaeology where visually documenting animal scavenging behaviour can be used to understand the movement of carcasses and individual bones. Results suggest that traditional zooarchaeological analyses may not be accurate indicators of hunted versus scavenged prey in archaeological faunal assemblages. Moreover, they most certainly fail to document the entire suite of animals scavenging a carcass. These implications are discussed with particular reference to the ability to definitively ascertain the role of humans in the megafaunal extinction debate in Australia.

Archaeology, taphonomy, and historical ecology of Chesapeake Bay blue crabs (Callinectes sapidus)

Blue crabs (Callinectes sapidus), an important commercial and ecological species in the eastern United States, are a key part of Chesapeake Bay culture, tourism, and fisheries. Blue crab remains are rare in Middle Atlantic North American archaeological sites, however, leading to speculation that Native Americans did not eat crabs, that taphonomic processes and/or excavation strategies are not suitable to crab preservation or recovery, or that seasonal use of estuarine foods limited blue crab exploitation. We explore these hypotheses through examination of archaeological blue crab remains, analysis of allometric relationships to investigate changes in crab size, and experiments (soil pH, animal scavenging, etc.) focused on the preservation and recovery of blue crab remains. These data demonstrate that blue crab remains are fragile and that their preservation and recovery is strongly influenced by taphonomic processes, excavation strategies, and perhaps seasonal exploitation. Despite these potential biases, blue crabs have been identified in 93 Chesapeake Bay archaeological sites from at least 3200 years ago through the 20th century. Blue crabs were an important food source for Native Americans, EuroAmerican colonists, and African Americans, with size estimates demonstrating that a range of crab sizes were harvested in the past, including a higher proportion of large crabs than those found in the Bay today under the intense modern fishery. Our experimental and archaeological analyses provide an approach that can be used generally by archaeologists working in marine environments and on other species around the world.

Indoor postmortem animal scavenging - a case report

Discovery of decomposed bodies in domestic setting is not an uncommon occurrence. However postmortem animal scavenging of their owner is not commonly reported but can occur when the main predisposing factors are social isolation, living with free pets in the house and a medical condition causing sudden death. Sri Lanka Journal of Forensic Medicine, Science & Law-May 2014;5(1): 2-8 DOI: http://dx.doi.org/10.4038/sljfmsl.v5i1.7743

Animal scavenging and scattering and the implications for documenting the deaths of undocumented border crossers in the Sonoran Desert.

Since 1998, over 5500 people have died while attempting to cross the U.S.-Mexico border without authorization. These deaths have primarily occurred in the Arizona desert. Despite the high volume of deaths, little experimental work has been conducted on Sonoran Desert taphonomy. In this study, pig carcasses were used as proxies for human remains and placed in different depositional contexts (i.e., direct sunlight and shade) that replicate typical sites of migrant death. Decomposition was documented through daily site visits, motion-sensitive cameras and GIS mapping, while skeletal preservation was investigated through the collection of the remains and subsequent faunal analysis. Our results suggest that vultures and domestic dogs are underappreciated members of the Sonoran scavenging guild and may disperse skeletal remains and migrant possessions over 25 m from the site of death. The impact of scavengers and the desert environment on the decomposition process has significant implications for estimating death rates and identifying human remains along the Arizona/Mexico border.

Complementary Diet of Cathartes burrovianus (Cathartidae) With Fruit Elaeis guineensis (Arecaceae)

The mangrove swamps of the Guapi-Mirim Environmental Protection Area are rich in animal diversity. Due to its considerable size there is a generous supply of prey for any predator as well as significant food resources for animal scavengers. The vultures, which are carrion or predatory birds are included in the order Cathartiformes (Cathartidae) and the most common species in Brazil are: Cathartes aura (Linnaeus, 1758), Cathartes burrovianus Cassin, 1845; Cathartes melambrotus Wetmore, 1964; Coragyps atratus (Bechstein, 1793) and Sarcoramphus papa (Linnaeus, 1758). In the mangrove swamps of this protected area three species of vultures are commonly seen: C. aura, C. burrovianus e C. atratus. These three species basically have a diet of animal carcasses. All the Cathartes burrovianus observations carried out in this study were made in a small part of the mangrove swamps in the Guapi-Mirim APA, located in the district of Itambi, Itaboraí, Rio de Janeiro, Brazil. The observations were made every two weeks for a year and photography was used to record the birds. A total of 78 photographic observations were made of these birds (C. burrovianus) feeding on the fruit of the oil palm Elaeis guineensis Jacq. 1897. As the mangrove swamp has abundant food resources throughout the year, it was concluded that C. burrovianus feeds on the fruits of the palm E. guineensis not only as an alternative food in the absence of carcasses, but also a complement to their dietary needs. It is the first record of this feeding behavior. This fact may be related to the higher digestibility of carcasses consumed by these animals.