Scavenger-induced scattering of wild boar carcasses over large distances and its implications for disease management.

Vertebrate scavengers provide essential ecosystem services such as accelerating carrion decomposition by consuming carcasses, exposing tissues to microbial and invertebrate decomposers, and recycling nutrients back into the ecosystem. Some scavengers do not consume carcasses on site but rather scatter their remains in the surroundings, which might have important implications for nutrient transport, forensic investigations and the spread of diseases such as African Swine Fever. However, only a few studies have investigated and measured the scatter distances. Using wild boar (Sus scrofa) carcasses and limbs, we monitored scavenging behavior and measured scatter distances of mammals. We placed 20 carcasses (up to 25 kg) and 21 separate limbs equipped with very high frequency (VHF) transmitters and monitored scavenger activity using camera traps in a mountainous region in southeast Germany. Except for one carcass, all other carcasses and limbs were scattered. We measured 72 scatter distances (of 89 scattering events; mean = 232 m, maximum = 1250 m), of which 75% were dispersed up to 407 m. Scavengers moved scattered pieces into denser vegetation compared to the half-open vegetation at provisioning sites. Red foxes (Vulpes vulpes) were the most common scavenger species, contributing to 72 scattering events (58 measured scatter distances). Our results provide evidence of scatter distances farther than previously assumed and have far-reaching implications for disease management or forensic investigations, as the broader surroundings of carcasses must be included in search efforts to remove infectious material or relevant body parts for forensic analysis.

[Integrative microbial-zoological assessment of the postmortem period in forensic medical examination]. / Integrativnaya mikrobno-zoologicheskaya otsenka posmertnogo perioda dlya tselei sudebno-meditsinskoi ekspertizy.

THE AIM OF THE STUDY: Is a complex microbial-zoological characterization of the post-mortal period and ways of its determination during forensic examination. The heterotrophic component of the microflora of the corpse and its bed were studied using standard methods of microbiological research and PCR analysis, necrophilic insects - entomological method, and damages from some vertebrate animals - traditional methods of their analysis. We studied 125 corpses of humans, pigs, chickens, mice and some other representatives of mammal class weighing from 100 g to 100 kg at different times of decomposition. We isolated and studied more than 1000 isolates of microorganisms, more than 32 000 insects and more than 100 damages caused by rodents, dogs, cats and birds. We determined the main trends in microbial decomposition of dead bodies. The general characteristics of the corpse decomposition by insects are given and anatomical-topographical and morphological features of the corpse damage by some vertebrates are established. Significant The heterotrophic component of the microflora of the corpse and its bed were studied using standard methods of microbiological research and PCR analysis, necrophilic insects - entomological method, and damages from some vertebrate animals - traditional methods of their analysis. We studied 125 corpses of humans, pigs, chickens, mice and some other representatives of mammal class weighing from 100 g to 100 kg at different times of decomposition. We isolated and studied more than 1000 isolates of microorganisms, more than 32 000 insects and more than 100 damages caused by rodents, dogs, cats and birds. We determined the main trends in microbial decomposition of dead bodies. The general characteristics of the corpse decomposition by insects are given and anatomical-topographical and morphological features of the corpse damage by some vertebrates are established. Significant microbial and zoological characteristics of the post-mortem period have been identified, and ways of its establishment have been determined and confirmed by practical testing during forensic examination. A set of practical recommendations has been developed for forensic experts on the collection of necrophilous insects during the examination of the corpse at the scene and the tactics of the examination with the involvement of entomologists. The results obtained prove that there is a close correlation between the impact of vertebrate scavengers, necrophilic insects and the enzymatic activity of a specific community of heterotrophic microorganisms on the corpse.

Forensic experiments on animal scavenging: A systematic literature review on what we have and what we need.

Vertebrate scavengers frequently affect forensic casework by feeding on human remains or by scattering body parts and bones. Therefore, animal activity can influence complete recovery of bodies, trauma analysis, and the estimation of the postmortem interval (PMI), potentially hampering identification of the deceased and elucidation of the perimortem circumstances. Experimental research is well suited to investigate scavengers and their impact on carcasses over time, generating knowledge on the forensic relevance of certain scavenger species or communities. However, there are currently no systematised standards to conduct these investigations with a forensic focus, impeding comparison and synthesis of the studies. In our work, we performed a systematic literature review and found 79 publications featuring terrestrial experiments on vertebrate scavenging and/or scattering within a forensic context. We extracted 21 variables describing the study environment, experimental design and the specimens. The results show that there is considerable inconsistency in the study designs and that some of the variables are insufficiently reported. We point out research questions and areas that require attention in future studies, stressing the importance of infrequently mentioned or applied variables. Furthermore, we recommend guidelines to include and report a list of variables in forensic scavenging and scattering experiments. These guidelines will help standardising future research in the field, facilitating inter-study consolidation of results and conclusions, and consequently, inform forensic casework.

Functional differences in scavenger communities and the speed of carcass decomposition.

Carcass decomposition largely depends on vertebrate scavengers. However, how behavioral differences between vertebrate scavenger species, the dominance of certain species, and the diversity of the vertebrate scavenger community affect the speed of carcass decomposition is poorly understood. As scavenging is an overlooked trophic interaction, studying the different functional roles of vertebrate species in the scavenging process increases our understanding about the effect of the vertebrate scavenger community on carcass decomposition. We used motion-triggered infrared camera trap footages to profile the behavior and activity of vertebrate scavengers visiting carcasses in Dutch nature areas. We grouped vertebrate scavengers with similar functional roles. We found a clear distinction between occasional scavengers and more specialized scavengers, and we found wild boar (Sus scrofa) to be the dominant scavenger species in our study system. We showed that these groups are functionally different within the scavenger community. We found that overall vertebrate scavenger diversity was positively correlated with carcass decomposition speed. With these findings, our study contributes to the understanding about the different functional roles scavengers can have in ecological communities.

An experimental study of vertebrate scavenging behavior in a Northwest European woodland context.

Vertebrate scavengers can modify surface deposited human remains which can hinder forensic investigations. The effects of such scavenging vary between species and regions. Published research into the effects of the scavenging of human remains is dominated by work from North America with few studies covering Northwestern Europe. Forensic scientists, investigators, and police search officers in Northwestern Europe are often left questioning on a basic level as to which scavengers are active and how they might affect human remains. This paper presents the results of a field study utilizing deer (Cervus nippon; Capreolus capreolus) as surface deposits observed by motion detection cameras in a British woodland. The most common avian and rodent scavenger species recorded included the buzzard (Buteo buteo), carrion crow (Corvus corone), wood mouse (Apodemus sylvaticus), and gray squirrel (Sciurus carolinensis). The scavenging behaviors observed were affected by seasonality, rates of decomposition, and insect activity. Scavenging by buzzards, unlike carrion crows, was most frequent during fall to winter and prior to insect activity. Overall, avian scavengers modified and scavenged soft tissue. Rodents scavenged both fresh and skeletonized remains with gray squirrels only scavenging skeletal remains. Wood mice were most active in winter and scavenged both soft tissue and bone.