The sample included the skeletons of four pig carcasses (Sus scrofa domesticus) that had been recovered after they had been scavenged and scattered in two previous studies [11, 12]. Two skeletons were scavenged by slender mongooses (Galerella sanguinea) [12] and two were scavenged by black-backed jackals (Canis mesomelas) [11]. The scattering patterns of each scavenger were mapped prior to the recovery of their scavenged pig carcasses in the initial studies [11, 12].

The present study was performed at the Frakenwald Research Site (Fig. 1), which is a research site for forensic taphonomic research in Johannesburg, South Africa [12, 13]. This environment replicates those where most scattered human remains are recovered from in a South African forensic context (open grassland with low shrubbery and sparce trees).

Frankenwald research site

The scattering pattern of each scavenger was recreated in duplicate (one for the grid search and one for the link search) in a separate location at the research site. The slender mongoose scattering included 17 skeletal elements scattered over an area of 113m2 (Fig. 2). The black-backed jackal scattering included 28 skeletal elements scattered over an area of 701m2 (Fig. 3). Game trails created by the scavenging animals in the initial studies [11, 12] were recreated to ensure that visual cues observed in the previous studies were present in the present study. Apart from recreating game trails, the impact of vegetation was not specifically accounted for in this study because the environment was a replicate of the initial studies [11, 12], which included areas with long dry grass.

Slender mongoose scattering pattern on a north-south y-axis and east-west x-axis. (Points indicate individual skeletal elements or a grouping of skeletal elements in very close proximity or an articulation of skeletal elements. Origin 0.0 indicates the original site of deposition prior to scattering. Distance is measured in meters)

Black-backed jackal scattering pattern on a north-south y-axis and east-west x-axis. (Points indicate individual skeletal elements or a grouping of skeletal elements in very close proximity or an articulation of skeletal elements. Origin 0.0 indicates the original site of deposition prior to scattering. Distance is measured in meters)

The study participants included twelve Bachelor of Health Sciences Honours in Forensic Sciences students at the University of Witwatersrand. The participants were randomly divided into two groups, each of which was assigned a different search method to recover their assigned pair of slender mongoose and black-backed jackal scattered remains. The first group performed the grid search method, and the second group performed the link search method. Each group was trained separately on how to perform their respective search method.

The grid search method does not require any context or information regarding the environment, the scavenging animals, or their behaviors. As such, the group assigned this method was not provided with any context and was instructed to follow the grid search method.

The link search method requires knowledge of possible scavenging animals present in the environment and their scattering behaviors. The group assigned this method was informed that the common scavenger guild that inhabits urban and peri-urban South African veld (i.e., grassland) environments included common large-spotted genet (Genetta tigrine), black-backed jackal (Canis mesomelas), slender mongoose (Galerella sanguinea), water mongoose (Atilax paludinosusis), yellow mongoose (Cynictis penicillata), Cape porcupine (Hystrix africaeaustralis), honey badger (Mellivora capensis), and domestic dogs (Canis familiaris). The group was informed of the general scattering behaviors of dominant mammalian scavengers common in South African veld environments. This included the scattering of remains in two different but uniform directions, with the two directions forming a 90-de-gree arc the original deposition site (or site where a body or carcass was originally whole, prior to dismemberment or disarticulation by scavengers) [11, 12]. They were also informed that scavengers often scatter remains along game trails towards a burrow or beneath foliage [11, 12]. The group was also informed that the scattering range was relative to the size of the dominant scavenging species [11, 12].

Each group was given a data collection sheet to record when and which skeletal element was located and flags to mark the location of the located skeletal element. Participants were not informed on how many bones were present at the site, nor were they given a time limit to search for the remains. Each group was asked to record what time they started the search, when each bone was located, and when they ended their search. Each group was first transported to their assigned site with remains scattered in the recreated black-backed jackal scattering pattern. This was followed by their transportation to their respective site with remains scattered in the recreated slender mongoose scattering pattern.

At the completion of the recovery at both sites, participants completed a questionnaire that reviewed their experiences with their assigned search method. The questionnaire was comprised of eight questions in the form of a five-point Likert scale. The questionnaire assessed the participants’ perception of the effectiveness of each search method. Each participant signed a participation consent form that informed them that there were no personal risks or benefits to participating in the study, that no personal information was recorded, all answers were anonymous, they were under no obligation to participate, and they could withdraw from the study at any stage.

Descriptive statistics were used to determine the effectiveness of each search method by comparing the number of skeletal elements collected and a paired t-test (5% level of significance) was used to compare the time of recovery of each skeletal element and the Likert scale answers for each question in the questionnaire.

Ethical clearance for the study was granted by the University of the Witwatersrand’s Animal Research Ethics Committee (waiver numbers: 17-04-2018-O and 2021-04-04-O).