Identifying forensically relevant urban scavengers in Johannesburg, South Africa

Keyes, Craig Adam; Myburgh, Jolandie; Brits, Desiré

doi:10.1016/j.scijus.2022.04.007

Cited by 6 publications

(7 citation statements)

References 51 publications

(84 reference statements)

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“…For the same reason, multiple carcasses were not used at each site, even though this would increase the statistical validity of the data. While multiple carcasses are sometimes used in scavenging studies to ensure reliable trends can be reported [24, 28, 35], the use of multiple carcasses at our sites would have increased the likelihood of individual scavengers feeding on multiple carcasses, and thus reduced their feeding behavior at a single carcass as would occur in a natural scavenging environment (and also in a forensic context). Additionally, the nutrient pulse produced by multiple carrion could change the structure and composition of the scavenger guilds at a local scale [28].…”

Section: Discussionmentioning

confidence: 99%

“…When conditions are optimal, such as when other competing scavengers are less present (e.g., as a result of bird migration or fenced study sites), small mammals have been reported as prevalent scavengers in forensically relevant studies. These include the Cape gray ( Herpestes pulverulentus ), slender ( Galerella sanguinea ), and banded ( Mungos mungo ) mongoose in South Africa [9–11, 28, 35], the red fox ( V. vulpes ) and Eurasian badger ( Meles meles ) in the United Kingdom [8], along with the Virginia opossum ( Didelphis virginiana ) [2, 3], northern raccoon ( P. lotor ) [2, 20], bobcat ( Lynx rufus ) [5], and striped skunk ( M. mephitis ) [2, 25] in North America. Such information is important for interpreting soft and hard tissue loss in forensic death investigations, particularly when such scavengers are either unknown for a biogeoclimatic region, or are not presumed to be the dominant scavenger for the region where human remains are discovered.…”

Section: Discussionmentioning

confidence: 99%

“…Additionally, the nutrient pulse produced by multiple carrion could change the structure and composition of the scavenger guilds at a local scale [28]. Concerns of "scavenger swamping" have been raised by ecologists in prior studies, and this issue remains unresolved in both ecological and forensic research [28,[35][36][37][38]. However, our future studies will continue to employ single carcasses at multiple sites to increase the robustness and broader interpretability of the trends observed.…”

Section: Limitations Of the Studymentioning

confidence: 99%

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Seasonal impact of scavenger guilds as taphonomic agents in central and northern Ontario, Canada

Forbes

Samson

Watson³

2022

Journal of Forensic Sciences

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The process of human decomposition is driven by biological decomposers, mainly bacteria, vertebrates, and invertebrate scavengers. When vertebrate scavengers have access to a body, they can considerably accelerate decomposition through consumption of soft tissue and dispersal of skeletal elements. Presently, there are limited data available on vertebrate scavenging activity in Canada, particularly in densely populated provinces such as Ontario. This study aimed to determine which vertebrate species belong to the scavenger guilds in central and northern Ontario, and the impact of season and habitat on these taphonomic agents. Seasonal trials were conducted in summer, fall, and spring of 2020/2021 with pig carcasses placed in open (grassland) and closed (forest) sites. Vertebrate scavenger activity was recorded continuously using cellular and non‐cellular trail cameras. Photographs were analyzed to identify species, quantify feeding intensity, and document scavenging behavior. We identified four mammalian scavengers, namely coyote, red fox, fisher, and pine marten, and three avian scavengers, namely bald eagle, turkey vulture, and American crows/northern ravens (grouped as corvids) across the trials. Season impacted scavenger presence with feeding and loss of soft tissue occurring more quickly in the summer, followed by spring and fall. None of the scavengers demonstrated a clear preference for the open versus closed sites. Our findings have identified the most prevalent vertebrate scavengers in central and northern Ontario and their taphonomic impact on soft and hard tissues. It is important to consider these agents and their ability to degrade and disperse remains during the search and recovery of human remains.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Limitations Of the Studymentioning

confidence: 99%

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Seasonal impact of scavenger guilds as taphonomic agents in central and northern Ontario, Canada

Forbes

Samson

Watson³

2022

Journal of Forensic Sciences

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“…Although the Cape gray mongoose was the only observed scavenger, this was not unexpected; exclusive scavenging by this species has been noted in this area before [4, 13–15, 46]. This mongoose, along with other species, has also been documented in other South African contexts [24, 47–49]. The single carcasses experienced more mongoose scavenging than the multiple carcasses for each season.…”

Section: Discussionmentioning

confidence: 76%

“…African contexts [24,[47][48][49]. The single carcasses experienced more mongoose scavenging than the multiple carcasses for each season.…”

Section: Scavengingmentioning

confidence: 99%

Portion size matters: Carrion ecology lessons for medicolegal death investigations—A study in Cape Town, South Africa

Spies,

Finaughty,

Gibbon

2023

Journal of Forensic Sciences

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Forensic taphonomic studies are regionally specific and improve time since death estimates for medico‐legal casework. Within forensic taphonomy and carrion ecology, vertebrate scavengers are under‐researched with many studies conducted using multiple, unclothed carcasses. This is a forensically unrealistic experimental design choice with unknown impact. The effect of variation in carrion biomass on the decomposition ecosystem, particularly where vertebrate scavengers are concerned, requires clarification. To assess the effect of carrion biomass load on vertebrate scavenging and decomposition rate, seasonal baseline data for single, clothed ~60 kg porcine carcasses were compared to clothed multiple‐carcass deployments, in a forensically relevant habitat of Cape Town, South Africa. Decomposition was tracked via weight loss and bloat progression and scavenging activity via motion‐activated cameras. The single carcasses decayed more quickly, particularly during the cooler, wetter winter, strongly correlated with concentrated Cape gray mongoose (Galerella pulverulenta) scavenging activity. On average and across seasons, the single carcasses lost 68% of their mass by day 32 (567 accumulated degree days [ADD]), compared to 80 days (1477 ADD) for multi‐carcass deployments. The single carcasses experienced substantially more scavenging activity, with longer visits by single and multiple mongooses, totaling 53 h on average compared to 20 h for the multi‐carcass deployments. These differences in scavenging activity and decay rate demonstrate the impact of carrion biomass load on decomposition for forensic taphonomy research. These findings need corroboration. However, forensic realism requires consideration in taphonomic study design. Longitudinally examining many single carcasses may produce more forensically accurate, locally appropriate, and usable results.

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

Keyes

2024

Int J Legal Med

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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.

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Identifying forensically relevant urban scavengers in Johannesburg, South Africa

Cited by 6 publications

References 51 publications

Seasonal impact of scavenger guilds as taphonomic agents in central and northern Ontario, Canada

Seasonal impact of scavenger guilds as taphonomic agents in central and northern Ontario, Canada

Portion size matters: Carrion ecology lessons for medicolegal death investigations—A study in Cape Town, South Africa

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

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