Vultures and others scavenger vertebrates associated with man-sized pig carcasses: a perspective in Forensic Taphonomy

SHORT COMMUNICATION

Vultures and others scavenger vertebrates associated with man-sized pig carcasses: a perspective in Forensic Taphonomy

Caroline Demo^I; Edison Rogério Cansi^I; Cecília Kosmann^I; José Roberto Pujol-Luz^I,II

^INúcleo de Entomologia Forense, Departamento de Zoologia, Universidade de Brasília. 70910-900 Brasília, DF, Brazil

^IICorresponding author. E-mail: [e-mail]

ABSTRACT

The activity of vertebrates that feed on corpses can modify the chronology of the decomposition process and interfere with postmortem interval estimates. Further, by destroying the soft parts of the cadaver, scattering, burying or causing the disappearance of bones, it can entirely change the crime scene. In this study, we simulated a clandestine cemetery in an area of Cerrado located inside a farm in Brasília, Distrito Federal. Three domestic pigs of the size of a human of about 60 kg were placed on the ground in different periods of 2010 and 2011. We recorded four species of birds and one of mammal eating the carcasses: 1) Cathartidae: Coragyps atratus (Bechstein, 1973), Cathartes aura (Linnaeus, 1758), Sarcoramphus papa (Linnaeus, 1758); 2) Falconidae: Caracara plancus (Miller, 1777); and 3) Felidae: Leopardus pardalis (Lund, 1840). The behavior of these animals interfered in the decomposition process and resulted in the dispersion and loss of bony parts.

Key words: Cerrado; chronothanatognosis; clandestine cemeteries; decomposition; necrophagy.

Forensic Taphonomy is applied in several situations where the causes of death, or evidence, cannot be explained through routine methods (e.g., mass accidents, summary and mass executions, clandestine cemeteries) (UN 1991). The activities of scavengers animals, specially vultures, can modify the crime scene and generate several artifacts (Morton & Lord 2006, Carter et al. 2007, Ururahy-Rodrigues et al. 2008, Reeves 2009), as the concealment of the body and/or its dismemberment (Haglund & Sorg 1997, Spradley et al. 2012). Either opportunistically or by lack of food, some predators such as big cats (Rippley et al. 2012), rodents, dogs, and coyotes (Haglund 1997a,b) may occasionally feed on the carcasses, dismantling and moving it. The activity of these animals can modify the rate of decomposition and the post-mortem events, as well as the estimative of the post-mortem interval (PMI) (Spradley et al. 2012).

During 2010 and 2011, three man-sized pigs (60 kg) were placed on the ground of a savannah-like formation (Cerrado) in a farm near to the urban area of Brasília, Distrito Federal, in order to simulate a clandestine cemetery. With the aim to record the vertebrates that fed on the carcasses, we installed a camera trap near them and left it there for 24 hours/day, from the moment of death until skeletonization.

The camera took a total of 831 photos. Five species of vertebrates, four birds and one mammal (Figs 1-6), were recorded: 1) Cathartidae: Coragyps atratus (Bechstein, 1973), Cathartes aura (Linnaeus, 1758), Sarcoramphus papa (Linnaeus, 1758); 2) Falconidae: Caracara plancus (Miller, 1777); and 3) Felidae: Leopardus pardalis (Lund, 1840). The presence of the scavenger vertebrates was associated with the five stages of decomposition: initial, bloated, decay, postdecay, and dry (Table I).

Vultures, one of the most versatile scavenger birds, were the only vertebrates observed during the experiments that are known to have a diet composed almost entirely of carcasses (Ruxton & Houston 2004). In Brazil, they are represented by six species: C. atratus, C. aura, Cathartes burrovianus (Cassin, 1845), Cathartes melambrotus (Wetmore, 1964), and S. papa. These birds are usually the first vertebrate scavenger to access the body (DeVault et al. 2004, Kjorlien et al.2009, O'Brien et al. 2010), and can eat meat in advanced stage of putrefaction. The most remarkable interaction we observed was the lack of competition for food between C. plancus and C. atratus. The southern crested caracara (C. plancus) is not limited to consuming carcasses, it can also eat the remains around it, beetle larvae and other insects that move away from the body. As a result of the intense activity of C. atratus on the carcasses, large bones, for instance the scapula and femur, were taken about six meters away from the site of decomposition. The desarticulation and transport of flesh and skeletonized remains is a well-known phenomenon attributed to scavenger birds, especially vultures (Reeves 2009, Spradley et al. 2012).

Despite the fact that big cats are not commonly found feeding on carcasses, Rippley et al. (2012) reported bob cats Lynx rufus (Schreber, 1777) feeding on human corpses. The ocelot (L. pardalis) has a solitary and terrestrial habits, predominantly nocturnal, and feeds on small vertebrates (DiBitetti et al. 2006). Nevertheless, in our experiment, when L. pardalis fed on a carcass, it displaced it from its original position (Figs 7 and 8). Mechanical movements, spontaneous or deliberate, become important events for the interpretation of the crime scenes. Allied to this, moving the carcasses facilitates the dispersion of the body parts, as observed by Ururahy-Rodrigues et al. (2008).

Studies involving the reconstruction of crime scenes are important and must consider the activity of scavengers in order to separate the peri-mortem and post-mortem events in the investigation (Ubelaker 1997).

ACKNOWLEDGEMENTS

The authors thank Miguel A. Marini (UnB) for the identification of the birds; José M. da S. Diogo, head of Fazenda Água Limpa (UnB), for the logistic help with the experiments; Hélio R. da Silva (UFRRJ) for reviewing the manuscript. We are also grateful to Hélio Spindula for his help in the field work and Karine B.B. Cordeiro for the images edition. To FAPDF and CNPq for the grants.

LITERATURE CITED

Submitted: 18.X.2012; Accepted: 13.IV.2013.

Editorial responsibility: Kleber Del Claro

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Publication Dates

• Publication in this collection
  19 Nov 2013
• Date of issue
  Oct 2013

History

• Received
  18 Oct 2012
• Accepted
  13 Apr 2013