Original article here.
Tuesday, January 21, 2020
The setting of a research institute’s “body farm” exposes deceased bodies to outdoor elements, providing real-time information about the decompositional changes that occur in human bodies post-mortem. These elements include temperature, precipitation, soil acidity, maggots and other insects, and scavenging animals—including feral cats.
In a new paper published in the Journal of Forensic Sciences, Sara Garcia and co-authors documented two specific incidences of the scavenging patterns of feral cats on human remains at Colorado Mesa University’s Forensic Investigation Research Station (FIRS). Due to the prevalence of feral cats across the United States (and world), understanding the patterns and behaviors of these cats is important to distinguishing between perimortem and postmortem tissue damage in corpses exposed to outdoor settings.
"Tissue damage that is caused by postmortem scavenging may be confused with perimortem trauma and may interfere with law enforcement's estimation of postmortem interval," lead author Sara Garcia, a student at Colorado Mesa University, told Forensic. "Postmortem scavenging may also distort or conceal soft tissue trauma that can be used by law enforcement agencies to determine the cause and manner of death."
In both cases profiled by Garcia and co-authors, the cats favored soft tissue during early decomposition and no later, although the specific method of consumption was different between the two cats. Interestingly, each cat scavenged on a specific body for more than two weeks—showing absolutely no interest in the other 40+ bodies in the same state of composition nearby.
The body of a 79-year-old woman was placed outside at FIRS 13 days after death. Approximately 5 days after placement, motion-activated infrared game cameras detected a striped cat tearing tissue from the arm of the donor body. The cat continued to scavenge the same body almost nightly for 35 days. Initially, it consumed tissue from the left arm and adjacent chest area, focusing on the dermal and fat layers. Only after consuming most of the fat tissue on the arm did the cat consume muscle tissue, eventually exposing the humerus bone.
A black cat descended on the remains of a 70-year-old man six days after placement of the body in the farm, 11 days after death. This cat focused on the left shoulder, the lower abdomen and the left arm. After the first time, the same cat returned to the same body multiple times a night for 10 of the next 16 nights. After a month-long hiatus, the black cat returned for two nights.
Garcia and co-authors report the tissue removal process differed between the two cats. The striped cat in the first case pulled the outer tissue back to gain access to the underlying dermis, while the black cat in the second case consumed tissue layers from superficial to deep without a clear preference.
For both cats scavenging ceased at moist decomposition, 21 to 40 days post-placement in the body farm. The authors show clear evidence that feral cats prefer tissue in earlier stages of decomposition. Additionally, neither cat showed interest in nearby bodies in similar decomposition stages to their selected target. The authors attribute this at least partly to the “novelty effect," or the idea that feral cats prefer a food source that is already familiar.
"The novelty effect combined with neophobia (the tendency for cats to reject food unfamiliar to them) could explain why in both cases the cats only scavenged a single donor and ignored all the adjacent donors," said Garcia. "When the cat found a suitable food source, it stayed with it rather than taking the risk of scavenging other nearby donors when there was no guarantee that the new food source would also be suitable."
The study authors point out these are just two cases and can not be considered a pattern for feral cats, but urge further documentation to establish patterns and variations in behavior, including based on the location of a body farm.
"The scavenging we observed occurred in colder months when other food sources may have been limited. In a different climate and different food sources for the feral cat populations, there may be differences in behaviors timing and patterning of scavenging," said Garcia.