Rats are among the most widespread and successful mammals on the planet, thriving in nearly every environment from wilderness to dense urban centers globally. The concept of rats consuming human or animal remains is a topic that often arises from dark curiosity and is frequently sensationalized in popular culture. Understanding the science behind their feeding habits requires examining their biological status as highly adaptable creatures and opportunistic feeders. This factual discussion of rat behavior is grounded in forensic science and ecological studies.
The Direct Answer: Rat Necrophagy and Omnivorous Diet
Rats, particularly the common urban species such as the brown rat (Rattus norvegicus), are true omnivores, meaning their diet naturally incorporates both plant and animal matter. This biological classification means they are capable of consuming a wide variety of food sources, including human or animal remains, a behavior known as necrophagy. This consumption is not a matter of preference but a function of their opportunistic need for energy and protein. The primary diet of wild rats generally prioritizes easily accessible resources like grains, seeds, fruits, and small invertebrates. However, their digestive system is highly adaptable, allowing them to process nearly any organic material they encounter. When typical food sources are scarce, the soft tissues of a carcass represent a viable and energy-rich meal. Rats will feed on soft tissue throughout all stages of decomposition if the opportunity presents itself.
Environmental Triggers for Consumption
The consumption of remains is primarily driven by environmental pressure, specifically the scarcity or inaccessibility of primary food sources. When rats are confined to a space with a body, such as in closed urban areas, sewers, or abandoned structures, the remains effectively become a stationary, non-competitive food source. This behavior is strongly linked to survival, acting as a fallback mechanism when the local ecosystem cannot support the rat population’s daily caloric needs. Scavenging is also observed in conjunction with population density and competition, where the increased pressure for resources forces individual rats to exploit less desirable food items. Furthermore, remains can offer a protective microclimate, with rats sometimes using a body for both food and refuge. Observations in forensic settings have shown that rats can exhibit selective feeding, sometimes bypassing organs that are purulently altered or diseased.
Identifying Rat Feeding Damage
Forensic science often distinguishes rat feeding damage by specific, characteristic patterns left on soft tissue and bone. Rats use their upper and lower pairs of sharp incisors in a gnawing action, which typically produces circular defects with finely serrated, irregular margins. These wounds may also show distinct, parallel cutaneous lacerations, which correspond to the spacing of the rodent’s teeth and are diagnostic of rat activity.
Rats tend to target the most exposed, soft, and moist areas of the body first, such as the eyelids, nose, lips, and the soft tissue on the back of the hands and feet. Once soft tissue is consumed, rats may also gnaw on bone to access fat-laden cancellous bone, which is rich in nutrients. They often target areas of minimal cortical thickness, such as the ends of long bones or small bones, to reach the marrow cavity inside.
Comparing Rats to Other Scavengers
The impact of rat scavenging is generally localized and distinguishable when compared to the feeding patterns of other common urban and wild scavengers. Unlike larger carnivores, such as raccoons or dogs, which can widely scatter remains, the damage caused by rats is typically confined to the immediate area of the body. Avian scavengers like buzzards and crows primarily modify and consume soft tissue, but their feeding marks are distinct from the parallel indentations left by rodent incisors.
Smaller rodents, such as wood mice, also scavenge but typically focus on skin and fat without consuming enough muscle to expose bone. A key difference between brown rats and other bone-gnawing rodents, like gray squirrels, lies in their motivation. While gray squirrels primarily gnaw bone for minerals like calcium after soft tissue is gone, brown rats are focused on accessing the fat and nutrients found within the bone marrow. This difference results in brown rats attacking bones earlier and targeting thinner sections.