Pigs are best described as highly opportunistic omnivores. While they do not rely on scavenging for survival in the same way as a vulture, consuming refuse and carrion is a significant and natural part of their feeding strategy. This adaptability allows them to thrive in nearly every environment they inhabit, from wild forests to modern farms. Their diet is flexible, constantly adjusting to whatever resources are most easily accessible in their surroundings.
Defining Scavenging and Omnivory
To understand a pig’s diet, it is helpful to define omnivory and scavenging. An omnivore is an animal whose natural diet consists of both plant and animal matter, providing them with a wide variety of nutritional sources. Scavenging is a method of obtaining food by feeding on carrion—the remains of animals killed by predators or that died naturally—or by consuming general refuse.
Scavengers are classified as either obligate or opportunistic. Obligate scavengers, such as vultures, rely almost entirely on dead animal matter for sustenance. Pigs fall into the opportunistic category, meaning they are primarily omnivores that will readily scavenge when they encounter dead animals or other discarded food sources.
The Omnivorous Nature of Wild Pigs
Wild pigs, including feral swine and wild boar, are dynamic foragers whose diet is predominantly plant-based, though they actively seek animal protein. Their long, powerful snouts are used for “rooting,” a behavior where they push through soil and leaf litter to unearth underground food sources. This rooting primarily focuses on finding roots, bulbs, tubers, and invertebrates such as insect larvae and earthworms.
While much of their diet comes from foraging for plants and small invertebrates, wild pigs are also effective predators and scavengers. They consume small vertebrates, including snakes, frogs, and the eggs and young of ground-nesting birds and reptiles. Carrion is readily accepted and consumed whenever encountered, but it rarely forms the majority of their sustenance. Their ability to switch between foraging, rooting, and opportunistically consuming dead animals demonstrates their highly adaptable nature.
Their ecological impact stems directly from their feeding methods; constant rooting disturbs the soil structure, which encourages erosion and can negatively affect the seed survival and success of local plant species. Wild pigs adjust their diet seasonally, consuming more plant matter like acorns and nuts in the fall and winter, while increasing their consumption of insects and small animals during warmer months.
Domestic Pigs and Consumption of Refuse
The public association of pigs with scavenging is largely due to historical practices involving feeding domestic animals human waste. Historically, it was common practice to feed domestic pigs “swill,” which is a term for kitchen scraps and discarded food. In this human-influenced context, domestic pigs acted as scavengers of the human waste stream, consuming food waste that contained both plant and animal matter.
This practice was appealing because it provided a cheap source of feed and served as a form of waste disposal. Today, modern regulations heavily restrict the feeding of unprocessed refuse due to biosecurity concerns. Feeding pigs untreated food waste containing meat products is recognized as a major risk factor for spreading devastating diseases like Foot-and-Mouth Disease and African Swine Fever (ASF).
Because of this danger, many countries have implemented strict laws that prohibit feeding pigs any food waste that contains or has come into contact with meat or meat products. Outbreaks of ASF in Europe, for example, have been directly linked to domestic pigs and wild boar consuming contaminated pork products in discarded refuse. While pigs retain the biological capacity to consume nearly anything, modern farming practices and disease control efforts have largely shifted their diet to commercially prepared feed and agricultural byproducts.