How Feralized Animals Affect The Environment
Human development and urbanization affect wild animals in a number of ways. One of these is domestication, the process of a wild animal being brought out of the wild and into human care. Domestication changes animals physically and biologically through artificial selection, dietary changes, and other human-controlled factors — think of the long process that leads to wolves becoming chihuahuas. But sometimes domestic animals make their way back into the wild, becoming feral. This paper reviews research on feral animals to explore their under-appreciated effects on ecosystems.
When animals become feral, they don’t just revert back to their pre-domestic forms; they become new animals entirely. Domestication changes animals and can also take them far away from their original environments. Wolves lived only in the northern hemisphere, but they found homes globally after being domesticated into dogs. So, when those animals enter back into the wild, they enter a new environment with new physicality and biology, and develop into new creatures. When dogs feralized in Australia, for example, they became dingos.
The authors suggest that feral animals may be able to replace certain extinct species if they are ecologically similar. This has been seen in attempts to repopulate wild horses and a few other species, but more research is needed to say if this method could work reliably in the future.
Unfortunately, most known effects of feral animals are negative. When animals feralize, they enter into an established ecosystem and throw it off balance. Feral animals can compete with native predators, hunt native prey to the point of extinction, and threaten the ecosystem’s biodiversity. They can outcompete native species, reducing their populations. Even feral species that occupy a previously unoccupied ecological niche may indirectly affect native species, such as by changing seed dispersal patterns.
Feral animals also mingle with wild animals, creating hybrid animals — for example, piglets have increasingly appeared in wild boar populations. Species may interbreed with the species they originally evolved from or with less closely related species. This causes more of an ecosystem’s gene pool to be taken up by feral and hybrid animals. Over time, the original wild animal could be erased from the gene pool entirely. This happened to the aurox, the wild ancestor of the domestic cow, and currently threatens wild yaks, which may be genetically replaced by their domestic counterparts.
Feral animals can also carry pathogens and bacteria that spread new diseases through the wild. Feral animals that stay near human environments, such as cats and pigeons, are sometimes seen as nuisances, which can damage public support for conservation and animal advocacy.
Urban areas in particular threaten surrounding ecosystems with feralization. Since cities have higher concentrations of humans and domestic animals, there are more feral animals. Feralization can occur when animals escape human ownership or when they’re intentionally released into the wild, such as pigeons being released to fly free. The large numbers of feral animals coming from urban areas disrupt food chains and wild animals in nearby ecosystems. The authors speculate that feralization plays a large role in the current biodiversity crisis, but more research is needed to see the extent of the effects.
Feral animals pose a serious ecological threat that has gone largely unnoticed, and should be taken seriously by animal advocates. This problem stems largely from the high demand for domestic animals that end up escaping or being released. If domestic animals are not properly cared for, they may roam into the wild and eventually leave their human owners permanently. This happens frequently with cats in particular, who can harm local bird populations when they become feral. The effects of feralization also mean people should think twice before setting an animal free. Although many release animals out of compassion, this could be doing more harm than good.
https://www.mdpi.com/2076-2615/13/4/747