Domesticated dogs tend to be widely loved as companions and I am no exception to this feeling. Hence I was startled to learn that feral and free-roaming dogs may be responsible for the extinction of a large number of animal species.
There are now an estimated 1 billion domestic dogs across their near-global distribution.
Domestic dogs include feral and free-ranging animals (such as village and camp dogs), as well as those that are owned by and completely dependent on humans (pet dogs).
We found that dogs are implicated in the extinction of at least 11 species, including the Hawaiian Rail and the Tonga Ground Skink. Dogs are also a known or potential threat to 188 threatened species worldwide: 96 mammal, 78 bird, 22 reptile and three amphibian species. This includes 30 critically endangered species, two of which are classed as “possibly extinct”.
These numbers place dogs in the number three spot after cats and rodents as the world’s most damaging invasive mammalian predators.
Aside from simply killing animals, dogs can harm wildlife in other ways, such as by spreading disease, interbreeding with other canids, competing for resources such as food or shelter, and causing disturbances by chasing or harassment. For example, contact with domestic dogs increases disease risk for endangered African Wild Dogs in Kenya.
Part of the problem is that when wild animals perceive dogs as a threat, they may change their behaviour to avoid them. One study near Sydney found that dog walking in parklands and national parks reduced the abundance and species richness of birds, even when dogs were restrained on leads.
I am glad to report that Baxter the Wonder Dog has not killed any animal, though he does vigorously bark and chase after squirrels, rabbits, and birds that come to our garden.