Keeping domestic cats indoors is best for their health and the environment, according to a new study from University of Maryland. The experts report that humans are primarily responsible for the risks associated with free-roaming cats, such as threats to native animal populations and the potential for disease transmission.
“Free-roaming domestic cats (Felis catus) are known to pose threats to ecosystem health via transmission of zoonotic diseases and predation of native wildlife,” wrote the study authors. “Likewise, free-roaming cats are also susceptible to predation or disease transmission from native wildlife.”
The researchers analyzed data from the D.C. Cat Count, a survey that included 60 wildlife cameras across 1,500 sites. The cameras revealed where the cats frequently overlapped with native wildlife.
“We discovered that the average domestic cat in D.C. has a 61% probability of being found in the same space as racoons – America’s most prolific rabies vector – 61% spatial overlap with red foxes, and 56% overlap with Virginia opossums, both of which can also spread rabies,” explained study lead author Daniel Herrera. “By letting our cats outside we are significantly jeopardizing their health.”
The survey cameras also revealed the native animals that were commonly preyed upon by domestic cats, including grey squirrels, chipmunks, cottontail rabbits, groundhogs, and white footed mice. The experts noted that by hunting these animals, cats can reduce biodiversity and degrade ecosystem health.
“Many people falsely think that cats are hunting non-native populations like rats, when in fact they prefer hunting small native species,” explained Herrera. “Cats are keeping rats out of sight due to fear, but there really isn’t any evidence that they are controlling the non-native rodent population. The real concern is that they are decimating native populations that provide benefits to the D.C. ecosystem.”
Overall, the study showed that the presence of cats increased with human population density, yet decreased with tree cover and other natural features that are associated with a greater presence of wildlife. Herrera said that these associations run counter to arguments that free-roaming cats are simply stepping into a natural role in the ecosystem by hunting wildlife.
“These habitat relationships suggest that the distribution of cats is largely driven by humans, rather than natural factors,” noted Professor Travis Gallo. “Since humans largely influence where cats are on the landscape, humans also dictate the degree of risk these cats encounter and the amount of harm they cause to local wildlife.”
The study is published in the journal Frontiers in Ecology and Evolution.
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