New Research Reveals Why You Shouldn’t Let Your Cat Outside
By UNIVERSITY OF MARYLAND
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| An infographic describing the research. Credit: Daniel Herrera |
The next
time you let your cat outside for its daily adventure, you may want to
reconsider. A new study by University of Maryland researchers has found
that keeping cats indoors can significantly reduce the risks of transmitting
diseases and hunting wildlife, which can have a negative impact on native
animal populations and biodiversity.
The
study’s findings were based on data from the D.C. Cat Count, a Washington,
D.C.–wide survey that used 60 motion-activated wildlife cameras placed across
1,500 sampling locations. The researchers emphasized that humans bear a primary
responsibility in reducing these risks by keeping cats indoors.
The
cameras recorded what cats preyed on and demonstrated how they overlapped with
native wildlife, which helped researchers understand why cats and other
wildlife are present in some areas, but absent from others. The paper was
recently published in the journal Frontiers in Ecology and
Evolution.
“We discovered that the average domestic cat in D.C. has a 61% probability of being found in the same space as raccoons — 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,” said Daniel Herrera, lead author of the study and Ph.D. student in UMD’s Department of Environmental Science and Technology (ENST). “By letting our cats outside we are significantly jeopardizing their health.”
In addition to the risk of being exposed to diseases that they can then bring indoors to the humans in their families (like rabies and toxoplasmosis), outdoor cats threaten native wildlife. The D.C. Cat Count survey demonstrated that cats that are allowed to roam outside also share the same spaces with and hunt small native wildlife, including grey squirrels, chipmunks, cottontail rabbits, groundhogs, and white-footed mice. 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.”
In
general, Herrera found that the presence of wildlife is associated with tree
cover and access to open water. On the other hand, the presence of cats
decreased with those natural features but increased with human population
density. He says 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,” explained Travis Gallo, assistant
professor in ENST and advisor to Herrera. “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.”
Herrera
encourages pet owners to keep their cats indoors to avoid potential encounters
between their pets and native wildlife. His research notes that feral cats are
equally at risk of contracting diseases and causing native wildlife declines,
and they should not be allowed to roam freely where the risk of overlap with
wildlife is high – echoing previous calls for geographic restrictions on where
sanctioned cat colonies can be established or cared for.
Reference:
“Spatial and temporal overlap of domestic cats (Felis catus) and
native urban wildlife” by Daniel J. Herrera, Michael V. Cove, William J.
McShea, Sam Decker, D. T. Tyler Flockhart, Sophie M. Moore and Travis Gallo, 21
November 2022, Frontiers in Ecology and Evolution.
DOI:
10.3389/fevo.2022.1048585