Birds alighting on driveways and baby bunnies munching on lawn grass shouldkeep something in mind: Beware the house cat.
A new study shows that hunting by house cats can have big effects on localanimal populations because they kill more prey, in a given area, than similar-sized wild predators. This effect is mostly concentrated relatively close to apet cat’s home, since most of their movement was a 100-meter radius of theirhomes, usually encompassing a few of their neighborhood’s yards on eitherside.
Researchers from NC State University and the North Carolina Museum of NaturalSciences collaborated with scientists and citizen scientists from sixcountries to collect GPS cat-tracking data and prey-capture reports from 925pet cats, with most coming from the U.S., U.K, Australia and New Zealand.
“Since they are fed cat food, pets kill fewer prey per day then wildpredators, but their home ranges were so small that this effect on local preyends up getting really concentrated,” said Roland Kays, the paper’s leadauthor. “Add to this the unnaturally high density of pet cats in some areas,and the risk to bird and small mammal population gets even worse.
“We found that house cats have a two- to 10-time larger impact on wildlifethan wild predators — a striking effect,” he said.
The researchers focused on the ecological impact of house cats — as opposed toferal cats — and enlisted hundreds of pet owners to track their cats to seewhere they went and report on the number of dead critters they brought home.Inexpensive GPS tracking devices measured distances traveled by these housecats, which spent their days both indoors and outdoors.
“We knew cats were killing lots of animals — some estimates show that cats inNorth America kill from 10 to 30 billion wildlife animals per year — but wedidn’t know the area in which that was happening, or how this compared withwhat we see in nature,” Kays said.
The researchers calculated the amount of prey killed per year by house catsand divided the number by the area in which the cats hunted. Some adjustmentswere made to the prey count as cats don’t necessarily bring all their killshome.
The study showed that house cats killed an average of 14.2 to 38.9 prey per100 acres, or hectare, per year.
The study also showed that cats do much of their damage to wildlife indisturbed habitats, like housing developments.
“Because the negative impact of cats is so local, we create a situation inwhich the positive aspects of wildlife, be they the songs of birds or thebeneficial effects of lizards on pests, are least common where we wouldappreciate them most,” said study co-author Rob Dunn, William Neal ReynoldsDistinguished Professor of Applied Ecology at NC State. “Humans find joy inbiodiversity, but we have, by letting cats go outdoors, unwittingly engineereda world in which such joys are ever harder to experience.”
NC State’s Arielle W. Parsons and Brandon Mcdonald co-authored the paper.Other co-authors include Troi Perkins from Dartmouth College; Shelby Powersfrom East Carolina University; Leonora Shell from SciStarter; Jenni L.McDonald and Holly Cole from University of Exeter; Heidy Kikillus and LisaWoods from Victoria University of Wellington; and Hayley Tindle and PhilipRoetman from the University of South Australia.
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