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Camera traps and webcams have revolutionised wildlife research, allowing views into the secret lives of some of the planet’s most elusive creatures. They’ve also thrown light on the goings-on of a more familiar, yet still mysterious beast – the domestic cat.
Studies such as the The National Geographic and University of Georgia Kitty Cams Project, which attached portable webcams to 60 free-ranging pet cats' collars, have effectively answered the question that has long tantalised cat owners:
Where does Felix go when he slips under the garden gate, and what does he get up to? (And what’s wrong with the lovely home I’ve provided for him?)
That lazy, two-timing, risk-loving tail-chaser
Well, Felix does a fair bit of lazing about, maybe under a car or on a rooftop in the sun. Cats spend about 16 hours out of 24 resting. Not that there’s any shame in that: lions spend 20 hours a day lying around, conserving energy for the burst of speed they need to bring down prey.
Felix may also be two-timing you, visiting your neighbours for snacks and snuggles. Not necessarily because you’re depriving him of either commodity, but just because he can.
More seriously, he probably takes risks: crossing roads; facing off with strange dogs, cats and wildlife (not to mention dodgy humans); exploring drains and crawlspaces where he might get trapped; and sampling substances you certainly didn’t give him (like stormwater runoff and the old potato peels I once observed my own well-fed cat grazing on in the gutter). Male cats are more prone to risky behavior than females, as are frisky youngsters.
Even more seriously: Felix may well be killing things. Lots of things.
Natural born killers
We knew this, even the most sentimental cat ladies and gents among us. Some of us are even a little proud of Felix or Missy’s hunting prowess. But we hadn’t fully realised the amount and variety of animals hunted, simply because we couldn't see most of the trophies – till now.
The Kitty Cams Project found that 44% of their feline subjects hunted, bagging on average two prey animals a week. Of these, they left 49% where they’d caught them; ate 28%; and brought 23% home, to no doubt less than grateful humans. Male and female cats spent about the same amount of time hunting, and both hunted more in the warmer months and less as they started getting elderly.
Not just a cat-and-mouse game
Unfortunately, cats don’t limit their hunting to rounding up rodent pests, the job humans domesticated them for in the first place. Their haul worldwide includes all manner of small creatures, indigenous wildlife species too. Rats and mice don’t even top the list. The Kitty Cam cats’ most popular prey were Carolina anoles (small lizards).
Two recent student projects on cat predation in Cape Town around Table Mountain and the suburb of Glencairn, which is adjacent to a wetland, found that prey included a range of wild vertebrates -- shrews, golden moles, geckos, snakes and sunbirds, among others.
Dr Rob Simmons of the Percy Fitzpatrick Institute, University of Cape Town, who supervised the research, says that local cat owners report even such exotic prey as scorpions and baboon spiders, and one innovative hunter who likes to sit on the roof and nab bats as they flit past.
Cats’ hunting trips generate some alarming statistics. A study published last month in Nature Communications estimates that free-ranging cats (owned pets and feral cats) in the USA kill 1.4-3.7 billion birds and 6.9–20.7 billion mammals annually – prompting the researchers to speculate that cats are likely the single greatest source of anthropogenic (i.e. human-linked) mortality for US birds and mammals.
Feral cats are thought to cause most of this carnage, but Simmons points out that in some parts of the world, such as South Africa, owned free-ranging cats may be responsible for a higher portion of wildlife mortality. Although owned cats aren’t driven to hunt by hunger, they often have a higher density than their feral counterparts. In Glencairn for example, the density of owned domestic cats is a staggering 300 per square kilometre.
The US wildlife mortality figures may sound exaggerated, but Simmons says that domestic cat predation has been underestimated until recently:
“Scientists knew domestic cat hunting was a significant threat to wildlife, but the Kitty Cams study, for instance, suggests that the predation rate is four-fold greater than had been thought.
"The Cape Town research indicates that cats in this area alone are killing between 3.9 million and 5.9 million animals each year – and I would say that’s a conservative estimate.”
Cats living on the urban edge i.e. where the built urban environment starts to merge into natural vegetation or rural areas, hunt further from home and have a higher kill rate.
No bad cats, just short-sighted humans
Before we start putting the blame on cats, though, it’s important to remember that, as is often the case with 21st century environmental problems, it’s really our fault. Most of the species we’ve tamed for food or companionship have multiplied prodigiously along with us, into the millions or billions.
It's because we domesticated cats 10 000 years ago and then fell in love with them that there are now over 500 million worldwide, many of which are strays with no choice but to fend for themselves, tooth and claw.
Simmons feels that we are seriously lagging behind countries such as the USA, UK, Australia and New Zealand in terms of managing the cat predation problem: these countries regulate cat ownership in several sensitive areas, for example residential areas bordering reserves.
Similarly, on our urban edges, such as where residential Cape Town borders on the Table Mountain National Park, we should be looking into reasonable restrictions on cat ownership and roaming.
Protecting wildlife - and protecting your cat
It's clear cats pose a biodiversity threat, but many cat owners want their pets to have freedom of movement and feel that an indoor existence is unnatural and lacks stimulation.
However we should consider that most animal protection societies, and many vets, argue that outdoor cats lead a far more perilous existence than their indoor counterparts. In addition to the risks mentioned earlier, they're also exposed to infectious diseases and parasites.
Fortunately there are several simple measures that can significantly reduce both the impact of predation and risk to cats, without banishing them indoors entirely:
- Put a bell on your cat's collar. Simmons says this has been shown to reduce the kill rate by 50-60%. Also recommended is the CatBib, which interferes with their ability to pounce on prey, but not with other normal activities.
- Feed your cat regularly
- Keep your cat in at night
- Keep your cat confined to your garden. Garden fauna won't be safe of course, but the impact should be considerably reduced.
- Schedule regular play sessions with your feline companions. This helps keep them entertained and exercised (though it probably hones hunting reflexes too), and may encourage them to stay closer to home.
- Apparently it’s possible to train most cats to walk with a harness and leash from kittenhood, although this cat owner is dubious.
Not all cats require these measures; some are fearsome hunters and others are mellow fluffballs; some need stricter reining in because they live on nature reserve borders while others are inner-city cats who seldom encounter wildlife. Older outdoor cats are also less of a worry: they venture out less and Simmons says most of the Cape Town study cats had stopped hunting by age 13.
If you want to do some cat sleuthing of your own, you can buy a pet cam for about $40 plus shipping. For a taste what to expect, check out the Kitty Cam kitties' great stills and videos.
References
Loss, Will and Mara. 2013. The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications.
The UCT cat predation studies were conducted by students Sharon George and Koebraa Peters.
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