Cams expose mysteries of feline prowling
Cape Town - ‘”acavity’s a Mystery Cat: he’s called the Hidden Paw”, poet TS Eliot wrote in his famous children’s poem of the same name.
Now, a postgraduate thesis at UCT has helped shed a little bit of the mystery about Macavity, Mungojerrie, Rumpleteazer and all the other domestic felines of the world – but no one is suggesting their activities constitute actual crimes, even though kidnapping and death feature quite prominently in their story.
The author of this serious scientific thesis is Frances Morling, 26, who submitted it as part of the requirements for her Master’s degree in conservation biology through the Percy FitzPatrick Institute of African Ornithology.
Her topic was predation by domestic cats, and her subjects were 13 pet moggies living happily in Newlands – about half in homes in “deep suburbia” and the other half living on the urban edge that backs directly on to the Table Mountain National Park – who wore “kitty-cams” or miniature cameras on their collars to record what prey they caught and how they spent their time.
She explains that most research on this important topic has been carried out in the developed world – Australia, New Zealand, the UK, the US and Canada “where there’s not a whole lot of wildlife left, compared to here in Africa”.
Just two studies on domestic cats have been done previously in Africa, both also through the FitzPatrick Institute and both supervised by Morling’s co-supervisor, Dr Rob Simmons.
One of the latest overseas studies, from Virginia in the US, involved the use of the kitty-cams, and this was very significant because all previous studies on the impact of domestic cats had used data derived from only what wildlife the animals actually brought home. And this study found that they only bring back one quarter of what they catch, she explains.
“So is that true more universally? If so, it means that the other studies have all been massively underestimating what cats catch. That’s what I primarily set out to determine.”
Her research took place over a five-week period last summer.
First, she applied the same method as the previous two UCT studies: a questionnaire survey in which the owners were asked to record all prey items returned by their cats. According to this data, 43 prey items were returned: 18 small mammals, 13 invertebrates, five reptiles, four amphibians and three birds.
“Combining this data with the two similar surveys, I estimated that a total of 118 cats each caught an average of 0.04 prey items per day.”
Then, 10 of her 13 cats were monitored for three weeks while wearing kitty-cams. Morling collected an average of 39 hours of footage per cat, making a total of 394 hours – nearly 16-and-a-half days – of both diurnal (during the day) and nocturnal footage.
She found that reptiles constituted the majority of prey recorded on the kitty-cams – in particular the marbled leaf-toed gecko – followed by invertebrates, small mammals and amphibians. Of 23 prey items recorded, only five were returned to households; 15 were eaten in situ, and three were abandoned on site.
She then used these findings on the proportion of prey not brought home (78 percent) to produce a correction factor (4.55) for those studies that had only involved counting prey brought home.
This increased the estimated number of prey items killed by cats within the greater Cape Town area each year from an estimated 5.7 million in the previous studies to 25.8 million prey items, within a statistical range of 18 to 33 million.
“And the really interesting thing is that cats here also bring back less than a quarter of what they catch – the results were incredibly similar to the 2013 study in the US, which is really interesting and really quite exciting,” says Morling.
“It suggests that introduced domestic cats are having a much greater impact on prey populations than previously estimated.”
How did Morling find the cats for her study and did she encounter any hostility from cat owners, as had the two other UCT researchers?
“I was really lucky because Newlands is a very friendly neighbourhood, and I got access to the neighbourhood mailing list to send out a call for volunteers – that’s how I found most of them,” she responds.
“But I was also quite specific about the kind of cat I wanted to use, so I ended up looking for my last four or five volunteers by going door to door.”
Unlike her earlier counterparts, she didn’t encounter any antagonism from people thinking such research might be the basis for an attempt to get cats banned.
“I’m not sure why I didn’t get that reaction in Newlands – everyone was very friendly, I was invited in for a cup of tea, it was lovely. I don’t know whether it had anything to do with the fact that I’m a cat lover myself, and maybe I came across a little bit less scientific.”
Her own two cats, Garfield and Ginny, live with her parents in Bergvliet, and they were her “guinea pigs”.
“They were my test subjects for cameras and collars and harnesses and all sorts of things, although I didn’t actually use them for the study.
“Collars they had no problem with at all, which I was really surprised about; nor with the cameras. So I could enthusiastically and confidently tell people that there weren’t going to be any problems, and in fact I didn’t have anyone whose cats had a problem with the cameras.”
She had also been hoping to track her subjects with GPS devices but that wasn’t possible because it would have required a harness. “And cats hate harnesses – they just lie down until you take them off. It’s just too much weight.”
The cameras were “a bit of a nightmare” and she had lots of technical problems with them, she adds.
“They’ve never been used on this sort of scale – they got dipped in swimming pools (when some cats drank) and got lost and all sorts of things. They’re not ideally designed.”
Now, well designed or not, what use could Macavity and his cronies have made of kitty-cams, had they been around in the 1930s? Some dastardly feline depravities, no doubt. - Sunday Argus