When it comes to fighting New York’s notoriously bold city rats, setting the cats on them might not be as good a solution as you’d expect.
For the first time, researchers have quantified the effects of feral cats in an area overrun with large rodents, tracking the interactions between predator and prey at a New York City waste recycling center.
And, they found the cats weren’t very effective at curbing the rat population.
Over the course of 79 days, the cats only made three kill attempts – one of which ended unsuccessfully because the cat lost interest in its target.
When it comes to fighting New York’s notoriously bold city rats, setting the cats on them might not be as good a solution as you’d expect. File photo
‘New Yorkers often boats their rats “aren’t afraid of anything” and are the “size of a cat,” Parsons said.
‘Yet cats are commonly released to control this relatively large, defensive and potentially dangerous prey.’
The new research provides evidence that there are few benefits to releasing cats into the urban ecosystem.
If anything, the researchers say doing so will do more harm than good, as cats prefer smaller prey such as birds and can be a threat to local wildlife.
Rats, on the other hand, are larger and much better able to defend themselves.
‘Like any prey, rats overestimate the risks of predation,’ said lead researcher Dr. Michael H. Parsons.
‘In the presence of cats, they adjust their behaviour to make themselves less apparent and spend more time in burrows.
‘This raises questions about whether releasing cats in the city to control rats is worth the risks cats pose to wildlife.’
Researchers studying a colony of over 100 rats in an NYC waste center were presented with an opportunity when a group of feral cats invaded the space as well.
The rats had all been microchipped, and once the cats moved in, the researchers installed motion-capture cameras.
This allowed them to observe the interactions between the two in a natural setting.
‘Until now, no one has provided good data on the number of city rats killed by cats,’ said co-author Michael A Deutsch, from Arrow Exterminating Company Inc.
‘But the data have been very clear as to the effect of cats on native wildlife.’
For the first time, researchers have quantified the effects of feral cats in an area overrun with large rodents, tracking the interactions between predator and prey at a New York City waste recycling center. File photo
‘We wanted to know whether the number of cats present would influence the number of rats observed, and vice versa,’ Parsons said.
‘We were also interested whether the presence of cats had any effect on eight common rat behaviors or their direction of movement.’
Over 79 days, the researchers captured 306 videos, revealing as many as three cats active beside the rats every day.
But in all this time, there were only 20 stalking events, and two successful kills – both of which took place when the cats encountered a rat in hiding.
The rats did, however, spend less time out in the open when the cats were around.
‘The presence of cats resulted in fewer rat sightings on the same or following day, while the presence of humans did not affect rat sightings,’ says Parsons.
‘We already knew the average weight of the rats was 330g, much more than a typical 15g bird or 30g mouse.
‘As such, we expected a low predation rate on the rats – and our study confirmed this.’
According to the researchers, the findings don’t mean cats won’t ever hunt rats if given the opportunity.
But, conditions must be right or they’re more likely to go for an easier target.
‘The cat must be hungry, have no alternative less-risky food source, and usually needs the element of surprise,’ Deutsch said.
‘People see fewer rats and assume it’s because the cats have killed them – whereas it’s actually due to the rats changing their behaviour,’ Parsons said.
‘The results of our study suggests the benefits of releasing cats are far outweighed by the risks to wildlife.’