In one of the unintended consequences of the world’s lockdown and widespread closures of central business districts, rat populations have to look for new sources of food – in the suburbs.
City centre garbage and leftover meals from restaurants and takeaway outlets has long provided rats with a steady source of food.
But in the last few months the coronavirus has changed all that and rat populations are now seeking greener pastures, particularly with the Southern Hemisphere winter arriving in force.
Speaking to Guardian Australia, Sydney rat-catcher Geoff Milton said calls about suburban rats have risen 30% compared with the same time last year.
“They have moved into the suburbs, closer to residential [areas],” he said. “We are having a big spike in residential rodent control.
“It’s got colder quicker this year as well. It is coming on to winter where they need somewhere warm to sleep. They usually get into roof voids in people’s houses, because they can climb up brick walls or they can leap from overhanging trees above peoples’ houses.”
The rats have to eat immediately and are food stressed
Prof Peter Banks, a rodent expert from the University of Sydney, told Guardian Australia he agreed with Milton.
“We locked down and stopped using the city and closed restaurants quite rapidly, and that was quite long ago. The rats have to eat immediately, so this [movement to the suburbs] would have happened days after, because the rats are so food stressed.”
He added: “They are so dependent on our garbage and our spilt food. The rats we have in the centre of Sydney are the same species as in New York … They are wholly dependent on us. If they produce babies they can’t support, they kill them. Or one of their relatives comes in and kills them.”
Watch a video from CBC News in the US here.
But don’t expect a plague of rats
But both men are in agreement that Sydneysiders won’t wake up one morning to see a locust-like plague of rats sweeping across the horizon, devouring all before them.
Winter usually creates a natural culling of the rat populations and others will likely have died fairly soon after their city-centre food supply came to a sudden end.
So there is a small, but noticeable increase in the suburban population. But many will likely also head back to their CBD happy hunting grounds once life there returns to normal.
UK pest technicians warn of ‘unintended consequences’
It’s something that’s happening around the world. In April, the BBC reported on a warning issued by the National Pest Technicians Association that “the closure of schools, pubs, restaurants, hotels, tourist attractions and other public places to enforce social distancing will have unintended consequences”.
The association added that, if there is food available, pest populations could thrive in empty buildings and become emboldened by the absence of people – or they will go out in search of food.
In New York, renowned urban rodentologist Dr Robert Corrigan Hungry said rats “can wander quite a distance and end up in a different neighbourhood completely that had no rats prior”.
They are “formidable mammals” very good at sniffing out sources of food and their powerful teeth can make short work of barriers like doors, plastics or fabrics, he told the BBC. “They’re global, they’re everywhere, and they didn’t get to be completely global if they weren’t very skilled at being masters of adaptation.”