Toronto spent $31 million to fend off a raccoon invasion. Here's why cities can't get rid of them.

Raccoons, which can digest just about anything, are attracted to the huge amounts of garbage that build up in urban areas.
These highly intelligent, dexterous critters figure out ways of thwarting human efforts to stop them.
In 2016, Toronto spent $31 million to fend off a raccoon invasion, but the critters continued to swarm the city.

Following is a transcript of the video.

Narrator: In 2016, Toronto spent $31 million to fend off a raccoon invasion. The masked critters were everywhere, pooping on porches, stopping traffic, and infesting attics, and they're not just taking over Toronto. Reports of raccoon vandalism have plagued cities like Portland, Chicago, and New York City, and as raccoon-ridden cities know, we can't seem to stop them.

Between the 1930s and 1980s, the US raccoon population increased twentyfold, and it's still going strong. From 2014 to 2015, raccoon complaints in Brooklyn nearly doubled, so how are these masked bandits making it in big cities?

Well, for starters, they can digest just about anything from fish and acorns in the forest to dog food and pizza on the street, and just like humans, raccoons usually prefer the pizza, which is why they flock from woodland to city in the first place.

In Brooklyn, for example, captured raccoons sometimes get relocated to Prospect Park and nearby forests, but wildlife biologists report they often head right back to the dumpster-packed city streets.

It's just about impossible to stop them, as Toronto discovered after it spend millions on raccoon-proof waste bins. Unlike traditional bins, the lids had special gravity locks, which open when a garbage truck arm turns the bin upside down. The idea was that if you cut off their major food source, they would skip town, but that didn't happen. In fact, one year later, a wildlife-control business reported that raccoon-related work had doubled.

Finally, a clever raccoon was caught on camera jailbreaking the new bin. How did she outwit an entire city? Well, study after study has revealed that raccoons are considerably smarter than your average medium-sized critter. Turns out raccoon brains have more neurons packed into their brains than other animals of the same size.

In fact, they have the same neuron density as primates, who are notoriously smart, and their clever brains help explain why raccoons can open complex locks, solve puzzles with ease, and even come up with solutions to problems that scientists didn't think of. Add to that their ultrasensitive hands, er, paws, which have four times as many sensory receptors as their feet. This helps them to feel subtle textures like special trashcan lids in Toronto and even open locks without looking.

And unfortunately for us, driving them away is a fool's errand. Studies show that after mass removal, populations tend to rebound to their previous levels in a year. After all, females can start giving birth at just 1 year old and can have as many as eight kits in a single year. This quick breeding is also why experts say mass cullings aren't a long-term solution.

And while they're awfully cute, the damage they can cause is not. When raccoons nest in buildings, they can destroy insulation, chew up wires, and tear holes through walls, and it can cost you hundreds or even thousands of dollars to repair that kind of damage. One raccoon was even caught destroying over $3,000 worth of artwork, and just removing them can cost $300 to $500 a pop.

Plus, the poop they leave behind can contain roundworms and other parasites, which can enter your lungs when you breathe or get tracked into your home by your pets. Even worse, raccoons can transmit diseases like canine distemper and, in rare cases, rabies.

So it's understandable that cities are trying to find some way, any way, to manage them.

Man on broadcast: Can't do a thing about it, just chase them off. They come back.

Narrator: If nothing else, it's a lesson learned. We may have built the cities, but we don't necessarily rule them.

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