Arms race in the war on raccoons

“Madrid declares war on plague of raccoon and parrot invaders”
The Guardian (2013, July 22)

“Toronto wages war on Raccoon Nation”
The Canadian Press (2015, May 3)

Many places have declared the war on raccoons in recent years. But is this war only making them stronger?

Why declare war on racoons?

The raccoon (Procyon lotor) originates from North America, where they mostly live in forests and near water bodies, but they can also be found in mountains, marshes, and urban areas. Later, the North American raccoon became part of the fauna in Europe and Asia due to accidental releases from fur farms and private holdings. Raccoons are not picky about where they live, they can migrate extensively and eat nearly anything. Atop of that they lack many natural predators — no wonder so many places are struggling with an abundance of raccoons. 

Raccoons have a talent for finding and handling their food, as they use their vision and touch to identify objects, which they can grasp and manipulate (Iwaniuk & Whishaw, 1999). Their paw mobility, amazing climbing ability, and cognitive functions make raccoons very capable of accessing many food sources — ours included. This means that raccoons love our towns and cities.

And these furry new citizens aren’t well-behaved. For example, “Raccoon plunges parts of Toronto into darkness mishap at power utility”, reads the headline of an article in The Guardian (2024, February 2), about how 7.000 people in downtown Toronto lost power because a lone raccoon got to the ‘equipment’. Other problems include: raccoons damaging native ecosystems, such as feasting on endangered salamanders; causing agriculture losses; transmitting diseases such as rabies; and damaging property such as thousand-year-old Buddhist temples in Japan (Suzuki & Ikeda, 2020). Not only that, they are also mischievous about it. They show up at baseball games, break into banks, and steal and eat food while holding eye contact with you. Altogether, it has led to ‘Raccoon Wars’ around the world.

The Arms Race

Cities with raccoon problems respond by setting traps, which turned out to have little effect because raccoons dodge and break the traps. Another method that was tried was the use of raccoon-proof bins, since raccoons thrive in cities because of the abundant supply of food. This is especially true because of people handing them food and leaving it in easily accessible green bins. In an effort to stop (or at least decrease) the raccoon infestation, the city of Toronto invested $31 million to engineer a raccoon-proof bin that was tougher and had a hand-turned locking mechanism, hopefully preventing raccoons from getting in.

It took them a couple of days to figure the bins out:

The puzzles we create for the raccoons to access ‘their’ food increase the benefit of learning and might put a selective pressure on the populations for enhanced learning. This means that the more we try to lock away our food, the smarter the raccoons might get. A recent study by Lazure and Weladji (2024) tested the learning ability of wild raccoons by giving them cognitive tasks to complete. By repeating these tasks for multiple nights, they saw that the raccoons did learn. To make matters worse, the raccoons from places with more anthropogenic food sources tended to improve their success rates, while the performance of raccoons in preservation zones decreased. This means that we have already trained the raccoons in solving foraging-related puzzles, and they even retained the learned solutions for almost a year — meaning that the urban raccoons have a long-term memory of how to solve our puzzles. The researchers also found that the more difficult puzzles were solved less, and the learning took longer. 

That means that if we make bins more difficult to get into, the raccoons eventually will get in until we make the bins even more difficult. We will eventually reach the point where even we cannot get into them anymore. So if you ask me, the raccoons have already won this war.

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References

Iwaniuk, A. N., & Whishaw, I. Q. (1999). How skilled are the skilled limb movements of the raccoon (Procyon lotor)?. Behavioural brain research, 99(1), 35-44.

Lazure, L., & Weladji, R. B. (2024). Methods to mitigate human–wildlife conflicts involving common mesopredators: a meta‐analysis. The Journal of Wildlife Management, 88(2), e22526.

Suzuki, T., & Ikeda, T. (2020). Invasive raccoon management systems and challenges in regions with active control. BMC ecology, 20, 1-13.

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Featured photo: © Martin Kaehrle, some rights reserved (CC-BY)