The Paradox of “Pests”

by Lisa Barrett


Read about the cognition of “nuisance” species involved in human-wildlife conflict in my lab’s new review paper. (photos: H.B.Evich; L.P.Barrett; F.Brotcorne; J.Sartore; iStock)
Link to article:

Have you ever had to swerve to avoid hitting a wild animal on the road, or been involved in a “war” with trash-invading raccoons in your neighborhood? Have you shuddered at the sight of a rat in the subway, or chased away a seagull eyeing your sandwich on the beach? Many people classify these animals as “nuisance” species or “pest” animals. Less familiar to you may be nuisance animals such as dolphins that have learned to steal fish from fishermen, macaques that barter with tourists’ stolen sunglasses in exchange for food, and elephants that disable electric fencing with trees in order to raid a farmer’s crops. Instances of human-wildlife conflict like these are not rare, and they may result in death or injury for animals and property damage or hardship for humans (and in some cases, injury and death).

When you think of these nuisance species, you probably don’t think about their behavior and cognition. But interestingly, there may be a lot going on there. Animals are using cognitive abilities such as innovation, learning, memory, and behavioral flexibility to thrive alongside humans (Barrett et al., 2018). You can even see differences in these abilities between urban and rural populations of the same species. For example, many urban individuals habituate to humans more readily and demonstrate higher rates of innovation than their rural conspecifics.

One classic example of innovation aiding animals’ success in a human-dominated area is milk bottle opening by great tits. Squirrels finding their way into your backyard bird feeders is another great example of innovation at work in a nuisance species. Kea are large parrots endemic to New Zealand that are attracted to novelty and are notorious for destroying car tires and getting into backpacks. As a result, they are targeted by humans who are annoyed by their antics; this has contributed–at least in part–to their endangered status. Animals that are known for their flexible use of food sources and habitat, such as raccoons, also do well in human-dominated and urban areas but are targeted by humans as a result. This paradox—that pest animals use cognition to succeed in human environments but are more likely to come into contact with humans—has caused the human-wildlife conflict with which we are familiar.

It is interesting to consider how we can harness these cognitive abilities to mitigate conflict with wildlife. We could devise innovative solutions, like setting up automated feeders that reward animals for disposing litter into them (Klein, 2007), or training captive animals of social species to dissuade dangerous behavior (e.g., crop raiding) characteristic of their wild counterparts (Sukumar, 2003).

Do rats navigate and remember the subway system and alleyways in cities? If so, how do they do that? Could raccoons learn which night is “trash night”? Do elephants learn to raid crops from each other? Will kea birds continue to be attracted to novel items even though this trait could result in them being shot and killed by humans? Many questions remain to be explored empirically. However, the next time you see a pest, perhaps you can appreciate the cognition involved in their success. After all, not all species can survive when faced with anthropogenic disturbance, so “smarty pests” are, in a certain sense, remarkable.



Barrett, L.P., Stanton, L., and Benson-Amram, S. (2018). The cognition of ‘nuisance’ species. Animal Behaviour. DOI 10.1016/j.anbehav.2018.05.005.

Klein, J. (2007). A vending machine for crows (Master’s thesis). New York, NY: New York University.

Sukumar, R. (2003). The living elephants: Evolutionary ecology, behavior, and conservation. New York, NY: Oxford University Press.


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