1. Are Raccoons Really Washing Their Hands?
The name raccoon comes from the fact that putting front paws in water to search for prey looks like hand-washing. According to materials from Maruyama Zoo in Sapporo, this appearance is the origin of the name [1].
In reality, it is a strong theory that they are not washing. In the wild, raccoons move their front paws as if feeling around near water edges to find aquatic creatures. Captive raccoons sometimes soak food in water, but this is believed to be a leftover behavior from eating on riverbanks, not an attempt to remove dirt [6].
However, why this specific action remains in captivity is not fully understood. The name was given based on appearance, while the reason for the movement is a separate issue [1].
2. What Do Raccoons Eat? An Omnivore's Wide Diet
The short answer to what raccoons eat is "almost anything." Maruyama Zoo materials explain that raccoons are omnivores and eat a wide variety of things, including insects, fruits, and small mammals [1].
Materials from Chiba Prefecture also state that they eat everything from small mammals and birds to vegetables, fruits, and grains [2]. Wildlife resources from Fairfax County in the US list a natural diet including fruits, berries, plants, grains, nuts, insects, fish, frogs, turtles, small mammals, birds, and eggs [5].
As a rough guide to their food breakdown, English Wikipedia cites one estimate where invertebrates like bugs make up about 40%, plants 33%, and vertebrates 27% [6]. In this estimate, the total is 100%. However, these are estimates that change depending on the location and time of the survey, and they are not specific figures for Japan.
3. Why Raccoon Paws Work Like Eyes Underwater
Raccoons are primarily nocturnal animals. According to Sakai City materials, they have sharp claws and dexterous hands [4]. In water, Wikipedia states that the sense of touch in their front paws is more important than their eyes, so they use their paws to search for prey [6].
According to English Wikipedia, the thin layer of keratin covering the surface of a raccoon's paw softens when wet. Rubbing the paws underwater increases tactile sensitivity. It is also said that about two-thirds of the somatosensory cortex in the brain is dedicated to processing touch [6]. Note that this information comes from secondary sources and has not been verified by primary research papers.
With wet paws, their sense of touch becomes more sensitive, allowing them to find small animals underwater with their fingertips. This explains why the movement looks like "washing" but is actually using hands to "see" food [6]. These paws are used not only at water's edge but also near human homes.
4. How Raccoon Diets Change Near Human Homes
Fairfax County materials divide the raccoon diet into two categories: "natural food" like fruits and fish, and "human-impacted food," which includes pet food, trash, and birdseed [5].
Japanese local governments convey similar information. Saitama Prefecture materials state that raccoons are omnivores and eat anything, including pet food, fruits, and discarded crops. They call for caution against feeding animals in daily life [3].
Chiba Prefecture materials note damage to crops such as corn, watermelons, and grapes [2]. To a raccoon, field crops are simply "sweet and nutritious fruits or grains." For the animal, these are places where food is found, but for people, they represent damage. Materials from various prefectures indicate that not feeding wild animals helps prevent increased damage [3].
5. Why Raccoons Were Brought to Japan and Became Wild
Raccoons are native to North America, and they were brought to Japan by people as pets. Hokkaido Prefecture materials explain that individuals imported as pets escaped or were abandoned, leading them to become wild [7].
In Hokkaido, it is said that the beginning of this process occurred in 1979, when about 10 raccoons kept in Eniwa City escaped and settled in dairy farming areas [7]. A broad diet is thought to lead to easier expansion of their habitat. This also affects the animals they eat.
Chiba Prefecture materials list damage to ecosystems, including predation on native amphibians and reptiles like the Tokyo salamander and Japanese pond turtle, in addition to crops like corn and watermelon [2]. The movement of searching underwater with paws is part of life in their original habitat, but for small creatures in Japanese waters, it is a new event.
6. Try It Yourself: Testing a Paw's Sense of Touch in Water
You can try this today: Put warm water in a washbasin and submerge marbles or sponges. Close your eyes and feel around with your hand to guess what is there. You might find that shapes are easier to understand with a wet hand than a dry one.
SAFETY NOTE: Please do this with an adult so you do not spill water.
If you want to read more, look for the "Raccoon" page on your prefecture's website. It contains explanations of food and damage, along with cautions about feeding [2] [3].
The remaining question is: Why does the action of soaking food in water remain in captivity? There is no definitive answer to this question yet.