China’s first batch of six drug-sniffing squirrels have been deployed. Can they take on this important task?

We know that there are drug detection dogs, but have you ever heard of "drug detection squirrels"? As the name suggests, they are trained squirrels to assist the police in discovering and detecting drugs.

Earlier, the Police Dog Brigade of the Criminal Police Brigade of the Public Security Bureau of Hechuan District, Chongqing City learned that under the technical guidance of the Police Dog Brigade, the first batch of six drug-detecting squirrels in China were successfully trained. Breeding drug-detecting squirrels is a sub-project of the National Key R&D Project "Development of Breeding and Training Methods and Supporting Equipment for New Drug-Detecting Animals" "Development of Breeding and Training Methods and Supporting Equipment for Drug-Detecting Rats" and has been completed. The squirrel species selected is the devil squirrel. The first batch of six drug-detecting squirrels were trained and have been certified by relevant scientific research institutions.

Is Squirrel Reliable in Catching Drugs?

What do you think of this? Anyway, I saw it on my phone. From the perspective of a "beast" researcher, I think there is a scientific reason to use squirrels to fight drugs.

The devil squirrel is actually the Eurasian red squirrel. Many people may question: the experts are talking nonsense again, it is obviously a gray squirrel, but you insist it is a red squirrel. There are more than a dozen subspecies of Eurasian red squirrels in the world. The subspecies in China are not red, but the European ones are red. In recent years, the red subspecies of Eurasian red squirrels have appeared in the Altay region of Xinjiang, China, which is likely to have spread from Europe. Many times we cannot judge by the name, for example, there is no wife in the wife cake.

So is the squirrel's drug-hunting method reliable? I think it has some scientific validity.

First , as rodents, squirrels have an extremely sensitive sense of smell and can distinguish a variety of odors. Squirrels can use their sense of smell to distinguish whether hazelnuts are rotten. Even if they are not rotten, if they are hollow inside, squirrels can smell it. If I had this nose, I wouldn't be afraid of being cheated when I go to the supermarket to buy nuts.

Second , squirrels are small in size and can be used to search for drugs in complex environments such as logistics warehouses and express delivery stations, or at high altitudes. These are places where police dogs are useless, which is the value and significance of training squirrels to detect drugs.

However, squirrels also have their own shortcomings. In terms of animal intelligence, squirrels are definitely not as good as dogs, so whether and how to cooperate in the later training are certain problems. Moreover, there is still a certain gap between the effect in the experiment and the actual situation, and the data in the laboratory can only be used for reference. In the end, whether a squirrel can become a qualified anti-drug squirrel and whether it can hold a certificate and enjoy the establishment still needs practice and time to test.

Another thing is that squirrels have the characteristic of burying food, and they will bury it in a scattered manner. In the future, if they "do not change their nature" and take drugs as their food, then they will be breaking the law knowingly and be suspected of smuggling!

Squirrel planting trees

Squirrels do have the habit of storing things. Their food storage can be roughly divided into two types, one is dispersed storage and the other is centralized storage.

Dispersed storage is the process of placing a large number of plant seeds in multiple storage points, with each storage point storing one or several seeds. The storage points are generally close to the ground surface. When conditions are right, the seeds may germinate into seedlings. This type of storage has a spreading effect on plant seeds.

Centralized storage is to place a large number of plant seeds in one place, such as a nest, which is generally of a certain depth. The storage method used depends on the type of squirrel, the characteristics of the seeds and the surrounding environment. Most squirrels only use one storage method, and a few species use both methods. For example, red squirrels use centralized storage of cones in coniferous forests in North America, and dispersed storage of acorns in broad-leaved forests.

However, although squirrels can use their sense of smell to help themselves find their own scattered buried food, this is not a very ideal effect. Scientific research has shown that gray squirrels, American red foxes and red squirrels may rely on spatial memory to retrieve stored food. Scientists found in field experiments that gray squirrels can quickly find their own buried seeds, but it is difficult to find the seeds buried by the experimenters. In the forest, red squirrels can be observed to climb directly onto pine trees that hide dried mushrooms. The dried mushrooms are hanging in the tree canopy, and the red squirrels on the ground can neither see nor smell the smell of the mushrooms. The only possible explanation is that the red squirrels remember the location where the mushrooms are stored.

Squirrels store a lot of seeds, but the retrieval rate is also high. For example, 63% to 80% of the seeds stored by chipmunks are retrieved. Despite this, many storage sites are still forgotten or left behind, and then germinate.

The microenvironment of the storage point has a crucial influence on whether the seeds can germinate. Squirrels that scatter store seeds bury a large number of seeds in scattered areas below the surface and under the litter layer in the forest. Such storage point habitats are often very suitable for seed germination. North American chipmunks bury most of their seeds at a depth of 7 to 22 mm underground, which is very suitable for seed germination. Research in Hokkaido, Japan shows that the depth of squirrels burying red pine seeds is mostly 2.5 to 3.5 cm, and this depth is considered to be conducive to the germination of pine seeds.

Squirrels cache food first and foremost to help seeds escape predation and avoid competition.

Squirrels' scattered storage effectively reduces the density of seeds and hides them, which helps the seeds survive. If Korean pine seeds fall under the mother tree, they will all be eaten by squirrels, and squirrels' scattered storage can effectively preserve many seeds until germination.

Secondly, squirrels' food storage can expand the distribution of plant populations. Although the distance that squirrels carry is usually only a few dozen meters, the place of spread is often a new distribution area.

Moreover, squirrels’ seed dispersal is different from birds’. Squirrels’ warehousing dispersal is directional, not only taking seeds away from the source, but also bringing them to microhabitats where they can germinate; bird dispersal is mostly random dispersal of seeds with feces. However, bird seed dispersal is a mutually beneficial symbiotic relationship between animals and plants. Plants use the pulp in their fruits to attract birds to eat. The birds are rewarded and also help spread the plant seeds. The warehousing dispersal represented by squirrels is different. Squirrels directly feed on seeds, so they are both seed predators and disseminators. The relationship between squirrels and seeds is rather contradictory. Plants must rely on them for dispersal, but also defend against their predation. It is not a simple mutually beneficial symbiotic relationship.

Many missed storage sites had saplings growing in the spring of the following year, and the squirrels only realized that there had been "food" buried there, and they had inadvertently become voluntary seedling nurseries. Their behavior was of great benefit to the spread of seeds.

Therefore, the fact that squirrels store food does not prove that they have a strong sense of smell, but the fact that they can "bury drugs" does prove it.

This article is a work supported by Science Popularization China Starry Sky Project

Author: Zhao Xumao

Reviewer: Huang Chengming (Researcher, Institute of Zoology, Chinese Academy of Sciences)

Produced by: China Association for Science and Technology Department of Science Popularization

Producer: China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.