Why can pigeons return to their homes no matter where they fly?

Audit expert: Zhao Liangyu

Associate Professor, School of Aeronautics and Astronautics, Beijing Institute of Technology

Ask a question: When you travel far away to a strange place, how do you get home? Most people will blurt out the answer: "Navigation!"

Indeed, with the vigorous development of satellite technology in my country, map navigation has now entered thousands of households, helping millions of children who could not tell the north from the south and were trapped on "maze-like" roads.

But how did people find their way home before the advent of navigation technology?

At first, the ancients relied on their inquiring mouths and their constantly running legs to slowly find their way back, but it took some time. Later, many reference tools appeared, the most important of which were maps and compasses. People used hand-drawn maps to assist navigation. These maps were based on landmarks, specific routes and direction instructions. Although the workmanship was crude, they were extremely useful.

Source: pexels

In addition, people can also determine the direction by observing the behavior of animals and plants. For example, the migration direction of migratory birds, the walking route of ants and the growth direction of trees can all provide useful navigation clues.

So how do animals find their way without modern navigational aids? And why can't humans?

01 How do animals navigate?

In early spring and late autumn, the sky often presents the spectacular sight of migratory birds; even on rainy days, bees can use the "8" dance to indicate the direction and location of the nectar source; no matter where pigeons fly, they can return to their homes... Animals are completely superior to humans in terms of identifying directions, and they can be said to be like the Eight Immortals crossing the sea, each showing their magical powers.

Source: pixabay

"Fiery Eyes and Golden Pupils" Visual Navigation System

Vision is one of the senses most commonly used by animals to determine direction. For example, migratory birds can use landmarks, the position of the sun, and constellations to determine the direction of flight. This is called the animal's star-moon navigation system, also known as celestial navigation.

Representative animals of this type of navigation include migratory birds, turtles, and insects. Migrating birds often use the positions of stars and constellations in the night sky to determine their direction; after hatching, turtles will look for the path formed by the reflection of the moon's light on the sea surface, and then crawl along this path to reach the ocean; some insects such as bees and ants observe the positions of the sun and the moon and use their movements to determine their own direction.

What about the well-known phenomenon of moths flying into flames? Is it just because moths like light? There were three main hypotheses about this question before: light navigation misleading, chemical signal interference, and genetic programming. Later, after long-term experiments and observations by scientists, the mystery of moths was finally solved: moths actually fly into flames based on the positioning of the moonlight.

When flying at night, moths and other insects rely on moonlight to determine direction . When moths see light, they mistake it for moonlight. Generally, moths can keep a fixed angle with the moon to fly in a certain direction.

However, because the light is close, the moth can only circle around the light, and the spiral flight makes the moth closer and closer to the flame until it is swallowed by the flame. So the moth flies into the fire because the fire source interferes with the moth's direction judgment, not because the moth flies directly into the flame.

Source: Poisonous Tongue Technology

In addition, some animals can determine direction by observing texture patterns, wind direction signs, and natural features on the ground.

"Listen to all directions" auditory navigation system

Some animals, especially those in the ocean, can use the propagation and reception of sound to determine direction. For example, whales can use the speed and direction of sound waves in seawater to navigate; some insects and birds can use hearing to perceive sounds on the ground and wind direction to determine direction.

Source: pixabay

Olfactory navigation system and magnetic field navigation system that can “see the smallest details”

Some animals, especially mammals, can determine the direction of a specific area by sniffing the air. For example, a dog can find a specific target by tracking the concentration and direction of the smell.

Some animals also have the ability to sense the direction of the Earth's magnetic field and navigate accordingly. For example, migratory birds may rely on the Earth's magnetic field to determine the direction of their flight.

02 The source of skills

How do animals acquire these abilities? Are they innate or acquired through training?

In fact, in nature, both exist.

It's natural

Some animals are born with the ability to distinguish directions. This is because they have a biological compass inside their bodies for navigation and orientation. For example, migratory birds navigate, turtles and some insects can also use geomagnetic induction to determine direction. These abilities are possessed by animals at the genetic level, and they interact with the environment through specific sensory organs in the nervous system.

Habit

Other animals may need to develop the ability to distinguish directions through later learning and experience. They determine directions by observing and learning visual, sound, olfactory and other sensory signals in the environment. The smells, sounds and images contained in the long-term living environment will leave an impression in the animal's mind.

Then, the animal will compare the information obtained from the outside world with the information in its mind, and find its way home as the two types of information get closer and closer. For example, young migratory birds need to follow the migration routes of adult migratory birds to learn and remember the correct direction, and insects can also find food or nesting directions by observing the position of the sun and wind direction.

03 How do humans identify directions?

Although humans are not born with the ability to recognize directions like most animals, we make up for our shortcomings in this area with our memory and analytical abilities that far exceed those of other animals.

Humans can remember many references in life and use them to determine directions. The sun rises in the east and sets in the west. The sun at noon always points exactly to the south. The North Star is located in the north at night. Houses generally face south. The leaves on the south side of trees are denser than those on the north side.

Even if you can't tell the directions in the city, everyone knows that "north is up, south is down, west is left, east is right". Therefore, when you face the sun with your right hand, your entire projection on the map will be "facing north, back to south, west is left, east is right", and you will naturally find your direction.