How do animals navigate the night?
Discover the different methods animals use to see in the dark
A human’s conscious life is largely dictated by the position of the Sun. We have learned to rise with it and sleep shortly after it dips below the horizon. Why do we do this? It’s because our species depends on visible light to navigate through each day. While we are walking to work in the morning sunshine or relaxing in the evening as the light begins to fade, other animals are hidden away in their dens and burrows. They are waiting for darkness to fall. When it does, a new community of creatures comes out to play.
These masters of the night carry adaptations that give them an advantage during the colder and darker hours. If you were to intrude on nocturnal life with the light of a torch, you’d likely see a variety of wide, glossy eyes staring back at you. These big eyes give an advantage to animals by allowing them to utilise every glimmer of light available, to observe the activity of the night.
Some other animals avoid the daytime as the lack of illumination gives them no disadvantage at all. They are blind to light anyway but rely on other, heightened senses. With ways of feeling, smelling and hearing nocturnal homes and neighbours, read on to discover some of these night-navigating superpowers.
For snakes that hunt during the darkest hours of the night, spotting a tiny, scurrying mouse in the pitch black might sound like an impossible task. In reality, some snakes have an incredibly advantageous signalling system in their heads: they are able to see heat. Warm-blooded rodents are a large portion of a snake’s diet, and with mice only giving off a small amount of body heat, this navigational skill is efficient and quick enough to allow precise and successful hunting at night. By the time the snake pounces, the mouse has minimal chance of spotting their impending death in the dim conditions.
The night sky presents patterns and points of light in the form of stars. In beautiful contrast to the black backdrop, it is no wonder that some species are drawn to their glow. Stars can help to guide animals in different ways: seals can recognise the unique patterns, some birds use a single bright star to find their way and dung beetles follow the path of the Milky Way’s spiral arm. Unlike seals, insects are too small to be able to notice each individual star, but the luminous band created by our galaxy’s arm is clear enough to provide direction and keep them moving in a straight line.
Soaring through the sky, it’s essential for animals like bats to know their position in relation to other objects. With limited vision, it would be easy to hurtle at high speed into a tree or another obstacle. This is where echolocation comes in. The majority of bat species use this strategy when they leave their roosts. Instead of viewing their surroundings, these animals listen to the objects around them by sending sound waves out from their mouth or nose. The pitch of this sound varies between species, with some producing sequences to cover all frequencies.
Generally, a low pitch is used for objects at a distance, while high frequencies present the bat with more detail of its surroundings. This includes the size and position of static objects, and the direction and speed of moving objects. When these waves hit something, the echo that is bounced back is picked up by the bat’s ears and analysed by its brain.
If you were stuck in a completely dark room, how would you walk to the door? Chances are you would put your hands out in front of you, feeling out your way to safety. Animals use the same method, but with a more technical and efficient system. Sensitive whiskers on the snouts of animals such as lemurs, badgers and dormice can aid foraging in the most complex habitats. Spending most nights in the dangerous heights of the trees, hazel dormice need these feelers so that they know where gaps lie between branches.
They move their whiskers in a movement called ‘whisking’. Brushing backwards and forwards in a cyclic motion, this is one of the fastest movements made by mammals. Special facial muscles found in whiskered animals allow these speedy movements so that the whiskers can constantly brush against surfaces as the animals travel. The uneven surfaces surrounding them are detected by hundreds of motion sensors in these modified hairs.
If you’ve ever opened your window at night to see a moth mindlessly following the light into your room, you may be fooled into thinking that these insects have developed rather limited navigational skills. The truth is that moths are extremely well-evolved to fly at night, using a sense called magnetoreception. Australia’s bogong moths were the first insects discovered to have a built-in compass, allowing them to follow the Earth’s magnetic field for migration.
Along with nocturnally migrating birds, these creatures are able to find specific locations in the country. It is believed that these insects have small magnetite crystals within their nervous system which are extremely sensitive to Earth’s magnetic field. This signal changes with the moth’s direction of flight, allowing them to check their position with Earth’s and keep them heading on the right flight path.
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