Birds are renowned for having an outstanding range of senses, all of which are of vital importance to their survival in the wild. Like people, birds have five senses that they depend on to thrive.
Birds rely on having excellent eyesight in order to fly, find food and evade predators. With the ability to accurately perceive motion and detail, their eyes are larger than human eyes in proportion to their head, so they can see tiny details two to three times better than we can.
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Although birds have a sense of taste, it isn’t as well refined as humans’ taste. Whereas we have 9,000 to 10,000 taste buds, birds have between 50 and 500, depending on the species. Birds can taste sweet, sour or bitter flavours and they know what the most nutritious sources of food are.
Sense of touch
Touch is an important sense for birds, particularly for flying. Changes in the wind speed and temperature are transferred down the feathers to nerves in the birds’ skin.
In addition, some birds possess special feathers called rictal bristles around their bill. Although ornithologists don’t fully understand their purpose yet, it is believed they may be useful when drumming on wood searching for prey or feeding on insects, by providing more sensitivity around the beak.
They may also be related to a sense of touch when birds take part in their important courtship ritual of mutual preening. Feathers themselves don’t have nerve endings – they work by transmitting touch to the skin.
Sense of smell
The sense of smell varies between species of birds and it is often the least-used sense, in particular for our garden birds. This debunks the myth that if we handle a chick to put it back in its nest, the parent birds will reject it due to the smell of human touch.
Some species have a better-developed sense of smell, which they use to locate food. These include vultures, albatrosses, kiwis, petrels, honeyguides and shearwaters. They can smell food from a great distance, particularly birds of prey.
Along with sight, a bird’s hearing is its most important sense. People often wonder how well birds can hear, since the ears are not visible in many species. In fact, the birds’ ears can be found below or behind their eyes and are covered with feathers known as auriculars to protect them. They are funnel-shaped to better focus the sounds.
With an average hearing range of between 1,000 and 4,000 Hz, birds have more acute sound recognition skills than humans – our range is between 20 and 20,000 Hz. Even though humans have a greater range, birds are extremely sensitive to tone, pitch and rhythm changes.
They use these skills to recognise other individual birds, even if they’re in a noisy flock. Birds are generally more sensitive to the tone of a sound than humans are, so they can recognise sounds more effectively, even in a noisy environment
The range differs among different bird species, with some having a wider range than others. For example, a horned lark can hear a range of 350 Hz to 7,600 Hz, a sparrow from 675 Hz to 11,500 Hz, a canary from 1,100 Hz to 10,000 Hz and a long-eared owl from 100 Hz to 18,000 Hz.
Birds use different calls, songs and sounds to mark different situations. Recognising the different noises is crucial to other birds. They must be able to ascertain whether the call is to warn them of a predator, make a territorial claim, or let them know where there is food.
Ornithologists study these different calls to identify birds and understand their behaviour. Without a good sense of hearing, birds would not be able to hear the mating calls of a potential mate, particularly in a large flock. Hearing is therefore vital to the survival of a species.
Unlike humans, whose hearing deteriorates due to age and exposure to loud noises that causes hair cells to die, birds’ hair cells regenerate continually, so they can maintain good hearing all of their lives.
Listening for prey
Ornithologists say most birds work out the source of a sound by tilting or moving their head, as humans do. Next time you see a blackbird or a robin walking along the ground, note the way it turns its head towards the soil.
Some experts say the birds can hear insects or worms just below the surface, although others argue they are looking for signs of prey or worm castings. Woodpeckers are said to be able to hear beetle larvae in the bark of a tree, hence they peck the tree to extract their prey.
The woodpeckers’ pecking at tree trunks has another purpose – the rhythmic drumming establishes their territory and attracts mates. They peck mainly to attract a mate in the spring.
The hearing of a nocturnal bird, such as the barn owl, is excellent. Even though they have perfect vision, the owl’s flat facial shape means the sound is funnelled towards their ears. An owl’s ears aren’t perfectly symmetrical. This helps them to locate where the sound is coming from.
People’s ears are symmetrical, therefore it can be difficult to ascertain from which direction a sound has originated, as the sound will hit both ears with the same volume and frequency. As the owl’s ears aren’t symmetrical, the sound will hit each ear with a different frequency and volume, enabling them to locate their prey more easily.
Some birds also use echolocation, in the same way that bats do. This means that they use the echo of their rapid chirps and clicks to work out where they are when in locations such as caves. Sometimes, even their superb vision may not be enough, and their hearing plays a part as well.
Although hearing is an important sense, for birds as well as humans, excessive noise can cause stress and anguish for people living near a building site, industrial premises, or noisy neighbours, for example.
As experienced acoustic consultants, Sound Planning provides a wide variety of products and services to help protect people from noise nuisance. We specialise in the design, supply and installation of noise control products. Please contact us to find out how our bespoke solutions can help you.