NATURE offers a feast for the senses, with the sight of vibrant colours and a symphony of sounds ranging from the howl of foxes to the delicate trill of birdsong.
Yet, among these sensory experiences, smell receives less attention. However, the natural world is rich with fascinating scents, each with its own purpose and significance.
Animal attraction
Many animals rely on scent to locate food, evade threats, and attract or assess potential mates.
Olfaction, the process of smelling, allows them to interpret and respond to their environment based on the odours they detect. From plants to animals, scent plays a vital role in survival and communication.
Over time, animals have evolved to recognise smells that signal opportunity or danger. A study in Northern Ireland provides an interesting example.
Researchers investigated why populations of invasive grey squirrels were declining after the reintroduction of one of their predators, the native pine marten, while native red squirrel numbers were rising.
The study revealed red squirrels, having coexisted with pine martens for generations, had learned to recognise this predator’s scent and take evasive action.
Grey squirrels, however, lacked this evolutionary adaptation and failed to respond to the pine marten’s odour, suggesting this is contributing to their decline.
This research highlights the importance of scent in the natural world, where survival often depends on the ability to interpret and act on olfactory cues.
Floral fragrance
It is tempting to think that the sweet fragrance of flowers exists purely for our enjoyment.
While the scent of honeysuckle on a late evening stroll in summer is undeniably delightful, the primary purpose of a flower’s fragrance is to ensure survival.
Like animals, flowers use scent as a means of communication.
They repel pests and predators while attracting pollinators. Herbal plants like rosemary, lavender, and mint produce aromatic essential oils from tiny glandular hairs on their leaves.
These bitter scents deter pests such as aphids, slugs, and even larger grazing animals like rabbits.
To attract the right pollinators, flowers have adapted their scent to be uniquely appealing to the insects they need to attract.
This is one of the reasons why choosing to plant native plants in our gardens is so important to support native insects, they have evolved alongside each other.
Timing the release of the smell is also important, flowers pollinated by bees and butterflies typically release their fragrances during the day, while flowers reliant on nocturnal pollinators, such as moths, emit their scents at night.
Signature scents
Foxes and badgers both use urine and faeces to mark their territory, leaving unmistakable signatures to define and defend their area.
In the West Cork countryside, the musky, characteristic ‘foxy’ scent is often a tell-tale sign of nearby fox activity.
Badgers take an organised approach, using communal toilets known as latrines which are small excavated pits where they deposit their dung. These deposits, smeared with scent from glands near their anus, signal group territory and warn unrelated badgers to stay away.
In these species, however, olfactory communication extends beyond toileting.
Both foxes and badgers have scent glands on their bodies, including a subcaudal gland near the tail.
In badgers, this gland is located just under the tail, while in foxes, it sits on the upper surface.
Recent research into the chemical composition of badger subcaudal gland secretions has revealed each individual has a unique scent.
Additionally, badger groups share chemical similarities, marking membership within the group.
This sophisticated scent system is important for defending territory and finding, evaluating and retaining breeding partners.
Badgers distribute this scent information by marking their environment and even each other.
Irresistible insects
I asked my sons, aged six and eight, about their favourite ‘nature smell’.
One replied ‘trees’, which was lovely, while the other, unexpectedly, chose shieldbugs; a perfect fit for this article.
Shieldbugs, small to medium-sized insects up to 2cms in length, have a distinctive shield-like shape.
They are also known as ‘stinkbugs’ due to a defence mechanism of releasing a strong-smelling liquid to deter predators such as birds and lizards.
These bugs seem to consider my son a predator, despite his harmless curiosity.
When handled, they emit a distinctive marzipan-like odour, a fragrant example of how insects use scent for self-defence.
Carrion beetles, such as the common sexton beetle, offer another example of the role of scent in the insect world.
These beetles, which feed on dead animals, have sensitive feathered antennae that can detect scent of carrion from up to 3kms away, guiding them with remarkable precision to their next meal.
My son gently investigating a hairy shieldbug, also known as the sloe bug, to see if he can detect their smell.
Brilliant beaks
I’ve written about the use of smell in mammals, flowers, and insects, but what about birds? Can birds even smell? For a long time, scientists believed most birds lacked a sense of smell. However, it is now understood that the majority of birds can smell and that many have a very well-developed sense of smell.
Birds have a special preen gland at the base of their tail.
When rubbed with their beak, it releases oil that they use to groom their feathers.
A key function of this oil is to waterproof and protect their feathers but it also produces an odour that helps birds recognise others of the same species and distinguish relatives from non-relatives, thereby preventing inbreeding.
Studies have shown male starlings seek out and incorporate fragrant herbs, such as yarrow, into their nests to attract females.
These herbs are thought to reduce bacteria and parasites, making the nests more appealing.
Fascinatingly, experiments suggest the starlings’ sense of smell becomes more acute during the breeding season.
Birds also use their sense of smell to find food.
Seabirds, such as sooty shearwaters and Northern fulmars, are drawn to the scent of fish, while native waders like the woodcock can detect the smell of worms beneath the soil, plunging their beaks with remarkable accuracy to retrieve them.
Breathe through your nose
The link between nature and human well-being is well established, with both visual and auditory contributions to this widely acknowledged.
Studies show spending time in nature boosts emotional health, reduces stress, and improves physical well-being.
Indeed there is now a growing interest in prescribing nature as a form of therapy.
Interested in how smells in our natural world might play a role in this, scientists at Washington University are exploring how natural chemicals in the great outdoors detected as ‘smells’ influence human health.
While we await their findings, it is clear taking time to enjoy nature, whether through sight, sound, or smell, has undeniable benefits.
So, get outside and smell the flowers, or even the shieldbugs!
