Salt is essential to life on Earth.
It doesn’t just make our food taste great, it actually keeps our bodies, as well as the bodies of nearly every animal, functioning properly.
Salt, or NaCl, is the main source of sodium and chloride ions in the diet of most animals – from mammals and birds to invertebrates and insects.
Animals don’t just like salt, they need salt in their diet to maintain their own health. The sodium ions are essential for nerve and muscle function, regulation of body fluids and controlling blood pressure (for those animals that have blood). Some animals need artificial salt blocks, others congregate around naturally occurring salt licks.
Salt licks can be found across the globe, and are a relatively common occurrence. In springtime, when animal development is at its highest, wild animals lick these mineral deposits to contribute to the healthy growth of bone and muscle.
Salt licks are important in ecosystems that are devoid of nutrients.
What (Exactly) Is Salt?
Yes, it is probably the one found next to the pepper shaker.
Yes, it is used quite excessively in Lays Classic Chips.
But have you ever stopped and wondered what really is salt? Where does it come from?
Well, salt is a naturally produced mineral and, quite simply, it is found everywhere. It can be found in the ocean and on the land. From the Dead Sea to termite mounds of Africa.
Salt is also referred to as sodium chloride, or NaCl, a name derived from the abundance of sodium and chloride ions. It is incredibly important in the diets of most animals we share our planet with.
Wild animals seek out mineral, or salt, licks. Species, such as elephants, travel vast distances to seek out salt licks.
But why do animals go through all this trouble?
The Importance Of Salt
Most animals need salt in their diet to maintain a well-functioning body.
A healthy amount of sodium chloride in the body is important to carry out electrical nerve impulses, constriction and relaxation of muscles and balances fluid levels within the body.
Of course, all we humans need to do is to pop down to the local grocery store and buy a ready-filled salt shaker. Or, if you lead a particularly active lifestyle, chug a glass of salt-rich electrolytes.
Animals, on the other hand, do not have this luxury.
So, how do they get salt into their diet? For this, we’ll have to break it down into domesticated animals and wild animals.
For domesticated animals, things are easy.
These are animals that are kept as agricultural livestock (such as cows and sheep), companion animals (such as dogs and cats) or working animals (such as camels and horses).
Whilst dogs and cats obtain most of their salt from their diets (animal protein has naturally occurring salt stored in muscle tissue), herbivorous animals, such as cows and horses, need additional salt in their diets.
Historically, farmers have provided artificial salt licks for their animals to encourage healthy growth and development. Without salt in an animals diet, body cells will expand with excess water, causing a condition known as hyponatremia. This can lead to severe health problems, such as uncontrolled vomiting and diarrhea.
Oftentimes, a salt lick is in the form of a block and hung by rope or mounted on a platform, accessible for animals to lick to their heart’s content.
Not only does this act as a form of enrichment, it also encourages hygienic behaviour, as it minimises the contact with the salt lick to the faeces-covered ground.
But what about wild animals? Humans can’t go around hanging artificial sat licks in all corners of the globe. So, what then?
Fortunately, there are naturally occurring places where salt can be found in abundance. Perhaps the most common are mineral, or salt, licks.
Salt licks are natural mineral deposits whereby animals in nutrient-deficient regions can supplement their diet with added nutrients. Many species of ungulates, such as moose, aggregate around salt licks year round. However, during the spring and summer months, when bone, antler and muscle growth peaks, salt licks are frequented more often.
Competition is fierce around salt licks, and some species ungulate will travel over 15 kilometres. However, elephants have been known to walk hundreds of miles in their search for food, water and salt.
Across the globe, there are three main types of salt licks that wild animals like to visit. These are either wet and boggy areas (often found in seepage sites), dry earth (often clay deposits) and rock faces. In each of these sites, animals either eat the soil – a process referred to a geophagy – or lick the sodium-rich walls.
However, other sources of naturally occurring salt deposits include termite mounds, plant roots, borehole water, soil and wood ash.
What Animals Use Natural Salt Licks?
Many carnivorous animals absorb salt through their diet, such as eating meat or shellfish. Blood is particularly high in salt.
However, herbivorous animals, or animals that only eat plant matter, cannot obtain a healthy amount of salt in their diet of just plants, leaves, grass or fruit.
To compensate, a wide range of animals, from various taxa, can be found congregating around natural salt licks.
Like watering holes, salt licks are a biodiverse hive of activity of both herbivores, looking for salt and minerals, and carnivores, looking to prey on distracted herbivores.
Species that can be found around, and like, natural salt licks include:
- Bovine species (bison, yak, gaur)
- Some species of birds
In Peru, and other South American countries, bird species, such as macaws, parrots and parakeets, can often be found on clay banks.
But why would a typical aerial species be found clinging onto perilous clay banks?
One hypothesis, pr0posed by Donald Brightsmith, suggested that the Amazonian clay is rich with vital minerals that cannot be found in the bird’s natural, plant-based diet. Another study suggests that geophagy – the intentional consumption of clay or soil – is concentrated in tropical rainforests, where sodium in the loose topsoil is quickly washed away. Only sodium stored in the hard clay is accessible to species.
Like mammals, sodium plays an important role for nerve function and muscle contraction in birds.
The study goes on to suggest that birds that frequent the Amazonian clay licks had an estimated 40 times more sodium than birds that did not visit salt licks. As a result, egg clutches had a higher hatch success rate.
Elephants are another species that supplement their diet with salt and other trace minerals.
Many populations of elephants use their ever-growing tusks to churn up the soil on foraging routes and eat clumps of dried soil to obtain the precious salt. Some populations lick rocks with a high sodium content.
However, one population of African elephants takes things one step further. They physically mine the mountainside.
Found in the Mount Elgon National Park, on the Kenyan-Ugandan border, one population of salt-loving elephants have been found to quarry the low-lying, volcanic slopes.
Much like their mud-chopping relatives, this population of elephants use their tusks to break off pieces of cave wall, which they chew and, eventually, swallow. A study suggests that, over a period of one hour, up to 20kg of salty soil was ingested by a particular bull elephant.
Many species of ungulates, or hoofed animals, have an exceptional sense of smell, and are capable of sniffing out salt licks. Deer, for example, are thought to have over 250,ooo,000 scent receptors. This makes their sense of smell 1,000 times stronger than our own.
Other species of ungulates, such as tapirs, like salt licks not just for their physiological gains, but also for social interactions.
Tapirs are often solitary mammals. However, in a study by Yuko Tawa, it was observed that both female and male tapirs were present as the same salt licks at the same time. This suggests that home ranges overlap and the tapirs gain sensory information about other tapirs in the region.
Salt is so much more than just a food flavouring for us humans.
When are we going to realise that the world doesn’t revolve around us?
Salt is an incredibly vital mineral needed by virtually all life on earth.
Although domesticated animals often get given a helping hand, in the form of artificial salt blocks, wild animals have to rely on their own ingenuity and, most importantly, their sense of smell.
Many species of herbivorous animals seek out naturally-occurring salt licks, in the form of rock faces, wet bogs and clay to obtain additional nutrients in their body. Salt is vital to maintain physiological processes in the body, such as fluid balance and muscle contraction.