A salt lick, also known as a mineral lick, is a natural or artificial deposit of salts and other minerals that animals consume to supplement their regular diet. These deposits are commonly found in ecosystems where the general availability of these nutrients in forage is poor. The substances animals seek out are micronutrients that are often insufficient in the plants that make up the bulk of an herbivore’s diet.
The Essential Minerals and Their Physiological Role
Herbivores, in particular, frequently struggle to acquire enough sodium, as plants contain low amounts of this element. Sodium is a crucial electrolyte responsible for regulating fluid balance, preventing dehydration, and is necessary for nerve impulses and muscle contraction. Licks provide sodium chloride, but they are also rich in elements like calcium, magnesium, phosphorus, and trace elements such as zinc and iron. Calcium and phosphorus are important for strong bones and teeth, while magnesium plays a role in enzyme activation for energy metabolism. For many large mammals, these minerals are especially important during periods of high demand, such as lactation, pregnancy, and the rapid growth of antlers.
Primary Users: Ungulates and Large Herbivores
Hoofed mammals, or ungulates, represent the most frequent and visually prominent visitors to mineral licks. Species such as White-tailed Deer, Elk, Moose, Bighorn Sheep, and Mountain Goats have a well-documented dependency on these mineral sources. Domestic livestock, including cattle, horses, and sheep, also require and readily use artificial salt blocks provided by farmers. The consumption of minerals is often seasonal, peaking during the spring and early summer, coinciding with periods of intense physiological demand. Moose, for example, have a high requirement for sodium and will even seek out salt accumulated on roadsides from winter de-icing chemicals.
Diverse Users Beyond Hoofed Mammals
The need for mineral supplementation extends far beyond large, hooved animals, illustrating a widespread biological requirement across diverse animal life. Smaller mammals like porcupines, woodchucks, and fox squirrels are known to chew on mineral deposits or even objects with high salt content, such as shed antlers. Certain primates, including monkeys, will consume mineralized clay, a behavior known as geophagy, to obtain nutrients and potentially neutralize plant toxins. Birds also engage in similar behaviors; parrots and macaws in the Amazon visit specific clay licks. This behavior is thought to provide them with necessary minerals and also protect them from secondary compounds found in their diet.
Insects and Puddling
Many species of butterflies and moths engage in “puddling,” where they congregate on damp soil, mud, or even animal waste to sip fluid rich in sodium and amino acids. This sodium intake is especially important for male butterflies, who transfer these nutrients to the female during mating to improve egg viability.