Many animals regularly visit mineral licks to consume clay, supplementing their diet with nutrients and minerals. In tropical bats, lick visitation is associated with a diet based on wild figs (Ficus), which have very low levels of sodium,[3][4] and licks are mostly used by females that are pregnant or lactating.[5]
Some animals require the minerals at these sites not for nutrition, but to ward off the effects of secondary compounds that are included in the arsenal of plant defences against herbivory.[6] The minerals of these sites usually contain calcium, magnesium, sulfur, phosphorus, potassium, and sodium.[7][8][9][10] Mineral lick sites play a critical role in the ecology and diversity of organisms that visit these sites, but little is still understood about the dietary benefits.
The paths animals made to natural mineral licks and watering holes became the hunting paths predators and early humans used for hunting. It is hypothesized that these salt and water paths became trails and later roads for early humans.[11]
Nonetheless, many studies have identified other uses and nutritional benefits from other micronutrients that exist at these sites, including selenium, cobalt and/or molybdenum.[12][13] In addition to the utilization of mineral licks, many animals suffer from traffic collisions as they gather to lick salts accumulated on road surfaces. Animals also consume soil (geophagy) to obtain minerals, such as moose from Canada mining for minerals from the root wads of fallen trees.[14][15]
Artificial salt licks
Artificial salt licks are used in the husbandry of livestock and to attract or maintain wildlife, whether it be for viewing, photography, farming, or hunting purposes.[16] Maintaining artificial salt licks as a form of baiting is illegal in some states in the United States, but legal in others.[10]: 413 Inadvertent salt licks may lead to unintended wildlife-human interactions.[17]
Svärdsjö sheep, an endangered Swedish local breed, licking salt
In Norse mythology, before the creation of the world, the divine cow Auðumbla licked salty ice for three days and uncovered Búri, ancestor of the gods and grandfather of Odin. On the first day as Auðumbla licked, Buri's hair appeared from the ice, on the second day his head, and the third his body.[19]
^Bravo, Adriana; Harms, Kyle E.; Emmons, Louise H. (2010). "Puddles created by geophagous mammals are potential mineral sources for frugivorous bats (Stenodermatinae) in the Peruvian Amazon". Journal of Tropical Ecology. 26 (2): 173–184. doi:10.1017/s0266467409990472.
^Emmons, L. H.; Stark, N. M. (1979). "Elemental composition of a natural mineral lick in Amazonia". Biotropica. 11 (4): 311–313. doi:10.2307/2387925. JSTOR2387925.
^ abAtwood, T. C.; Weeks, H. P. (2003). "Sex-specific patterns of mineral lick preference in white-tailed deer". Northeastern Naturalist. 10 (4): 409–414. doi:10.2307/3858657. JSTOR3858657.
^Mills, A.; Milewski, A. (2007). "Geophagy and nutrient supplementation in the Ngorongoro Conservation Area, Tanzania, with particular reference to selenium, cobalt and molybdenum". Journal of Zoology. 271 (1): 110–118. doi:10.1111/j.1469-7998.2006.00241.x.
