Mineral licks, whether natural or commercial, provide essential macro-minerals like sodium, calcium, and phosphorus, along with various trace minerals. These nutrients are often scarce in a deer’s normal diet during certain times of the year. Deer usage of these sources is highly seasonal, tied directly to the animal’s physiological demands. Activity at a mineral site peaks and then declines dramatically as the seasons progress and biological needs are met.
The Biological Drivers of Mineral Needs
Deer seek out mineral licks primarily to replenish reserves depleted by intense physiological processes. For bucks, rapid antler development demands a massive input of calcium and phosphorus. Antlers consist of significant amounts of these minerals, requiring bucks to draw heavily from skeletal stores and external sources during the growth phase. Does face a longer period of mineral demand due to reproduction, requiring high levels of calcium for late-term gestation and milk production during lactation. Both sexes also need to recover from the stress of the rut and the low-nutrient winter browse, making spring a crucial time for nutrient rebuilding.
Peak Use: Spring and Early Summer
The most intensive period of mineral lick use begins shortly after the spring green-up, typically in March or April. This timing coincides with peak demand for both sexes, as bucks begin active antler growth and does prepare for or have recently given birth. The lush, new forage is high in moisture and potassium, which can lead to a sodium deficiency. Deer must seek out sodium to maintain proper fluid balance and nerve function, counteracting the high water and potassium content of their spring diet. This craving for salt is the primary driver of the initial heavy use observed at mineral sites.
Seasonal Shift: When Mineral Lick Use Tapers Off
Mineral lick usage begins its noticeable decline in late summer, usually around August or September, as biological cycles complete. For bucks, the demand for calcium and phosphorus ceases abruptly once antlers fully harden and the velvet sheds. Once the bone structure is complete, the need for large quantities of growth minerals ends. Does also experience a reduction in mineral needs as fawns are typically weaned by late summer or early fall, eliminating the substantial demands of lactation.
Dietary Changes
The shift in the natural food supply also contributes to the taper-off in activity. As summer progresses, succulent forage dries out, and deer switch their diet to higher-calorie foods like woody browse and mast crops. These new food sources, such as acorns and nuts, often have different mineral profiles than spring greens, lessening the physiological drive for supplemental minerals. By late fall and early winter, freezing temperatures and snow cover make mineral licks less accessible and less appealing, pushing usage to its lowest point until spring.
Usage Differences Between Bucks and Does
While both sexes utilize mineral sites, their peak intensity and duration of use exhibit distinct differences. Bucks show an intense, sharp spike in use concentrated during the three to five months of active antler growth, concluding in late summer. Their visits are driven solely by the need to mineralize their rapidly growing bone structure. Does, conversely, demonstrate a longer, more sustained period of moderate usage that often extends further into the fall. This pattern reflects the extended needs of reproduction, spanning from late gestation through the entire lactation period until fawns are fully weaned.