Activity Cycles

The real secret to understanding the Moon's effect on Earth's inhabitants is the fact that all living organisms great and small exhibit alternating cycles of rest and activity. These, in turn, are directly related to the Sun or Moon, or both.

For example, humans have a circadian rhythm - we wake shortly after the sun rises, and we fall asleep after sundown. Nobody has to teach us this. Our bodies respond to changing light levels by producing the hormone melatonin that causes us to become drowsy and fall asleep. On the other hand, bats, owls and some species of snakes are nocturnal - they're on an after-dark activity schedule.

deer-moon.jpgAnd what about deer? The unique makeup of their light-gathering eyes and their weird four-part stomachs suggest they're neither circadian nor nocturnal. Some biologists classify whitetail deer as "crepuscular," or low-light creatures, but this is only partially true. Some nights herds of deer can be seen frolicking in fields, some nights they're nowhere to be found. Likewise sometimes deer are active during the day, and sometimes they're not. What gives? If you know where to look, you will notice a subtle rhythm to whitetail patterns involving the Moon. And this is what makes deer fairly predictable.

Deer And The Moon

It's important to note what happens when an organism gets out of its God-ordained rhythm: In a word, trouble. For instance, research from Harvard University involving 122,000 registered nurses dating back to 1976 revealed the perils of "shift work." Women who worked rotating shifts for six years or more experienced a 50 percent higher risk of heart disease.

Deer are no different. With its four-chambered stomach, a deer is designed to feed quickly to minimize exposure to predation, then retreat for security cover to "chew its cud." Deer must feed rhythmically or the microorganisms living in the first chamber of their stomach, the rumen, will die. Without these microbes deer won't last long, because they won't be able to digest woody fibers and food matter high in cellulose. So deer, like other species on the planet, feed on a regular schedule. Again, this schedule literally rotates around the Moon.

Each day, the Moon rises and travels across the sky above the horizon just like the sun, peaking at its midpoint before beginning to set. But unlike the sun the Moon rises a little later each day - about 51 minutes, on average. This makes tracking the Moon's comings and goings difficult and is largely responsible for keeping hunters in the dark over the years.

But that's been changing. Hunting-only lunar charts conveniently convert the Moon's overhead and underfoot positions into times of day. This is helpful information because the Moon's "overhead" position (and 12 1/2 hours later its "underfoot" position) coincide with predictable feeding times each day. Anglers have long used this lunar lore successfully, and now hunters are finding similar correlations.

How do we know this is fact and not folklore? Texas Tech University biologist Steve Demarais and whitetail management consultant Bob Zaiglin radio-collared 25 trophy bucks and monitored them from 1985 through 1987 in South Texas. The pair's extensive background enabled them to interpret and express their data in hunter-friendly terms, first published in the September 1991 issue of Buckmasters. Many insights were gleaned but one particularly stands out: Deer movements were most pronounced during the traditional hunting hours of dawn and dusk "when there was a 1/4 to 3/4 Moon." Further, the Moonless and Full Moon phases seemed to "break this pattern down."

The key variable here is Moon position: Quarter-Moons peak overhead (and underfoot) during low-light periods of sunset and sunrise. Coincidentally, bucks use the reduced light as cover and are more comfortable with their surroundings during early and late "Moon times" associated with these phases. This observation is substantiated with harvest data: Most deer registered at check stations throughout the nation are harvested during favorable morning and evening "Moon times." On the other hand, very few bucks are taken during Full Moons, largely because the Moon is directly underfoot during midday - a time when hunters are progammed into thinking they won't see many deer.


Cotulla Chamber of Commerce