The heat of summer makes its final stand in the month of August. Since July 2, the average high temperature for the Washington D.C. area has been 88 or 89°F. Only by August 14 does the average drop to 87°F. In the bounty of this solar heat, or energy, the various life forms of our forests are doing everything they can to use and conserve this energy to complete their seasonal cycles and prepare for the winter days of depletion.
The plant community as a whole acts like a living manufactory, pumping the atmosphere through it’s leaves, converting the energy of the sun through photosynthesis to create the foods that will enable the plants to eat, survive, and reproduce. Within its stems and roots, these starches will be stored and utilized over the winter as a fuel to maintain the plant’s minimal metabolic needs, serving much the same function as brown fat does for mammals.
Not only must the plant community produce enough food to service its needs, it must produce the food to fuel the metabolism of virtually all of the life forms of our forests. Viewed another way, the quantity of green plant matter produced determines the quantity of other life forms that can be sustained.
The heat of July and August has maximized the metabolism of the insect world, supporting the maturation of another season’s crop of mating insects. I associate August with the sounds of the annual cicadas, katydids, field crickets, grasshoppers and others. These August evenings can be downright raucous from the back porch. It is clear that to these life forms, this is their month of glory.
A number of fungi are producing spore-bearing fruits, also known as mushrooms, at this time of year. Many fungi are attached to plant roots, absorbing nutrients from the soil and feeding them to the plants. In return, the plants provide some stored starches to these fungi. In fact, 90% of all plants contain these mycorrhizal fungi, which include the boletes, amanitas, morels, puffballs and truffles.
August has another association with me. The peak of rattlesnake activity is late July and August. Out of their wintering hibernacula since about May 1, the males have been busy foraging within about a mile or two of their dens. The nature of their foraging is in the form of laying in a coiled position, waiting to ambush any small mammal that happens to wander too close to the unscented predator, who has the advantage of the heat-sensing pits.
But now, the males are actively moving throughout their territory, seeking out non-pregnant (non-gravid) females. Females will reach maturity at age 6 or 7, with a lifespan of ten to fifteen years average. Mating will peak in early August. Once mated, the females will hold on to the sperm over the winter, not permitting fertilization until June. With a gestation period of about 2 ˝ months, birthing will begin in late August. This brings into question an interesting enigma. Scientific dogma states that rattlesnakes mate in the spring, giving birth in August of that same year. The source of this apparently dates back to a paper written in 1907 by R. L. Ditmars. A very logical presumption, based on gestation period, and the communal nature of rattlesnakes on emergence from their wintering dens, but one not supported by observations. Since that time, many authors have repeated this assertion without adding any supporting documentation. However, documentation supports the 13-month period between mating and birthing. But why would this be the case? Why doesn’t the female permit immediate fertilization and give birth the same season? The answer to this question eludes herpetologists at the present time.
Females give birth on a three-year cycle. Thus in any given season, only a third of the females give birth. Pregnant female rattlesnakes usually used certain favorably exposed rocks for birthing. These sunny rock slabs are usually only 50 to 200 yards from the wintering den sites. As many as 17 females have been found in PA at these favored birthing ‘rookeries’.
About two weeks after the birthing of the 8 to 10 neonates, the female will travel to the hibernaculum with the young soon following the scent to the den, where a population will average 30 to 60 snakes, with larger dens supporting 120 to 200. Copperheads and occasional black rat snakes will also overwinter with the rattlesnakes. In fact, if the young lose the scent of the mother on the way to the den, they have been known to follow the way of a black rate snake going to the same destination. This is how the black rat snake earned one of it’s common names; the pilot snake.