Wednesday, May 22, 2013

How a Rattlesnake Eats: A Time Lapse


The snake begins the feeding process by locating the head of the prey to be ingested. This makes swallowing an animal with projecting limbs much easier since they can fold against the body and prevent impediment of the swallowing process. Notice how there is very little movement of the body advancing over the prey item; rather the prey item is carried into the gullet like a conveyer belt. The rodent is then moved down toward the stomach via rhythmic, lateral undulations.

The feeding motion that is seen in crocodilians and in some lizards is very animated; they toss and chomp at prey in order to arrange the meal for swallowing. Unlike snakes, crocodilians and lizards have larger heads to accommodate for prey size, limbs to aid in movement of body position and the prey, and the ability to rip, tear, and twist off flesh into manageable pieces if needed. Additionally, the heads of crocodilians and lizards are rigidly constructed, which means they lack the flexibility characteristic to snake skulls.

The relative immobility of the snake’s fore body during prey ingestion is made possible by the lose construction of the skull in concert with ligaments that allow for elasticity, this is called cranial kinesis or skull movement. A snake’s jaw does not come “unhinged,” despite the popular misconception for why snakes can ingest large prey with such small mouths.

The bottom jaw, or mandible, is not fused by bone at the front, as is the case in crocodilians and mammals; it is instead connected with flexible ligaments that allow the bottom jaw to spread outward and over a girthy prey item. The gape is also facilitated via elasticity. The bones of a snake’s jaw are themselves rather flexible, which is advantageous when force is being exerted on the mouth from all directions as large prey is engulfed. The upper and lower jaw in pit vipers is connected via a quadrate bone, this further aids in the vertical flexibility of the mouth over the body of large prey.

Thursday, April 25, 2013

Spring 2013


Spring is here. The budding of various species of deciduous trees is beautifully shaded in various hues of green; the Blue Ridge wilderness is awakening. The understory is for a seasonal moment bathed in sunshine, and the colorful wildflowers take this brief opportunity to spread their petals. Pollinators are everywhere, buzzing, flitting, flapping, and rapidly darting from nectar-baring plant to other nectar-baring plants of the same species. Thus the flowers breed. Mother bear is trailed by her cubs; they playfully tumble in the leaves making a mockery of mother’s foraging efforts. And in the warmest reaches of the Blue Ridge wilderness, ectothermic reptiles of various species are beginning their seasonal activities.

Early spring is when the timber rattlesnakes begin to stir; they greet the warmest days with just a glimpse of their coils, which are remarkably brilliant against a backdrop of fluffy leaves. With nighttime temperatures still hovering dangerously close to freezing, they will remain close to their refugia until a trend of reliable weather activates them to begin their seasonal migration. On the subject of hibernating timber rattlesnakes, it seems reasonable to assume that a species known for their impressive assemblages would be erupting from underground en-masse on a warm spring day; however, this does not seem to be the case at southern latitudes.

An interesting study published in August 2010 by Jeffery Mohr, revealed that highland South Carolina timber rattlesnakes overwinter singly and occasionally in pairs, much like their piedmont/coastal ecotypes the canebrake. Based on my observations, it could be forgiven to assume the same could be said of Georgia’s highland timber rattlesnake, being on roughly the same latitude as the South Carolina population. Telemetry studies of the seasonal temporal and spatial activities of Georgia mountain horridus can confirm or deny the aforementioned assumption. Northern Populations of Timber Rattlesnakes appear to be strongly communal, social animals that tend to aggregate/live in centralized “colonies”. The occupation of historical colonies is primarily dictated by environmental constraints and has lead to shared hibernacula, gestation and basking sites. Colonies are primarily found on open, rocky, south facing slopes, at higher elevations.

The difference in aggregation as fostered by the environment is not necessarily a disadvantage to their sociality as much as it is a testament to the forces of natural selection at work in shaping society at high latitudes. As Mohr suggests in his paper, timber rattlesnakes in the north are faced with longer, colder winters, coupled with fewer choices of available overwintering sites that can protect them from prolonged spells of freezing temperatures. Conversely, southern populations frequently see mild winters with very few lengthy stretches of freezing temperatures, so it is likely that there are a variety of microhabitats in the environment that can adequately serve as hibernacula. Thus, the southern climate relative to the environment did not select for communal denning.

Monday, February 25, 2013

Timber Rattlesnakes: Fixed Videography 5-22-12


In the spring months, the mornings start off cool and windy, and the rocky grey landscape is lonely and silent with the exception of windblown vegetation rustling. Some mornings are even still cool enough that spirals of steam can be seen pouring from the mouth and nose as one exhales, especially during a labored climb to a mountain top study site. The dullness of the winter landscape is slowly transitioning into the vibrant verder glow that is the beauty of an Appalachian forest in full leaf. This is my favorite time of year.

While all the serpents are laying in sluggish rest beneath stones, I make my way on site under the still visible moon and set up my camera to capture their awakening with the morning sun. After setting up my camera, I take a seat many yards away – but close enough so I can manipulate the camera with a remote, and I wait. The climb caused blood to rush and warm my body; however, my metabolic warmth escapes into the ground bellow me and into the air around me, so I shrug on a long sleeve. This is always a good time for writing, it is in these moments when I am alone at some of the loftiest altitudes Georgia has to offer that I find the peace and quite to put a creative pen to paper.

Before I know it, the sun peeks high enough over the mountainous horizon that its photons wash across the landscape like an electromagnetic rain, much to the delight of my ectothermic friends. Once I see their scaly bodies ooze from beneath the stones, I click on the camera and run it until the batteries are dead. Here is a glimpse into a few of those moments. This video is sped up 400% in I-Movie; there are spaces of tens of minutes where the snakes simply do not move at all. The volume is down, and in some cases off because of the wind.

Tuesday, February 19, 2013

Fixed Videography From Spring 2012


These timber rattlesnakes are dull, have a patina of dirt from being underground all winter, and one, as you will see, is deep in the blue of ecdysis, all signs of freshly emerged spring rattlesnakes.

Something that has always impressed me is how quickly the snakes re-surface from underground after I have set out the camera equipment. None of the fixed video I have taken is much more than a half hour to fifty minutes in length. This means the snakes are re-emerging after just a few minutes of my leaving the scene.

The response at the end is typical of when I return to gather my equipment. Whenever possible, they pull their coils inward in such a way that allows them to retreat with the head poised close to the more vulnerable tail. This allows for easy defense against anything that might try to grab the snake by the tail. I simply use a snake hook to gather my camera, and then leave to allow the snake to settle back down.

This video is only a brief glimpse into the complex life that a timber rattlesnake leads, but in these tiny moments a great deal about how they interact with their biotic and abiotic surroundings can be inferred. With these technologies, we are learning things that were once obscured to and even dismissed by the herpetological pioneers Klauber and Kauffeld.

Mixed Effects Models and Extensions in Ecology with R (2009 Edition) b

Monday, February 18, 2013

Spring 2012: A Brief Encounter With a Black Bear


Studies in Zoology: A Book Devoted to Animals and Animal Life at the C

I was seated on cold stone, obscured by dwarfed pine, bunch grasses, and a fragrant tangle of herbs. The morning air was just cold enough that sitting still was uncomfortable. All around the woods were beginning to awaken. Squirrels scratched along their canopy highways, sweet birdsongs were coming into tune, and a clear blue sky above suggested a fine day was ahead.

My focus was on a spot among the rocks where I knew several gravid female Horridus to be resident, and I was waiting patiently for any of them to emerge, pull themselves into a tight coil, and wait on the radiation to elevate the temperature of their gestating bodies. It is amazing how slowly they drag their length out from within their burrows. I have filmed morning egress before, and each video is about twenty to thirty minutes in length, during which the snakes are actively moving only about a fraction of the total time. The action in the films is so slow that I speed them up so as not to get board watching it. Seeing it in real life, in the beauty of the out doors, is much more thrilling.

I was busily writing environmental and climate descriptions into my notebook, when a curious sound caught my attention. On this occasion, I was particularly alerted to certain sounds since this was the morning after the night the sound of many coyotes erupted near camp and caused me to lose some sleep. I started to stand in order to see where the sound was coming from and what was causing it. Twigs snapped in succession, obviously something was walking through the adjacent wood line toward my location.

I finally picked up on a black shape moving from just within a green curtain, pierced here and there by coarse woody debris. My pulse quickened as my initial assessment of the creature was that it might be a big black feral hog, and they usually are not alone. I stood, began to gather my gear so I could leave quietly, and then I realized that it was just a black bear.

My pulse was still elevated, and naturally, I quaked a bit in the animal’s presence. I would have been more worried about a heard of pigs joining me at my seat on the mountain than I was by a bear, as a matter of fact, I welcomed the sight of this bear and the chance to film it. It continued its march until it was in full view out in front of me, and by now I was covertly video recording.

What I initially thought was that the bear would just cross the rock face in front of me, and simply re enter the woods on a bee line path; however, it turned toward me, still unaware of my presence. After only filming it for a few short seconds, I had to break my silence to inform the bear that he was not alone. I called aloud: “here bear,” which is apparently the go to vocabulary for shooing off a bear as I have gathered from locals. It looked up directly at me and I looked directly back, not budging from my spot. I figured it hadn’t quite seen me because it kept coming, swaying its head around, looking.

Not wanting to surprise the bear, I moved out of my cover and stood up as tall as possible, and repeated my taunt: “here bear”. Those that know me know that I do not stand very tall, but I was able to coerce the bear to take a different path. Just to be sure that the bear was not going to return, at least for the moment to allow me to leave, I took a few steps forward, always using my voice to encourage the bear to move along.

As much as I love seeing wild bears, I was not in love with the idea that I was hidden away for one to flush from the snags like a hunted rabbit. After hearing the bear crash off into the depths of the valley, I took my leave of this particular site and went to another location for the day.

Zoo Med Laboratories - Adjustable Snake Hook 7.25 - 26 Inch - TA-25

Wednesday, February 6, 2013

Coyotes Laughing in the Night


June 2012. The light faded, and the smooth transition of diurnal voices to nocturnal conversations reverberated. The cool breeze carried the fresh scent of mint tea on soft currents. The evening hour was quite a pleasure after a lengthy day of counting rattlesnakes in sun, it provided a much needed respite and the opportunity to crack open my thinking book to record thoughts that were otherwise fleeting while I was busy.

I chose to camp in a location just yards away from one of my sampling sites, but it was also in an area frequently trafficked by feral hog and other game. I worried less about bear than I did the hogs; the hogs are problematic, dangerous and bold. So I decided to place my tent-cot in the bed of my truck in order to sleep elevated up off of the ground and away from any trampling hooves. In the last moments of sunlight, I could already hear hogs feeding from within the neck-high grass of an adjacent game clearing. The sweet smell of my tea was likely not helping my desire to avoid a hog invasion of my camp, but it sure was a refreshing brew beneath the slowly appearing stars.

I had scarcely placed my head upon my pillow, when suddenly out of the black of night; coyotes began to laugh from within the forest nearby. It began as quite a domestic sound, but as their conversation continued, their howls intensified to a more sinister tone. They cackled and cried as the pack ran swiftly through the woods along which I was camped. I was unsure if they were tormenting a meal beneath the hunter's moon, or if they were simply engaged in playful canine antics. The sound was thrilling and also slightly chilling.

Predatory noises erupting suddenly in the night was undoubtedly frightening to our Paleolithic ancestors living in the wild Pleistocene, and it likely caused them to keep close to their firelight for security. The desire for light when shrouded in the dark unknown is an emotion that still tugs at the psyche of modern humans as a reflex of our past. I reached outside of my tent and ignited my lamp, and it cast a warm, comforting glow in a perimeter around my camp. I slept soundly with my lamp standing sentry over me, a beacon in the night to stave off the American Jackal.

Rite in the Rain Outdoor Journal

Friday, February 1, 2013

In Reverence of Rattlesnakes


Surveying rattlesnakes on a den is an entirely different affair than searching for them in the tin fields of the low country; something I learned gradually over time and with each new visit to an assemblage. Quite often I find myself in remote places and on dangerously uneven terrain. I suit up like a medieval knight in full harness, ready for the hastiludium. Leather boots or stout hiking shoes cover my feet, half chaps protect my legs bellow my knees and I always have on a good pair of Carhartt pants or jeans to deter snags and flesh ripping thorns. Poison ivy is abundant in timber rattlesnake habitat and often I spend the whole summer with mild blisters, but as a precaution I almost always wear a shirt with sleeves I can roll down.

Once a denning area is reached, it’s frequently necessary to bushwhack through dense foliage, thorns, and other greenery (especially summer time) in order to explore the many smaller facades and bordering escarpments. Sometimes I have to take to my belly, not unlike the creatures I seek, and slither under low hanging pitch pine branches or through a choking mass of laurel. On many occasions, I find myself battling through the skeletal remains of fallen trees; their dried, lifeless forms make for a frustrating obstacle course as well as a good place to hide snapping jaws. I can only imagine what I must sound like to the quiet and concealed animals living on the adjacent ridges. My shuffling feet through ankle deep leaf litter, a snap and crack that echoes like gunshots as I smash through deadfall, and the occasional vociferous expletive when the trees fight back.
Firefly Encyclopedia of Reptiles and Amphibians By Mattison, Chris