Natural History of the Racer Coluber constrictor

by Henry S. Fitch

A racer suddenly startled by close approach of a human usually flees at high speed. The first part of its course, up to 20 feet or more, is marked by a violent lateral thrashing of the body and tail, which may help the snake to gain speed, but which seem chiefly designed to draw attention of a potential attacker to the spot that the snake is leaving. In any event, the mode of progression abruptly changes to a swifter and much smoother travel, and the snake may seem to vanish completely or as it glides rapidly away, its course may be marked by the slowly waving tops of tall grass. The trend of travel away from the site of disturbance is in an irregularly zig-zag course. The method of crawling, with lateral undulations of the body, supported against scattered pivot-points along the way, tends to prevent the snake from moving more than a short distance in a straight line.

In checking traps along hilltop rock ledges in October, I have often flushed racers that had come to the ledges searching for hibernation dens. In such an instance the startled racer would usually dart away down the steep slope at unusually high speed, and within a few seconds might have covered 100 feet or more, progressing with a minimum of lateral undulations, and seeming to flow or coast over the ground surface with scarcely any effort. Although coursing downhill in this manner provided an effective method of escape, racers startled at the ledges or on other sloping ground sometimes followed a course parallel to the ledge, or even turned uphill, with disastrous slowing. Often I have accomplished capture by hand, by the strategy of running downhill to get below the escaping snake, causing it to turn back up the slope, there to be slowed to the extent that it could be overtaken.

A racer that has been flushed, and has disappeared after creating a commotion by its violent thrashing, may, within a period of minutes, return surreptitiously to the vicinity, gliding back slowly and silently from the direction opposite that in which it departed. It may climb into a tree or bush where, lying stretched on outer twigs and concealed in dense foliage, it will sometimes permit close approach, rather than reveal its presence by moving. If too much disturbed however, such a snake will move away, higher, or to the opposite side of the clump, with a slow and stealthy gliding motion which is likely to escape detection. The sudden stops and abrupt changes in direction make it difficult to follow the course of a climbing racer, even though it is moving slowly. The tendency to climb to escape danger seems to be especially strong in the western subspecies, C. c. mormon. In my years of experience with the racers in the chaparral belt of western Oregon and California, I found that one of the most characteristic responses to danger was to climb into a bush or low tree and seek concealment in the thick foliage. In most instances the snake was from one to eight feet above the ground; usually it did not attempt to climb high in a tree even when there was opportunity to do so. The racer's prowess as a climber is limited. In thick brush where its weight is supported by numerous stiff twigs simultaneously, it is at home and can travel rapidly, but it cannot cling effectively to rough bark of a vertical tree trunk as can the rat snakes (Elaphe sp.) and others that are more specialized in their arboreal adaptations. Chaparral-type shrubs such as Ceanothus cuneatus and Arctostaphylos viscida were those in which western yellow-bellied racers were seen climbing most frequently. Crab-apple (Pyrus ioensis) and haw (Crataegus sp.) were the shrubs most frequently utilized by blue racers on the Reservation. Carr (1950:80) noted that Florida racers were much less given to tree-climbing than were those of more northern regions. C. c. stejnegerianus of southern Texas is reputed to have arboreal tendencies highly developed (Mulaik and Mulaik, 1942:14).

The racers kept in an outdoor enclosure in the summer of 1962 spent much of their time above the ground, climbing in several walnut saplings. Usually in the warmer part of the day three or four of the five racers in the pen were climbing. In the trees a racer usually lay extended or in a loose coil among foliage in the outer twigs, at a height of five to 12 feet. Such a snake might rest for hours in almost the same position. Racers do not ordinarily enter the water voluntarily, but they are swift and efficient swimmers when the need arises. On one occasion a large female, seen near the edge of the pond on the Reservation, and approached from the landward side, took to the water without hesitation and swam strongly to the opposite shore more than 100 feet away. Other observers have recorded similar incidents.

A racer that is suddenly startled at close range may make no attempt to escape, but instead may coil and perform slow writhing movements, with the head pressed to the ground and concealed beneath part of the body. Musk, exuding from the anus is spread over the body surface as the movements continue. Only a small percentage of the racers found free in their natural habitats reacted in the manner described. In each such instance, the circumstances were such that the racer was prevented from making its usual rapid getaway, either because temperature was unusually low for activity, or because the snake was away from suitable cover. After removal from a live-trap, with handling, and especially clipping of scales, racers were much more likely to behave in this passively defensive manner, which seemingly constitutes a second line of defense in snakes which have been prevented from escaping—either cornered, captured, or injured by a predator. The musk is creamlike in color and consistency, and is secreted from sausage-shaped glands in the base of the tail. Its odor is rather disagreeable, but less so than that of musks of various other genera. Also, it is less penetrating and lasting than many other musks. In handling the racers removed from traps I attempted to avoid being smeared with the musk by grasping the snake by the tail and neck and keeping its body stretched out. While the snake was being examined, and measured a droplet of musk would form at the anal orifice and would begin to flow down the snake's body. To avoid contact with the musk I would wipe away the droplet with a paper towel or leaf, but the musk droplet might be replaced several times within the few minutes that the snake was restrained.

A racer that is confronted with an object arousing its suspicion or indicating possible danger, may move away slowly with a characteristic "threat display." The forebody and neck are held rigid, well off the ground, and slightly arched, with the neck flattened in a vertical plane—causing this part of the snake to appear from lateral view larger than it actually is. The tongue is protruded frequently and waved slowly. A racer that has been disturbed and is trying to gain shelter in a direction that brings it closer to the danger usually will adopt this tense attitude, but a single threatening movement will cause it to abandon its circumspect pose, and panic in an attempt to reach the nearest shelter in the shortest possible time.

A common response to an alarm is to vibrate the tail. The tail being long and slender is vibrated much less rapidly than the short, muscular organ of a rattlesnake, or even the medium-short tail of a bull snake. The rapid twitching produces a characteristic sound in dry vegetation. A racer that vibrates its tail is fully active and aroused; the sound is heard as the snake pauses before it makes a dash for shelter. At times the sound probably functions as a decoy to distract the attention of potential predators, affording the racer an opportunity to escape.

A racer that is cornered or captured usually puts up a spirited struggle, striking vigorously and repeatedly at its tormentor. If only cornered, it will make slashing strokes at the enemy, jerking back to a coil from each stroke in a manner that causes the teeth to lacerate the enemy's skin in long scratches if the stroke finds its target. The rapid recoil often causes teeth to be jerked from their sockets and left embedded in the wound inflicted by the bite. On many occasions in sustaining a bite from a racer I have received such teeth which have remained undetected for a day or more until soreness and festering led to their discovery and removal. A racer that is grasped may deliver several bites within a few seconds, chewing vigorously to imbed its teeth to the maximum at each bite.

If grasped by the tail and held clear of the ground, the racer would swing its body with a rapid whirling and twisting motion, which in a few seconds would twist off the end of the tail, unless countermeasures were promptly taken. Many racers, especially the larger and older ones, have parts of the tail missing, as a result of such escapes, and perhaps also from freezing in hibernation or from certain injuries and infections. If grasped by the body, the racer struggles with a violent lateral thrashing to break the grip of its captor, at the same time striking to bite and discharging musk, urinary wastes and feces.

Many of the racers examined bore scars from wounds that were probably inflicted by predators. A few had survived severe skeletal injuries, involving deformation of the spinal column or extensive tearing of muscle and connective tissue layers of the body wall, altering the normal body shape. A more frequent type of injury involved chiefly the integument, which had been ripped open by the teeth, claws, or bills of adversaries, despite the fact that the skin is remarkably tough and leathery. Patches of scar tissue with scales in irregular sizes, shapes and patterns characterized such injuries. The most frequently observed type of injury involved loss of part of the tail. Usually only a small terminal part was missing, but occasional stub-tailed individuals had lost as much as three-fourths of the tail.