By John Byrd
Published in UT Arboretum Society Journal (Vol21, No.1)
"Love the organisms for themselves first, then strain for general explanations, and, with good fortune, discoveries will follow. If they don't, the love and pleasure will have been enough." E. O. Wilson Naturalist
It was a beautiful May afternoon and *Leanne and *Tommy were conducting a routine survey of the 50 coverborards that are scattered along the power line that runs through the U.T. Arboretum. As they lifted board #14 Leanne spotted a shiny black serpent marked with yellow chains across the back (Fig. 1). Without hesitation she swept up the snake with one hand while simultaneously removing a cloacal thermometer from her pack with the other hand. Tommy carefully replaced the board and started filling in a data sheet with standard information (date, time, board #, air temp. etc.). Leanne called out a #1 for cloacal autohemorrhaging and then gently inserted the thermometer into the snake's cloaca (the chamber into which the digestive and urogenital ducts empty their contents) in order to record the internal body temperature.
This is a typical work day for Clinton High School and Oak Ridge High School students participating in research projects sponsored by the Clinch River Environmental Studies Organization (CRESO) and facilitated by the University of Tennessee Arboretum. The research is funded through a partnership that began in 1989 between the Department of Energy and the above school systems. The Department of Energy presently supports eight long-term projects. Five of them taking place exclusively at the Arboretum. This article provides a sampling of information that our investigations over the past ten years have revealed about black kingsnake (Lampropeltis getula nigra) populations studied at two different sites in Anderson County.
Captured kingsnakes often use behaviors associated with classical snake antipredator mechanisms, including tail vibration, tail thrashing, and cloacal discharge. When we grab kingnakes they frequently thrash their tail and smear feces and glandular products from the cloaca over the back of the restraining hand. Individuals that autohemorrhage protrude a bright red cloaca and supplement the cloacal contents with variable amounts of blood. Our study is the first to report cloacal autohemorrhaging for the black kingsnake and the literature reports only one other snake species (western long-nosed) that exhibits this behavior. We rate hemorrhaging behavior with a subjective scale from 1 to 3 with 1 representing a scant amount of blood released. In a manuscript that was recently accepted for publication by Herpetological Natural History we report a total of 53 hemorrhaging events involving 28 individuals (8 males and 20 females). Of the individuals identified as autohemorrhagers, 5 males and 11 females were captured two or more times. Only a single male had more than one hemorrhaging event, but there were 7 females, captured a total of 52 times, for which 31 hemorrhaging events were recorded.
Autohemorraging could represent a stress response or a range of possible antipredator mechanisms, from startle effect to attracting a predator to what may be the less critical tail area. Our experience suggests that the discharge could readily be smeared about the face of certain predators. The possibility that the bright red cloaca and blood may be novel to a predator (similar to dropping your pants and displaying a bright red rear end when being chased by a bully) relative to most members of the prey community has not escaped our attention. Developing hypotheses on why more than 70% of the hemorrhagers were females requires a closer look at the internal structure of the cloaca and scent glands (at least a portion of the blood came from the scent glands) of males and females.
You undoubtedly surmised from the above discussion that it is important for us to be able to identify recaptured individuals. We are not only interested in individual behaviors, but other data (e.g. temporal growth rates) are critical to understanding the life history strategies of our kingsnakes. Because snakes shed their skin several times during their active season, permanently marking them presents a problem. We solved this problem in the early phase of our study on the advice of a student researcher. She suggested that the schools $10,000.00 copy machine be used for something besides worksheets and tests. We now have over 180 belly patterns of individual kingsnakes (Fig. 2). The belly pattern identification method has held true year after year and the technique is also reliable for corn snakes and black rat snakes. These two species are more common than kingsnakes at the arboretum and are now part of a more inclusive long-term study. The ability to reliably identify recaptures has enabled us to amass growth rates for black kingsnakes (Fig. 3). Our study is the first to report growth data in nature for this species.
Due to consistent funding we have been able to use biotelemetry techniques to learn about a variety of kingsnake habits, including thermoregulatory behavior. Surgically implanted temperature-sensitive transmitters enables us to conduct around the clock monitoring of snake body temperatures and is far more informative than a sampling of cloacal temperatures from captured snakes. For example, in one 26-hour survey we were able to record body temperatures of two individual kingsnakes under extreme conditions (Fig. 4). You will notice in figure 4 that body temperatures varied only 3.5°C and 7°C during a period in which the ambient air temperature varied 20°C. Knowing where and why snakes position themselves in time and space under different environmental conditions is essential to understanding snake ecology. Mobility, optimum foraging, digestive efficiency, and reproductive success are all closely dependent on body temperature. A central question on which we are presently focused is how body temperature and thermoregulatory adjustments affect the distribution of the snake assemblage at the arboretum.
It will take years of methodical data gathering to shed light on many of our research questions. But student researchers are rewarded with increased observation and problem solving skills. There has been lots of talk in education about the need to help students become good problem solvers. The aspect that I personally find most appealing about the CRESO program is the opportunity to participate with students in the process of experimental design and overcoming some of the problems inherent in any type of field research. We are not above asking for help and we value everyone's input. So if you by chance see a high school student at the arboretum recording bird songs or lifting coverboards, please stop and chat with them about their summer "job".
*Leanne Jenkins started her snake research in the ninth grade. She has recently completed her biology and teaching degree at Middle Tennessee State University. She plans to teach in the local area and continue to work with CRESO. Leanne and Tommy recently had their kingsnake manuscript accepted for publication. See Abstract
*Tommy Thomasson is completing his first year of medical school at Vanderbilt University. He will be spending time this summer writing a paper on the extent of kingsnake home range overlap.