Turtle Ecology and Feature Taphonomy in the Chesapeake Region

April M. Beisaw, RPA

Presented Before the 2001 Meeting of the Society for American Archaeology, New Orleans, LA

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Introduction

In the Chesapeake Region, small numbers of turtle remains are commonly encountered during feature excavations. Generally quantified but rarely interpreted, turtle remains are often discounted as a commensal species, a species native to the area which may or may not represent a food source to humans. Commensals commonly include rodents, reptiles, and amphibians, many of which are edible but few of which are a standard part of the human diet. Musk rats and Mud Tutles, are affectionately referred to as the "savage tidbits" consumed by hunters (148) by Henry David Thoraeu in Wladen. Thoraeu himself admits "Yes, for my part, I was never unusually squeamish; I could sometimes eat a fried rat with a good relish if it were necessary" (147). Evaluating whether or not commensal species were in fact a food source routinely relies on the presence of butchery marks and/or evidence of burning on the remains. However, many commensal species are too small to be effectively butchered and for many species, roasting, frying, and boiling would leave little evidence on the bones. Therefore, a shift in attention from evidence of consumption on the remains of commensal species to the mechanism by which they have become incorporated into archaeological sites may prove to be a more rewarding endeavor. Given an understanding of turtle ecology, the usefulness of turtle remains as artifacts, ecofacts, and taphonomic indicators becomes apparent.

Turtles of the Chesapeake Region

Eight turtles, ranging in size from a high of 18-inches to a low of 2.5-inches in carapace length, are common to the Chesapeake Region in general and Maryland in particular. A single individual of the largest species, the Snapping Turtle, can provide up to 10-lbs of edible meat while the much smaller Box turtle provides only 1/4-lb of meat per individual. Snapping turtles, Red Bellied Turtles, and Diamondback Terrapins are highly aquatic species which feed on snails, tadpoles, and aquatic vegetation. Due to their size, diet, and aquatic nature and therefore would rarely become accidentally included in archaeological features. While painted turtles are aquatic and rarely venture from the immediate area of a pond or creek, their unusual communal basking habits render them an easy target for harvesting. As many as 50 painted turtles have been observed basking on a log at one time (Ernst and Barbour 203). Young painted turtles are carnivorous and will eat most species of plants or animals, alive or dead, and therefor may be attracted to human habitation areas by large amounts of refuse. Accidental incorporation of painted turtles into man made features is therefore possible, but not probable. It is the smaller, less palatable turtles of the Chesapeake region which spend much time in areas that prehistoric and colonial settlers sought out; areas near woodland streams, creeks, and pastures. These species forage for food, including carrion, and may be attracted to areas of human habitation, Due to their small size and difficulty thermoregulating, these species spend much of their time estivating and hibernating while burrowed in the mud near the ground surface or at depths of up to 14-cm underground.. Spotted turtles tend to remain within a muddy matrix during both estivation and hibernation while the Mud turtle prefers burrows and may remain underground year round except during the milder spring months (Ernst and Barbour). These turtles slow metabolic rate and omnivorous diet can render their flesh poisonous to humans. Accounts specific to the dangers of eating box turtles include a report that Pennsylvania miners ate box turtles (during a strike) and became ill. This account explains that the turtles may had fed on a poisonous fungus, which did not affect them but made their flesh temporarily poisonous (Ernst 1972). Another account tells of box turtles that were accidentally roasted in burning brushpiles in Mississippi and were eaten by several boys, all of whom subsequently became ill (Carr 1952). The Box Turtle in particular avoids the heat of summer days inside hollow logs, wood piles, and even under abandoned frame structures (D. Crevleing, pers comm), one mechanism by which they can become accidentally included in archaeological sites. The turtles also migrate towards shallow, muddy pools of water and vegetable debris for hibernation in these environments during winter months (Schwartz 1967). Initially burrowing just until their carapace is beneath the leaf litter, the turtle's hibernaculum gradually increases in depth as the cold weather intensifies. The protection of their hibernaculum often fails them as winter cold is the primary natural cause of box turtle death (Claussen et al 1991). Predators are the secondary cause of box turtle death. Combined with the small amount of musky flesh each of these turtle provides, potential toxicity of their flesh, and the difficulty in locating these hibernating and estivating turtles, it is probable that few were sought after soley as a food source.

Turtles in Archaeological Sites

As noted by Adler (1968) in regards to prehistoric sites in the Great Lakes region, "Turtle bones are abundant in Indian burial mounds and refuse pits. Since many turtles are large and edible, they were hunted extensively and eaten by the Indians." (147) Adler suggests the following rule for discerning turtles used for food from those used for raw material "Specimens that have been recovered from refuse pits and are unworked suggest that they were used as food." Many examples of the value of turtle shells as raw material to be made into bowls, scrapers, rattles, and ornaments exist (Graphic 2,3,4.) However, one should not necessarily assume that the turtles were acquired primarily for their meat and secondarily as a raw material source. In fact it is possible that some portion of the turtle shells used to make bowls and ornaments were obtained after the death of the turtle. Never identifying it as a possible source of turtle remains, Adler briefly mentions that "The indians created large clearings for their villages and agricultural fieldsÉmen regularly fired the woods to drive game, to improve visibility for war purposes, and to increase the supply of grass seeds. Such fires are typically fatal to terrestrial turtles and would be especially critical for juveniles with their less-protective shellsÉThe extent of these plots was enormousÉ"(274-275). Slash and burn agriculture, practiced by both Native Americans and Colonial settlers could easily eliminate an area's population of hibernating or estivating Box turtles. Some of which could easily become charred above ground or trapped in the hibernaculum. Subsequent clearing of the land for agriculture resulting in several charred or calcined turtles becoming included into a man made disposal feature as is attested to by the account of the box turtles being accidentally roasted in burning brushpiles in Mississippi, and then opportunistically eaten. Similarly, as winter cold is the primary natural cause of death for box turtles, one tilling the ground of a area inhabitated by a large number of turtles would likely uncover the remains of turtles who never emerged from their hibernaculum after a particularly cold winter. As Box turtle hibernaculums may reach depths of 14-cm, theycan easily be misinterpreted as an intentional inclusion in an archaeological site. Decompositional processes are slow to act on turtle shells due to their density. A combination of weathering, trampling, and rodent gnawing are the most effective processes for breaking down the carapace. Their high visibility and resistance to decomposition makes the collection of turtle shells as raw materials or as curiosities a common practice even today. Through this practice myself, I have discovered that turtle shells which have been extensively gnawed by rodents can take on the appearance of man made artifacts. In fact a recently collected box turtle shell is remarkable similar to fragments of a box turtle recovered from a midden area of colonial Belair Mansion.

Case Study

The stratigraphic profile of a recently excavated colonial tavern cellar, suggests multiple successive large in-filling events have resulted in the archaeological assemblage. Ceramic and tobacco pipe bore dates suggest a slight but insignificant time shift between strata. Among the fauna identified from the feature are three species of turtles (See Table 3). One is a plastron fragment from a Diamondback Terrapin (Malaclemmys terrapin terrapin); another is a carapace fragment from a Snapping Turtle (Chelydra serpentina). The third is a large number of fragments from an indeterminate number of Box Turtles (Terrapene carolina carolina), both carapace and plastron. Mending resulted in the identification of a single, nearly complete male box turtle. The completeness of the remains, their proximity to one another, and the lack of any identifiable butchery markings, suggested that the box turtle was an ecofact and not the remains of a tavern meal. It is therefore plausible that that the deposition of fill into the tavern cellar feature ceased well enough before October to allow for water and vegetable debris, such as fallen leaves, to accumulate. This period of time could have been as short as a week or as long as a year or more. The box turtle then buried itself in this shallow layer of mud and leaves and began his hibernation. Unless the turtle died of natural causes, the infilling of the feature must have resumed before the turtle awoke from his sleep in February of the next year. Alone, the information provided by the box turtle is only slightly more than a taphonomic hypothesis. The stratigraphic profile of the feature does, however, suggest an infilling hiatus of a duration that would allow for significant settling. A re-examination of the ceramics from the feature revealed a shift in prominence from plates with one motif, found below this turtle, to another, found above it. Tobacco pipe bore analysis also showed a shift from pipes of a size 5 to a size 4 pipe bore, dating from these pipes placed the fill below the turtle to approximately 1740 while the fill above the turtle dates to 1750.

Conclusion

Turtles, like all commensal species may provide valuable insight into the depositional history of archaeological features. While many commensal species in fact may or may not have been consumed, reliance on butchery marks and burned bones can be misleading. Confusion over the likelihood of that turtles were consumed by a sites inhabitants appears to hinder interpretations of some features and even certain archaeological sites. For example: A Maryland site survey form reads "except for a turtle shell fragment, no evidence of in situ deposits" was found. Similarly, a report on the faunal assemblage from a colonial well in Virginia reads: "Many aspects of the sample suggested that not all the material present was of a subsistence nature. Most species were probably incidental with the possible exception of the turtles, which could have been eaten" (Barber 1976). Emphasis away from the primary assumption of consumption and towards the analysis of commensal species ecology and taphonomy can provide supplemental insight into the formation processes of these sites and features.