North American box turtles belonging to the genus Terrapene have been icons of turtle research and conservation for more than a century (Surface 1908). These small terrestrial and omnivorous turtles are distributed in the Unites States and Mexico and occur in habitats ranging from moist humid tropical forests, deserts, to hardwood forests (Dodd 2002). Unfortunately, all extent species face serious conservation threats, and these threats are as diverse as the habitats they occupy. Population bottlenecks, illegal trafficking, and climate change are just a few (Kuo and Janzen 2004; Gong et al. 2009), and have elevated the conservation status of 3 species as vulnerable (Terrapene carolina; van Dijk 2011), near threatened (Terrapene ornata; van Dijk and Hammerson 2011), and endangered (Terrapene coahuila; van Dijk et al. 2007) by the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. The fourth species, Terrapene nelsoni, however, remains largely unknown to science and considered data deficient by IUCN (Tortoise and Freshwater Specialist Group 1966).

Terrapene nelsoni, or the Sierra box turtle, is 1 of only 3 Terrapene species that are distributed in Mexico and has 2 recognized subspecies, T. n. nelsoni and T. n. klauberi (Shaw 1952). These subspecies are distributed throughout the Sierra Madre Occidental mountain chain, with T. n. klauberi distributed in Sonora, southwestern Chihuahua, and Sinaloa, and T. n. nelsoni in Sinaloa, Nayarit, and Jalisco (Turtle Taxonomy Working Group 2017). Throughout this range, T. nelsoni has been documented at elevations ranging from 400 m above sea level (masl) in tropical dry forest to > 1500 m in pine–oak (Pinus spp.–Quercus spp.) forest (Legler and Vogt 2013). Beyond the handful of locality information that exist on T. nelsoni, little is known about their natural history.

Information on the natural history of T. nelsoni is needed because deforestation, climate change, and illegal trafficking are serious threats throughout the Sierra Madre Occidental mountain chain. For example, tropical dry forests in Mexico, which characterizes the lower elevations of the Sierra Madre Occidental, lost > 71% of its original vegetation cover by year 2010 and < 2% of the remaining TDF falls within protected areas (Portillo-Quintero and Sánchez-Azofeifa 2010). Future climate models predict that the forests of Sierra Madre Occidental will be significantly reduced by year 2070 (Prieto-Torres et al. 2016). In addition, illegally collecting and trading freshwater and terrestrial turtles is not heavily enforced in Mexico, and despite all Mexican box turtles being classified as appendix II CITIES (Macip-Ríos et al. 2015), permits to collect, reproduce, and legally sell turtles are easier to obtain for species like T. nelsoni because little is known about their natural history. Thus, an immediate priority is to understand the natural history of T. nelsoni and to assess their conservation status.

Our goal was to provide a first look into the natural history of T. n. klauberi in southeastern Sonora. To do this, we conducted visual encounter surveys for T. n. klauberi and tracked select individuals with radiotelemetry periodically between July 2018 and April 2020 in the Monte Mojino reserve in southeastern Sonora. We present data on the occurrence of turtles in different vegetation types, home range size, demography, thermal biology, sexual dimorphism, and provide a preliminary assessment of their diet.

METHODS

Study Site. — This study was conducted in the Monte Mojino reserve, located within the Sierra de Alamos–Río Cuchujaqui federal protected area in southeastern Sonora, Mexico. This reserve and protected area represent a cross-section of the Sierra Madre Occidental mountain chain that runs from northern Mexico in the states of Sonora down south to Nayarit. Monte Mojino is representative of this mountain chain because it has the same elevational gradient that characterizes the western slope of the entire mountain chain, which starts at 300 masl in tropical dry forest vegetation, and gradually reaches to about 1300 masl where pine–oak forest is the dominant vegetation. Terrapene nelsoni has been observed along this gradient at elevations ranging from 400 to 1600 masl (Legler and Vogt 2013), so we sampled turtles in 3 vegetation types. Two sites were in the tropical dry forest at 300 masl (Figs. 1C and 2), another site was at 1000 masl in a grassy oak savannah (Figs. 1B and 2), and the third site was at 1300 masl in pine–oak forest (Figs. 1A and 2). These field sites have a prolonged dry season that can last 6–9 mo, followed by a short wet season (June–September; González-Elizondo et al. 2012). All field sites experience between 300 and 1200 mm of precipitation per year (González-Elizondo et al. 2012). Average monthly temperatures in the tropical dry forest averages 23.9°C–35.6°C (González-Elizondo et al. 2012). Monthly average temperatures of grassy oak savannah and pine–oak forest are not available, but temperatures recorded at the field station in pine–oak forest in 2017 ranged between 2.1°C and 32.7°C and averaged 16.6°C (L. Lozano, pers. comm., September 2019). Understory vegetation in the tropical dry and pine–oak forests varies from open to very dense with many species of shrub, vines, and cacti. In grassy oak savannah, grass is the dominant understory vegetation with intermittent patches of agave plants. There are very few canopy gaps in tropical dry and pine–oak forest, but canopy gaps, or small grassy meadows, are a normal feature of grassy oak savannah.

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Sampling Protocol and Sampling Periods. — We located turtles using visual encounter surveys, which consist of walking in a loose grid fashion with 2–5 people walking about 3 m apart from each other through potential turtle habitat. The total area surveyed encompassed an estimated area of 23 ha in the pine–oak forest, 17 ha in grassy oak savannah, and 42 ha in tropical dry forest. The surveys in tropical dry forest were split between two localities that were 2.7 km apart. These surveys were conducted during the short rainy season that occurs from June to October and weather data were not recorded during surveys. The start and end times, number of people, and number of turtles encountered were documented for each survey. The sum of search hours for each survey was multiplied by the number of people to calculate total person-hours per survey. The sum of these person-hours per survey for each vegetation type was divided by the number of turtles found in each vegetation type to calculate the estimated number of person-hours needed to find one individual turtle (hrs/individual). We sampled each sampling site at irregular intervals between July and August 2018. Then, starting in May 2019 we began conducting searches in tropical dry forest at least twice per month to locate more individuals in lower elevations and these surveys continued through March 2020. Lastly, in August 2019, surveys were conducted over the course of 3 wks in grassy oak savannah and pine–oak vegetation types.

Home Range Size and Microhabitat Use. — To estimate home range and document microhabitat usage, we radio-fitted a subset of turtles found during surveys. Turtles were equipped with 15-g Holohil RI-2B radios (Holohil Systems, Ltd, ON, Canada) on their posterior costal scutes using epoxy putty, and then monitored with a Telonics TR-4 receiver and rubber ducky antenna (Telonics, Inc, AZ). Each time we located a turtle in the field, we recorded date, time, Global Positioning System (GPS) location, activity (e.g., active walking or inactive), and microhabitat when inactive. If the turtle was active, we did not record any microhabitat data. We also did not record macrohabitat data when tracking turtles. All GPS locations are omitted to protect the species from illegal poaching.

We tracked radio-fitted turtles between August 2018 and March 2020. We tracked these turtles sporadically because of our inability to arrive at field sites. Thus, our data can only be used to provide a baseline of home range for this species. In August 2018, we put a radio on 1 male (no. 5) in the tropical dry forest, 2 males (no. 2 and 8) in pine–oak forest, and 1 female (no. 3) in pine–oak forest. These first individuals were monitored over the course of 3 wks during August 2018, 3 d in April 2019, and 1 wk in August 2019. Three additional individuals (no. 27, 28, and 29) were located in the tropical dry forest in May 2019, equipped with radios, and then tracked until April 2020. Individual no. 29 was only tracked through July 2019 until his radiotransmitter fell off.

Home range was estimated using the 100% minimum convex polygon (MCP) technique and was executed using the ‘mcp' function in the ‘adehabitatHR' package in Program R (Calenge 2006). Home range size between vegetation type and sex was tested for significance using a Mann-Whitney U-test (or Wilcoxon ranked sum test) because these data were not normally distributed. This was executed using the ‘wilcox.test’ function in R Statistical Software version 3.6.1 (R Core Team 2019).

Body Temperature. — To gain insight into the thermoregulatory behavior of T. n. klauberi, we used a Schultheis “quickreading” reptile thermometer (Miller and Weber, Inc, NY) to take body temperatures of turtles and their immediate surroundings when encountered active in the field. Body temperatures (T_b) of turtles were taken with a quickreading thermometer by inserting it approximately 10 mm into the cloaca of the turtle for about 15 sec and noting the temperature. After taking T_b, 3 environmental temperatures were taken in a similar fashion at the location where the turtle was found. These temperatures were taken 1.5 cm below the surface of the soil (T_s), 10 cm above the surface of the soil (T₁₀), and 150 cm above the surface of the soil (T₁₅₀).

We used an independent sample Student t-test with the ‘t.test' function in Program R to determine whether there are significant differences in T_b, T_s, T₁₀, and T₁₅₀ between males and females. The assumption of normality of each variable was assessed using the Shapiro-Wilks test with the ‘shapiro.test' function in R, and the assumption of homoscedasticity was assessed visually using boxplots. If these assumptions were not met, then a Mann-Whitney U-test was used as a nonparametric alternative. Furthermore, to determine if turtles regulate their body temperatures or conform to ambient temperatures, we used paired Student t-tests with the ‘t-test’ function in R and test differences between T_b – T_s, T_b – T₁₀, and T_b – T₁₅₀ without considering sex. The assumptions of normality and homoscedasticity of these paired t-tests were also assessed using the Shapiro-Wilk test and visually inspecting boxplots.

Sexual Dimorphism in Morphology. — All turtles that were encountered in the field were given a unique number using the notch system (Cagle 1939) and then measured. The standard morphological measurements taken for each individual include carapace length (CL, nuchal scute to cleavage between supracaudal scutes), plastron length (PL, intergular scute to cleavage between anal scutes), plastral lobe width (Lobe, length of seam that connects femoral and abdominal scutes), carapace width (CW, width between 5th and 6th marginal scutes), and shell height (SH, maximum vertical height from plastron to carapace). Limb and head characteristics were measured for select adult individuals that were temporarily brought to the laboratory for a different study in August 2018 and August 2019. Limb characteristics measured include: antebrachium length (Ante, apex of elbow to wrist crease), manus length (Hand, middle of the wrist crease to distal end of 3rd digit where skin meets the nail), crus length (Crus, apex of knee to apex of heel), pes length (Foot, apex of heel to distal end of 3rd digit where skin meets nail), and surface area of interdigital webbing of pes (RearWeb, area of webbing between 2nd and 3rd toe). Interdigital webbing area was calculated by multiplying the width and length of the interdigital webbing and dividing by two. Head characteristics measured include head width (HW, widest part of the skull), head length (HL, premaxilla to posterior edge of supraoccipital), and head height (HH, highest part of the skull at posterior end of jaw). All measurements were measured to the nearest 0.1 mm using dial calipers.

To provide insight into the sexual differences of this species, we compared linear measurements of the limbs, shell, and head of males and females. Not all morphological measurements were taken on all individuals observed because characteristics of the limbs and head were only taken on select individual that were temporarily brought to the laboratory for a different study in August 2018 and August 2019. For this, there are different sample sizes among the morphological variables that we investigated. We used Student t-tests to compare significant differences of each morphological variable between males and females using the ‘t-test' function in R (R Core Team 2019). The assumption of normality was measured using the Shapiro-Wilk test and homoscedasticity was visually assessed using boxplots. Most morphological variables are correlated to body size, so we also compared significant differences in each morphological variable after removing the effect of body size. To do this, we used the residuals calculated from regressing each morphological variable on CL. These linear regressions were calculated using the ‘lm' function in R and are referred to as “size-free variables”. The assumptions (normality and homoscedasticity) of these linear models were assessed using the diagnostic plots for the ‘lm’ function in R before proceeding with Student t-test. The original nontransformed morphological variables are referred to as “original variables”. We also calculated the sexual size dimorphism index for T. n. klauberi using CL. Sexual size dimorphism index is a standard measure used to quantify deviations in sexual size dimorphism in a population, and is calculated by dividing the CL of the larger sex by the smaller sex and assigning a negative sign to these values when males are the larger sex (Lovich and Gibbons 1992). Lastly, many of the individuals we encountered in the field had severe damage to their marginal scutes, and to determine whether the frequency of damage is different between the sexes, we calculated the proportion of males and proportion of females that were observed with such damage.

Only descriptive statistics were used to assess abundance in different vegetation types, microhabitat use, and population structure. Whereas, direct observations were used to preliminarily assess diet. All statistical analyses were scrutinized to an α level = 0.05.

RESULTS

Sampling Effort in 3 Different Vegetation Types. — We conducted 89 surveys on 68 different days throughout the study period with groups of 1–5 people (x̄ = 2.6 people) and surveys lasting between 1 and 5 hrs (x̄ = 2.4 hrs). There are more surveys than days that we conducted surveys because when we were in the pine–oak vegetation type, we conducted 1–3 surveys/d. Terrapene nelsoni klauberi are more common in pine–oak, then grassy oak savannah, followed by tropical dry forest vegetation type. The sum of our search effort totaled 144.2 hrs and 41 turtles in pine–oak, 29.75 hrs and 4 turtles in grassy oak savannah, and 397.1 hrs and 4 turtles in tropical dry forest. This indicates that it takes an estimated 3.5/person-hours (hrs/turtle) to find T. n. klauberi in pine–oak forest, 7.4 hrs/individual in grassy oak savannah, and 99.3 hrs/individual in tropical dry forest. An empty shell of an adult individual was found in the tropical dry forest in July 2018 and not included in this estimate.

Home Range Size. — Over the course of this study, 7 individuals that were located in tropical dry forest (4 males and 3 females) and pine–oak forest (2 males and 1 female) were equipped with radiotransmitters (Fig. 3). No individuals in grassy oak savannah were tracked because this vegetation type was not close enough to a field station where we could consistently go to this vegetation type. Home range sizes ranged from 0.41 to 3.09 ha (Table 1; Fig. 3). Average (± SD) home range size was 1.76 ± 1.2 ha for all individuals, 1.42 ± 1.4 ha in pine–oak forest, and 2.02 ± 1.2 ha in tropical dry forest. Average male and female home range size was 1.55 ± 1.2 and 2.05 ± 1.42 ha, respectively. There were no significant differences in home range size between vegetation type (Mann-Whitney U-test; W = 5, p = 0.857) or sex (W = 6, p = 1.00). Turtles that were observed inactive during telemetry surveys (n = 40) were found in rock shelters (n = 14), woody debris (n = 10), tree shelter (n = 9), leaf litter (n = 6), or soil burrows (n = 1). Microhabitat when turtles were active was not recorded.

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Table 1. Summary of Terrapene nelsoni klauberi that we tracked with radiotransmitters between 2018 and 2019. Pine–oak = pine–oak forest; TDF = tropical deciduous forest; n = locations per individual; CL = carapace length (mm); MCP = 100% minimum convex polygon. No individuals were tracked in grassy oak savannah.

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Population Characteristics. — Our sample of T. n. klauberi in the Monte Mojino reserve is composed of mainly adults (Fig. 4). We captured 49 unique individuals—4 were juveniles, 27 were female, and 18 were male (1♂:1.5♀). Of the 49 turtles captured, only 5 adults were found in the tropical dry forest, 1 of these individuals was dead, and the rest had eroded growth rings suggesting that they were very old individuals (Fig. 1F). The remaining turtles were found in grassy oak savannah (n = 4) or pine–oak vegetation (n = 41). Only 1 juvenile was found in grassy oak savannah and 3 were found in pine–oak forest; the rest of the individuals we located in these vegetation types were adults.

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Body Temperatures. — We collected 28 body temperatures of 10 males and 18 females and the environmental temperatures of the locations where they were encountered. All but one of these body temperatures (male no. 5) were taken on individuals in pine–oak vegetation. When comparing T_b, T_s, T₁₀, and T₁₅₀ between males and females, all data were normal and homoscedastic except for the T₁₅₀ measurements of males, which were not normally distributed. There was significant difference between sexes in T_b (Student t-test; t = –2.21, p = 0.018), but not T_s (t = –1.56, p = 0.065), T₁₀ (t = –1.58, p = 0.063), or T₁₅₀ (Mann-Whitney U-test; W = 54.5, p = 0.267; Table 2). Results from the paired ttests show that in our observations, T. n. klauberi had significantly higher T_b than T_s (t = 8.92, p < 0.001), T₁₀ (t = 5.87, p < 0.001), and T₁₅₀ (t = 5.63, p < 0.008; Table 2). T_b was an average 3.34°C above T_s, 2.24°C above T₁₀, and 1.84°C above T₁₅₀.

Table 2. Mean (± SD) body and environmental temperatures (°C) for males, females, and all individuals. T_b = cloacal temperature; T_s = 15 mm below the surface of the soil; T₁₀ = 10 cm above the surface of the soil; T₁₅₀ = 150 cm above the surface of the soil.

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Sexual Dimorphism in Morphology. — Male and female T. n. klauberi do not differ in CL (Table 3) and have a sexual size dimorphism index of 1.01. When comparing the nonstandardized morphological variables of the limbs, shell, and head, we found that males have a smaller plastral lobe, more compressed shell, and longer head (Table 3). Removing the effect of CL from these variables showed similar results, and that males weigh less, have a smaller plastral lobe, more compressed shell, and longer head (Table 3). A total of 14/45 (31%) of the individuals that we observed had moderate to severe damage to their anterior marginal scutes. Of the male individuals, 8/18 (44%) had damage to their scutes, and 6/27 (22%) females had damage to their marginals. All of the turtles with damage to their scutes were located in pine–oak forest.

Table 3. Summary of the comparison of morphological variables between males and females of Terrapene nelsoni klauberi in Monte Mojino Reserve. Original variables correspond to raw measurements (mm) taken for each morphological variable and size-free variables represent residuals of variables after being regressed against CL to remove the effect of body size. Sample size, mean values for each variable in males and females, tstatistic, and p-values are displayed. Bold font indicates p < 0.05. CL = carapace length; PL = plastron length; Lobe = plastral lobe width; MW = marginal width; SH = shell height; Ante = antebrachium length; Hand = manus length; Crus = crus length; Rear foot = pes; HW = head width; HL = head length; HH = head height.

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Diet Observations. — We observed turtles foraging 15 times in pine–oak forest and 5 times in tropical dry forest. Six of our observations consist of finding T. n. klauberi foraging in horse manure. Turtles that were found foraging in horse manure were located within the 26-ha tract of land that was surveyed in the pine–oak forest, and this horse manure is from four horses that are allowed to pasture in this area. It appears (not directly observed) that turtles are targeting several species of dung beetle that process the manure, one of which has been identified as Phanaeus amithaon (subfamily: Scarabaeinae). We also found turtles on 2 occasions at waste piles that are created by leaf-cutter ants (Atta sp.), apparently foraging on beetles. Patent-Leather beetles (subfamily: Passalinae) have been the only type of beetle observed at these waste piles. Furthermore, on 4 occasions we observed turtles foraging on 2 species of mushroom—Rusela sp. and possible Amanita sp.—and 2 of these observations were made on the same mushroom by 2 different individuals on consecutive days. The remaining 6 observations consist of observing turtles forage on unidentifiable herbaceous vegetation (n = 4), grass (n = 1), and wildflowers (n = 1).

DISCUSSION

Our study provides a preliminary assessment of the natural history of T. n. klauberi by providing baseline data on local abundance, demography, and home range. We also document sexual differences in morphology and behavior between males and females that have not been documented in other turtle species or populations. Lastly, we provide observations of diet items that T. n. klauberi was observed foraging on in the wild.

Finding T. n. klauberi at elevations ranging from 300 to 1300 masl corroborates previous observations (Legler and Vogt 2013), but finding that this species is extremely rare at lower elevations (300 masl) and more common at higher elevations (1000 and 1300 masl) has not been previously documented. This observation might represent the natural distribution and abundance of T. nelsoni at different elevations. However, an expected outcome of climate change is a shift in species distribution to higher elevations (Chen et al. 2011). Thus, it is possible that the rarity of T. n. klauberi at lower elevations could reflect population declines at lower elevations due to climate change. Although these differences in abundance at elevations could reflect their natural abundance, it is important to recognize this possibility because anecdotal reports from local people in the Monte Mojino reserve suggest that prominent stands of oak trees (Quercus tuberculata) that are located at the top of some hills in the tropical dry forest have been disappearing over the past few decades. These oak stands are located in cooler microhabitats, and the locals attribute the disappearance of these trees to increasing temperatures and longer dry seasons. Similarly, locals attribute the establishment of several tropical dry forest tree species at higher elevations in the pine–oak forest to warming temperatures. Therefore, even if our findings represent the natural abundance of this species and not declining populations due to climate change, the observations from locals that climate change could be affecting vegetation in this area merits future research to determine whether populations of T. n. klauberi are being affected. Accomplishing this will require more surveys at intermediate elevations to determine how the abundance and distribution of T. n. klauberi changes from lower elevations in the tropical dry forest to pine–oak forest.

The average home range size of T. n. klauberi of 1.76 ha is similar to that observed in a population of Terrapene ornata luteola (1.6 ha; Nieuwolt 1996) and in a population of T. c. carolina (1.88 ha; Donaldson and Echternacht 2005), but smaller compared with other studies (2.68–4.04 ha; Refsnider et al. 2012; Kapfer et al. 2013). Therefore, even though our results are preliminary and might not be representative of this species, these results seem to fall in the range of observed home ranges in other species of Terrapene. Likewise, the population structure of T. n. klauberi seems to be similar to some populations of Terrapene in that it is dominated by adult individuals (Dodd 2002). The female-biased sex ratio of 1:1.5 that we observe in T. n. klauberi is similar to some populations of T. ornata (Legler 1960; Doroff and Keith 1990), but is uncommon among other populations of Terrapene that usually have sex ratios that are closer to 1:1 or male-biased (Dodd 2002). We hope that future investigation with T. nelsoni will provide a more comprehensive understanding of home range size and population structure, especially at lower elevations where turtles seem to be rare. An additional future priority of this species should be determining how weather, season, vegetation, age class, or sex could affect the detectability of this species during surveys.

We found that active T. n. klauberi had an average body temperature of 28.15°C ± 2.73°C. Similar body temperatures of active turtles have been observed in T. o. luteola in Arizona (Plummer 2003), and our observations also fall within the proposed optimum temperature for locomotor activity in T. c. carolina (24°C–31.9°C; Adams et al. 1989). That turtles regulate temperatures an average 1.84°C–3.34°C above environmental temperatures suggests that both males and females actively thermoregulate to maintain their body temperature above ambient temperatures (Huey and Slatkin 1976). The opposite has been observed in T. c. carolina, which have been shown to conform to environmental temperatures (Parlin et al. 2017), making it unclear what determines the tendency for turtles to actively thermoregulate or conform to surrounding environmental temperatures. Thermoregulation in Terrapene merits further research, and the observation that male T. n. klauberi have higher body temperatures than females suggest that there could be sexual dimorphism in thermoregulatory behavior.

One of the most interesting results of our study is that males and females are not significantly different in CL, but differ in other morphological characteristics, including head length. Such differences in head length have not been observed in other terrestrial turtle populations. However, it has been reported in the genus of aquatic turtles, Graptemys, in which some species have evolved megacephalic heads that are correlated to differences in diet (megacephalic species consume more mollusks; Lindeman 2000). Closer investigation of diet in T. n. klauberi is needed to determine if differences in head size are attributed to differences in diet or if there are other factors that explain the sexual differences in head size.

We found that 30% of all the turtles we observed, including 44% of all males and 22% of all females, had moderate to severe damage on their anterior or marginal scutes. All of the turtles with marginal damage were adults in pine–oak forest, which could indicate higher levels of predation in this vegetation type. However, the tendency for this damage to be on the anterior marginal scutes is inconsistent with the damage that we have observed in other terrestrial species that we study in the tropical dry forest ecosystem, in which damage seems to be randomly distributed across different regions of the shell (Rhinoclemmys rubida, Rhinoclemmys pulcherrima, Terrapene yucatana, and Gopherus evgoodei; T. Butterfield, pers. obs.). This high frequency of damage, and the fact that male T. n. klauberi have very large heads, makes it seem like this damage could be inflicted by other males over time if biting is an important part of their natural history. Whether this damage is from increased predation or from other turtles, determining the reason for a high frequency of damage to the marginals of T. n. klauberi and the reason that males have larger heads should be a research priority for this species.

The diet items that we observed T. n. klauberi foraging on (beetles, mushrooms, herbaceous vegetation, grass, and wildflowers) have also been observed in other studies in the Terrapene genus (Dodd 2002). Interestingly, however, the majority of our diet observations were made in pine–oak vegetation of turtles apparently scavenging through horse manure, and it is unclear how an artificial food source such as manure could influence the dynamics of turtle populations. It is possible that this could contribute to T. n. klauberi being more abundant at our field site in pine–oak vegetation, but further investigation of diet at similar sites that are not regularly used by horses is needed to determine whether this is the case.

Together, these findings provide an outline of the natural history of T. n. klauberi and in many ways parallel findings from previous studies on other Terrapene sp. However, the wide range of elevations and vegetation types in which T. nelsoni occur seems to be a unique and important aspect of their natural history. For this reason, in order to assess the conservation of T. nelsoni in other parts of its geographic distribution, a priority should be providing a basic understanding of how their abundance and distribution changes from lower to higher elevations and among different vegetation types. Such an understanding could help prioritize where to conduct future surveys for this species in different parts of its geographic distribution. Our study suggests that locating field sites in pine–oak vegetation at elevations > 1000 masl is a good starting point for such surveys.