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16 July 2026

14 Pages

Of Pigs and Pillars: Wild Pigs (Sus scrofa) Impair a Critical Functional Group of Headwater Streams, Threatening an Important Component of the Environmental Pillar of Sustainability

and
Department of Natural Sciences, Piedmont University, Demorest, GA 30535, USA
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Author to whom correspondence should be addressed.
Sustainability2026, 18(14), 7269;https://doi.org/10.3390/su18147269
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Abstract

Comprising the greatest proportion of stream networks, headwater streams provide critical ecosystem services to entire river networks by sustaining water quality and biodiversity as well as controlling floods and groundwater recharge. As such, they are important contributors to the environmental pillar of sustainability. Unfortunately, they are also among the most vulnerable ecosystems. In Appalachian headwater streams, larval salamanders represent a critical functional group because of their strong influence on ecosystem function. Wild pigs (Sus scrofa) rank among the most notorious invasive species, with widespread, negative impacts on native habitats and biodiversity. We tested the impacts of wallowing by wild pigs on the salamander larval community in Appalachian headwater streams in northeastern Georgia and found a significant drop in both numbers and diversity of larvae in wallows. Because downstream networks and the communities that depend upon them rely on healthy headwater streams, understanding exactly how the impairment of this functional group by wild pigs impacts energy flow, nutrient cycling, carbon sequestration, and water quality requires further investigation.

1. Introduction

Humans cannot depend solely on their own activities to ensure a safe and equitable future [1]. Such a future depends on a complex of factors that have been metaphorically described as the three pillars of sustainability: economic, social, and environmental [2]. Frequently pictured as a Venn diagram [2], these three pillars overlap and interact in a complex manner through a series of feedback loops [3,4] and tradeoffs [5,6] so that effects in one area can have profound repercussions for the others [7]. Specifically regarding the environmental pillar, there has been growing recognition not only of the biophysical foundation upon which human systems are built, but also the extended value of healthy natural systems as providers of natural capital and essential ecosystem services that support human societies and economies [8].
One of the focal points of the environmental pillar of sustainability is the critical value of biodiversity. The ecosystem services provided by nature depend directly on the diversity of the ecosystem’s living parts [9,10,11,12]. For example, food webs play an important role in carbon sequestration, which mitigates the effects of climate change [13,14,15,16]. The more complex the food web, the more likely it is to be able to sustain itself and continue to play this vital role [17].
Headwater streams represent an ecosystem characterized by such complex food webs, and due to their ubiquity and the ecosystem services they provide, are among the most important natural systems [18]. Likened to the fine branches of the human respiratory system, headwater streams undergird the health of entire river networks and are thus critical to sustaining an overall healthy landscape [18]. Comprising as much as three-quarters of river catchments [19], headwater streams provide valuable ecosystem services by protecting water quality [20], controlling surface flow and groundwater recharge [21], contributing organic matter for downstream food webs [22,23], and supporting high levels of biodiversity and endemism [24,25,26,27]. However, similarly to the tiny alveoli and bronchioles of a human lung, headwater streams are small and isolated and are thus highly vulnerable to degradation [28,29]. Unfortunately, a general lack of appreciation of their importance (e.g., the 2023 decision by the U.S. Supreme Court that removed their legal protection) only adds to their vulnerability [30].
Like other ecosystems, headwater streams are threatened by invasive species, which have long been recognized as threats to ecosystem integrity [31,32,33,34]. By damaging biodiversity and interrupting food webs, invasive species threaten a critical component of the environmental pillar of sustainability [35,36]. Wild pigs, also called feral swine (Sus scrofa), are among the most notorious invasive species across the globe [37], having negative impacts ranging from the disruption of native habitats [38] and the loss of biodiversity [37,38,39] to economic costs to agriculture as well as threats to water quality and human health [40,41,42,43,44]. One of the most important ecological effects results from the role of wild pigs as ecosystem engineers, whereby they change habitat characteristics through rooting and wallowing, thereby indirectly affecting resident organisms [40,45]. Wallowing in particular is a common behavior by which wild pigs root out a depression within a wet substrate in which individuals lie, wriggle, and coat themselves with mud for thermoregulation [46], although other functions such as scent-marking may be involved as well [47].
Small, isolated wetland habitats characterized by high levels of endemism are particularly vulnerable to disruption. Headwater streams clearly represent small, isolated systems with high levels of endemism [26]. They are thus highly vulnerable to degradation [27], including the destructive activities of wild pigs [44,48]. However, the effects of wild pigs on aquatic communities, including those occupying headwater streams, have been scarcely studied [45].
Major components of aquatic communities are amphibians, which include frogs, salamanders, and caecilians. As a taxonomic group, amphibians are themselves important in providing ecosystem services and thereby contribute to overall sustainability through direct or indirect impacts on biodiversity, ecosystem health, and human well-being [49]. Their place within food webs is particularly important [49,50,51]. Because of their dependence on cutaneous respiration and both aquatic and terrestrial habitats, amphibians face a myriad of threats, including invasive species [52]. They in fact represent the most endangered group of vertebrates [53] with more than 40% of the planet’s species in danger of extinction [51].
In headwater streams across the southern Appalachian Mountains of the U.S., larvae of lungless salamanders (family Plethodontidae) represent vital components because of their high density and productivity [54,55]. Aquatic salamander larvae are particularly important as mid-trophic-level predators, significantly affecting the structure of invertebrate communities [56] as well as energy flow and nutrient cycles within the stream ecosystem [57,58,59,60]. Because they feed on allochthonous food sources, they also contribute to energy and nutrient transfer across the aquatic–terrestrial interface [61]. Because of their ecological roles, plethodontid salamander larvae represent a critical functional group (sensu Brondel [62]) in headwater streams. Moreover, because larval plethodontids become semi-aquatic or terrestrial upon metamorphosis, they are necessary because as adults, they carry out these same functions in the surrounding riparian forest [63].
The direct impacts of wild pigs on salamanders have rarely been studied. Although wild pigs prey on amphibians, evidence suggests that wild pigs eat frogs more than they do salamanders [64,65]. Therefore, the more likely impact that wild pigs have on salamanders is from disruption of their habitat. Researchers have speculated that wild-pig activity has resulted in habitat changes that have contributed to declines in certain endangered salamander species [66,67,68]. However, we are aware of only a single study that showed a direct relationship between wild-pig activity and decline in salamander densities, and less than 5% of the salamanders observed in that study were larvae [69]. As a result, the effect of wild pigs on larval plethodontids, particularly in headwater streams, has gone virtually unstudied.
Wild pigs were first introduced into North America during the period of European exploration and colonization [70] with a long history in the southeastern U.S. [43,71]. They occur within the drainage basin of the Savannah River, which forms the boundary between the states of Georgia and South Carolina [72,73]. Among the tributaries of the Savannah River which supports populations of wild pigs is the Tugaloo River, which forms from the confluence of the Tallulah and Chattooga rivers along the boundary between northeastern Georgia and northwestern South Carolina. Small streams throughout the region are rich in plethodontid salamander diversity [74,75,76,77] and provide habitat for at least one species of conservation concern, the Patch-nosed Salamander, Urspelerpes brucei. Activity by wild pigs has been documented in headwater streams in the region, including in resident streams of U. brucei [78,79]. Because of the importance of larval-salamander communities to healthy streams and the potential threat of wild pigs, we tested whether wild-pig activity has a direct effect on the number and diversity of plethodontid larvae in headwater streams within the catchment of the Tugaloo River.

2. Materials and Methods

We collected data during late March and early April of 2026. We chose headwater streams that flow either directly or indirectly into the Tugaloo River in Stephens County, Georgia (Table 1; Figure 1). This area, though similar in elevation to the adjacent Piedmont ecoregion, is characterized by considerable topographic relief that creates montane microclimates and, as a result, is classified within the Blue Ridge ecoregion [80].
Table 1. Locations of wallowing sites of wild pigs (Sus scrofa) in headwater streams in the Tugaloo River basin in Stephens County, Georgia, USA. Each location may have several wallowing sites, and each wallowing site may have more than one actual wallow.
Figure 1. Map of wallowing sites of wild pigs (Sus scrofa) in northeastern Georgia, USA. Each dot represents one or more wallowing sites. Size of dots represents relative surface area occupied by wallows. Inset map of USA shows location as white dot. White lines represent roads, and blue ones represent waterways.
We focused on pig wallows because of the nature of stream disruption. To find wallows, we walked up every accessible small stream in the study area until we found signs of wild-pig activity. We identified wallows by a combination of traits: the presence of pugmarks; clear signs of rooting activity, either within or adjacent to the stream; and the distinctive oval-shaped, scooped-out, pig-size depression characteristic of wallows.
We considered several adjacent wallows to represent a single wallowing site but wallows that were at least 25 m apart to represent different sites. Using a 1 m2 quadrat made of polyvinyl chloride (PVC) pipe (Charlotte Pipe & Foundry, Charlotte, NC, USA), we estimated the area occupied by each wallowing site and then marked off a section of the same size of the nearest undamaged portion of stream as a control. While some inequality between wallow and control sites in terms of water volume may have existed because of differences in water depth caused by making the wallow, our approach accounted for the amount of stream affected by the wallow.
Prior to collection, we noted the condition of both wallow and control sites, specifically whether the water was visibly flowing (current) or not (pool). To avoid inter-investigator sampling variance, the same person (CDC) used a hand net to collect salamander larvae. All parts of both wallow and control sites were thoroughly searched with forcefully agitating, disruptive sweeps through and beneath silt, rocks, and plant roots. Searching continued until three thorough sweeps of the entire area no longer turned up salamanders. We identified each to species on site.
In two different cases, we could not identify larvae to species because of the presence of coexisting, cryptic species whose larvae are difficult or impossible to distinguish without genetic analysis. One case involved cryptic species of the genus Desmognathus, including the southern black-bellied salamander, D. amphileucus, and the dwarf black-bellied salamander, D. folkertsi [81]. The other involved Eurycea species, including the southern two-lined salamander, E. cirrigera, and the Blue Ridge two-lined salamander, E. wilderae [82]. We designated these larvae as Desmognathus sp. and Eurycea sp., respectively. We also recorded all other amphibians (i.e., metamorphosed salamanders, frogs, tadpoles) or amphibian eggs collected. Immediately following identification, we released all individuals back into their respective locations. All specimens were collected under permits issued by the state of Georgia (126977097) and the US Forest Service (CHA2316).
To test for a difference in the number of plethodontid larvae between wallows and controls, we used the Wilcoxon signed-rank test as a non-parametric, pairwise analysis for all comparisons. We chose a non-parametric analysis because our data were integers, and thus not normal, or because they failed a Shapiro–Wilk test of normality. To test for a difference in larval diversity, we used count data from sites in which there was at least one salamander in both wallow and control sites. Using an online calculator (https://www.omnicalculator.com/ecology/shannon-index; accessed 11 April 2026), we generated a Shannon Diversity Index [83], which is commonly used to measure species diversity in ecological systems [84]. We further tested for differences in species richness. To estimate the effect on standing stocks of nutrients within the streams, we used estimates of biomass (dry mass), total carbon (C), nitrogen (N), phosphorus (P), and calcium (Ca) for larvae of this suite of salamander species taken from Milanovich et al. [59]. We ran statistical analyses in JASP ver. 19.1, a free statistical software that runs on the R Studio platform version 4.1.3 [85].

3. Results

We found 32 sites wallowed by wild pigs. The measured area of wallows ranged from 0.5 to 6.5 m2 with a mean ± 1 standard error of 2.16 ± 0.28 m2. Of the 32 sites, 25 controls had currents whereas only seven were pools. Of the 25 controls with currents, 24 of the matching wallows were pools, although in three cases, a small portion of each wallowing area retained a current. Therefore, the main effect of activity by wild pigs on the habitat was to convert flowing streams with visible current into pools (Figure 2).
Figure 2. Wallowing site (right) comprising multiple wallows made by wild pigs (Sus scrofa) in the Tugaloo River basin of northeastern Georgia, USA. The effect of wallowing was to convert a flowing headwater stream with a visible current into a series of pools. The photo on the (left) shows a portion (control) of the undamaged portion of the same stream. The two photos were taken in early (wallows) and late (control) spring, which accounts for the difference in vegetative growth.
Seventeen of the wallowing sites contained plethodontid larvae, including all three that had some visible current. We collected a total of 76 plethodontid larvae from wallows; the mean number of larvae was 2.34 ± 1.01 with a mean density of 1.35 ± 0.51 m−1. The predominant species were Pseudotriton ruber (red salamander; total n = 28, mean = 0.91 ± 0.69) and Eurycea sp. (total n = 30, mean = 1.47 ± 0.54). We also found egg masses of Ambystoma maculatum (spotted salamander) and Lithobates sylvaticus (wood frog), tadpoles of L. sylvaticus and Anaxyrus americanus (American toad), and a juvenile Lithobates catesbeianus (bullfrog) (Table 2). Four adult Acris crepitans (northern cricket frog) were seen sitting in or traveling through wallowed areas.
Table 2. Amphibian species collected from wild pig (Sus scrofa) wallows and matching control areas in headwater streams in the drainage basin of the Tugaloo River in Stephens County, Georgia, USA. Desmognathus sp. = larvae of D. amphileucus or D. folkertsi; Eurycea sp. = larvae of E. cirrigera or E. wilderae.
We found plethodontid larvae in 26 of the control portions of the streams; of the six that did not have larvae, four were pools. The total number of plethodontid larvae was 178 with a mean of 5.59 ± 0.93 and a mean density of 3.59 ± 0.61 m−1. Species were predominantly P. ruber (total n = 34, mean = 1.06 ± 0.41), Eurycea sp. (total n = 104, mean = 3.56 ± 0.83), and Desmognathus sp. (total n = 19, mean = 0.75 ± 0.23). Other amphibians or amphibian products included egg masses of spotted salamanders and wood frogs in pools as well as four metamorphosed salamanders (Table 2).
Given that numbers of salamanders and species-richness data were integers and the Shannon Index values were not normally distributed (W = 0.8823; p < 0.001), the choice of Wilcoxon signed-ranked tests for analysis was appropriate. More larvae were in the wallows than in the matching controls in only two instances. We found the same number between wallow and matching control only when neither had salamanders. The Wilcoxon signed-rank test indicated a significantly greater number of plethodontid larvae in control portions of streams than in wallows (Z = −3.632; p < 0.001). Concomitant with the difference in salamander number, there was a considerable difference in nutrient standing stocks (Table 3).
Table 3. Estimates of standing stocks in mg m−2 (mean ± 1 standard error) of biomass (dry mass) and major nutrients within larval plethodontid salamanders within headwater streams. Nutrient values per salamander were taken from Milanovich et al. [59].
We found three species of plethodontid larvae in wallows and five species in control portions of streams. In 17 of the 32 sites, there were plethodontid larvae in both wallows and the matching controls. The mean values of the generated Shannon Diversity Indices were 0.183 ± 0.072 for wallows and 0.411 ± 0.078 for matching controls. Because we did not distinguish between the larvae of D. folkertsi and D. amphileucus or between E. cirrigera and E. wilderae, these generated indices likely underestimated actual species diversity. The results of the Wilcoxon signed-rank test indicated that the difference in generated indices was significant (Z = −2.417; p = 0.017). There was also a difference in species richness (Z = −3.640; p < 0.001), with a greater number of species in control sites than in wallows (Table 4). The primary difference in species makeup was the absence of Desmognathus species in wallows.
Table 4. Comparison of wallows and control sites in terms of numbers of species of plethodontid larvae. The list of species is given in Table 2.

4. Discussion

Headwater streams represent an important element of the natural environment that supports sustainability. Making up as much as 75% of river networks [18], they provide critical ecosystem services to downstream communities, including humans. Headwater streams ensure clean water [20] and protect against flooding while aiding in groundwater recharge [21]. In fact, it was the early recognition of the role of headwater streams in controlling downstream flooding that led to the passage of the Weeks Act of 1911 by the U.S. Congress. This landmark legislation enabled the federal government to purchase lands containing headwaters in the eastern U.S. [86] and set them aside as protected areas [87]. In addition, headwater streams are characterized by high levels of biodiversity and endemism [24,25,26,27], contributing to food webs downstream by providing organic matter [22,23] as carbon and other nutrients cycle downstream in a spiraling manner [88].
Critical to the function of headwater streams of the Appalachian Mountains of the eastern U.S. are the roles played by the salamander community. Salamanders replace fish as the dominant vertebrates in headwater systems [57]. Because salamanders occur in high densities in Appalachian headwaters, these organisms are highly productive [54,55]. The larval community in these streams can be relatively complex, consisting of five or more species [89] that interact in various ways, including competition and predation [90]. As mid-trophic-level predators, salamander larvae influence the structure of invertebrate communities [56]. As part of complex food webs, they help regulate energy flow and nutrient cycles [57,58,59,60]. Moreover, salamanders enable nutrient and energy transport between aquatic and terrestrial environments by feeding on allochthonous prey [61] and providing the source pool for adult salamanders that carry out ecological functions in streams, along the stream edge, and out in the riparian forest [91,92]. The biomass of salamanders in headwater streams sequesters considerable amounts of carbon, with estimates of salamanders in Appalachian streams often exceeding 10 g m−2 and with larvae making up the bulk of salamander biomass [57]. The uptake of nutrients by biotic components such as salamanders can shorten a nutrient spiral as these nutrients move downstream, which in turn raises productivity, mitigates downstream eutrophication, and supports biodiversity by giving a greater variety of organisms access to nutrients [88,93]. Salamander larvae further contribute to both biodiversity and nutrient cycling by serving as critical links in the life cycles of parasites [94,95], including within the streams of our study system [96]. Considering the importance of the larval salamander community, damage to this community necessarily impairs the function and sustainability of headwater streams.
We undertook the present study because the effect of wild pigs on aquatic communities, including headwater streams, has rarely been studied [45], although invasive species such as wild pigs have long been considered a threat to native biodiversity [97]. We acknowledge that the effects of pigs as well as the dynamics of salamander populations could possibly vary over time and that we only sampled during one season (spring) of one year. Even so, our data indicate a strong association between activity of wild pigs and both total numbers and diversity of salamanders. Although studies of the effects of wild pigs on aquatic biota are few, our results agree with other investigations that have shown a decline in salamanders [69], fish [98], and aquatic invertebrates [99]. These data also provide at least some support for speculation that wild pigs may have contributed to the decline of several additional salamander species [67,68].
The primary cause of salamander decline that we observed may have been the simple conversion of flowing water to pools, which was true in the vast number of our study streams. Because there were so few instances of control stream sections being pools in our dataset, we did not include flow as a separate variable in our analyses. Therefore, we could not test whether wallowing had an effect over and above that of simple habitat conversion. Even so, simple conversion of current to pool can have profound consequences for the larval salamander community. The reliance on currents by many plethodontid larvae was evident from the absence of any larvae from four of the six control sections without visible currents. In contrast, 24 of the 26 controls with currents had salamanders. Larvae of Appalachian species of Desmognathus, particularly those of D. amphileucus and D. folkertsi, rely almost completely on flowing water [77,100]. The total absence of Desmognathus from pig wallows explains in part the lower species diversity in those habitats. Larvae of E. wilderae also predominately occupy zones of flowing water [82]. Conversely, larvae of Pseudotriton ruber [75,77] and at least one of the Eurycea species (E. cirrigera) frequently occur in pools [82]. While our data indicate a negative impact of wallowing on salamander diversity, we likely underestimated the actual impact on diversity. Our inability to distinguish between the larvae of D. amphileucus and D. folkertsi and between those of E. wilderae and E. cirrigera strengthens the case that wild pigs cause a decline in salamander diversity.
Because salamander communities are also affected by additional environmental variables such as temperature, substrate composition, and dissolved oxygen, we cannot dismiss the possibility that wallowing affected some combination of these variables in a way that contributed to the decline in salamander numbers and diversity we observed. Along with flow rate, further specific testing could reveal the exact nature of the influence that wild pigs have. We also measured surface area rather than stream volume in our pairwise analysis. However, wallows were deeper than the matching control sites, indicating that fewer salamanders in wallows were not the result of less water. Regardless of the specific effect of any of these variables, our data demonstrate a strong association between salamander decline and pig wallowing.
Wild pigs likely have broader effects on the salamander fauna than our data show. For one, the isolated nature and small sizes of headwater streams mean that the amount of habitat available for salamander larvae is necessarily limited, a fact that renders these organisms particularly vulnerable to physical disturbance [26]. Stream reaches characterized by relatively low topographical relief tend to collect salamander larvae as a result of larval drift associated with current [89,101]. Because pig activity is negatively correlated with slope in small streams [69], areas of low relief are targeted by pigs for wallowing, which means that the wallowing does not affect salamanders randomly up and down the stream but differentially impacts areas where larvae are most abundant.
The decline in salamanders we found as a result of pig wallowing likely impacts ecosystem function, including downstream reaches, through its effect on nutrient cycling. In our study, we found that the reduction in salamander numbers in wallows resulted in an estimated 62% decline in standing stocks of major nutrients (Table 3). Such a drop could lengthen nutrient spirals, resulting in nutrients being washed more rapidly downstream rather than being taken up and stored temporarily as salamander tissue. Salamander larvae also significantly impact invertebrate communities [56] and play an important role in nutrient exchange across the terrestrial and aquatic boundary [61]. In addition, fecal contamination by pigs, whether wild or domestic, results in increased concentrations of nutrients, suspended solids, and fecal coliform bacteria [43,102], possibly impacting pH and levels of dissolved oxygen. The effects of these changes are not restricted to wallowing sites but are easily spread downstream. The presence of a healthy larval salamander community might help mitigate these effects by absorbing nutrients into the complex food web to which salamanders belong.
In addition, the role of salamander parasites on biodiversity and nutrient transfer is often overlooked [103]. For example, D. amphileucus and E. wilderae larvae act as important links in the complex life cycle of the trematode parasite Metagonimoides oregonensis [94,95], including in our study streams [96]. These salamanders serve as second intermediate hosts with high rates of infection and thereby provide a conduit for the free-swimming trematode larvae (cercariae) to eventually reach the definitive host, which is raccoons (Procyon lotor) or minks (Neogale vison) [94]. Because cercariae represent considerable sources of organic carbon in aquatic systems [103], the decline or loss of these salamander species represents an additional potential consequence for nutrient cycling in headwaters.
While there is a large body of literature on the effects of wild pigs on biodiversity and other focal points for sustainability, e.g., [37,38,39,40,41,42,43,44,45,104], a number of questions remain to be investigated regarding the full effects of their activities. For example, what is their effect on carbon cycling and sequestration, which have implications for climate change (e.g., [36])? How does the decrease in salamander number and diversity affect the overall food web of the streams and adjoining riparian zones? How do changes to the headstream food web affect energy flow, nutrient cycling, and carbon sequestration (e.g., [105]), particularly downstream? Does the complexity that salamanders contribute to the food web help mitigate the effects that wild pigs have on water quality by absorbing and storing nutrients?
By decreasing salamander number and diversity, wild pigs likely impair a critical functional group in Appalachian headwater streams. Because of the importance of these systems to the health of entire stream networks and the societies that depend upon them, the removal of wild pigs, though difficult [106,107,108], is necessary to fully support all three pillars of sustainability.

5. Conclusions

Headwater streams are critical suppliers of valuable ecosystem services to downstream consumers, thereby supporting the environmental pillar of sustainability. An important functional group in Appalachian headwater streams is the community of larval plethodontid salamanders, which serve as mid-trophic-level predators. Their roles in complex food webs and organic production enable carbon sequestration as well as nutrient cycling and energy flow within the stream and between the stream and the surrounding riparian forest.
We show that wild pigs, a notorious invasive species, negatively affect both numbers and diversity of salamanders in Appalachian headwater streams. Our results provide yet another reason for programs to control and eliminate this invasive species because of its detrimental impacts on natural habitats and biodiversity. However, many questions remain unanswered. In particular, there is need for further study on the effects of the impairment of this functional group, specifically on consequences for nutrient cycling and non-salamander biodiversity (e.g., parasites), because of the importance of these systems to sustaining native biodiversity and a healthy overall landscape.

Author Contributions

Conceptualization, C.D.C.; methodology, C.D.C. and E.M.; software, C.D.C.; validation, C.D.C. and E.M.; formal analysis, C.D.C.; investigation, C.D.C. and E.M.; resources, C.D.C.; data curation, C.D.C.; writing—original draft preparation, C.D.C.; writing—review and editing, E.M.; visualization, C.D.C.; supervision, C.D.C.; project administration, C.D.C. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

This study is waived for ethical review as Piedmont University is primarily a teaching institution and thus not required to have a formal review board for animal re-search by the School of Arts and Sciences and the Department of Natural Sciences.

Data Availability Statement

The raw data supporting the conclusions of this article will be made available by the authors on request.

Acknowledgments

This study was completed under the auspices of the Piedmont University Natural Sciences Honors Program. We thank the Georgia Department of Natural Resources and the US Forest Service for issuing permits.

Conflicts of Interest

The authors declare no conflicts of interest.

Abbreviations

The following abbreviations are used in this manuscript:
USAUnited States of America
USUnited States

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