Gopher tortoises (Gopherus polyphemus), the only land tortoises native to the southeastern United States, are found throughout their range (from southern South Carolina to eastern Louisiana) in a variety of upland habitat types including sandhills, pine flatwoods, and xeric hammock, as well as in coastal habitats such as beach dunes (Diemer 1986). Throughout the southeastern United States, gopher tortoise activities and burrow use by commensals in upland pine-dominated habitats have received much attention (e.g., Ott et al. 2000; Boglioli et al. 2003; Eubanks et al. 2003; Catano and Stout 2015; Knapp et al. 2018; Epperson et al. 2021; Goessling et al. 2021; Murphy et al. 2021), but fewer studies have examined their use of coastal beach dune habitats (e.g., Smith et al. 2005; Lau and Dodd 2015; Blonder et al. 2021). It is important that we study beach dune communities, in particular, because some of the highest gopher tortoise burrow densities have been observed in this vulnerable, yet critical, habitat (Kushlan and Mazzotti 1984; Pawelek and Kimball 2014). Considered a threatened species throughout most of its range, gopher tortoise populations have decreased by an estimated 80% over the last 100 yr (Auffenberg and Franz 1982). Their decline can be attributed to a number of factors, including habitat fragmentation and alteration, harvest by humans, disease, road mortality, and sea level rise (Diemer 1986; McCoy et al. 2006; BenDor et al. 2009; Blonder et al. 2021), with coastal beach dune habitats being some of the most heavily impacted by human activity and a changing climate (e.g., Blonder et al. 2021). Gopher tortoise populations are predicted to continue to decline, especially without increased conservation and management (Folt et al. 2022).

Gopher tortoises construct burrows for protection from adverse weather, extreme temperatures, and predators. They prefer open sandy areas to dig their extensive burrows, which typically range between 3 and 6 m in length with average depths around 2 m at a ∼30° angle (Hallinan 1923; Doonan and Stout 1994). Gopher tortoises spend a large portion of their time in and around their burrows, with many activities such as foraging and mating occurring within ∼20–30 m of their burrow (Lau and Dodd 2015; Castellón et al. 2018). Individual gopher tortoises often dig not just 1 but several burrows to use for thermoregulation, rest, and nest sites (Smith et al. 2005), and because tortoises spend considerable time at burrows, these places are also typically where competitive intrasexual relations and mating activities occur (Radzio et al. 2017). Though gopher tortoise burrows are thought to host a variety of tortoise behaviors, it can be difficult to document these behaviors in the field because of the tendency of individuals to retreat into burrows when approached (Radzio et al. 2017). In addition to gopher tortoises, hundreds of other animal species (i.e., commensal species) are dependent on these burrows for shelter and food, leading gopher tortoises to be considered a keystone species in these habitats (Catano and Stout 2015). Thus, in effect, gopher tortoise burrows act as a shared habitat resource among gopher tortoises and these numerous commensal species. Observing animal behavior at gopher tortoise burrows without disturbing the habitat or animals is critical, and commonly used sampling techniques such as animal traps, burrow excavation, or in-person visual surveys may influence animal behavior (e.g., traps may selectively catch some animals and deter others), damage or destroy the burrow habitat (e.g., the burrow may permanently lost), or limit data-gathering opportunities (e.g., ability to sample only when people are available and capable). However, to ameliorate these potential limitations, studies have turned to the use of nonintrusive motion-activated wildlife cameras to continuously capture animal activity at gopher tortoise burrows with much success (Alexy et al. 2003; Dziadzio and Smith 2016; Dziadzio et al. 2016; White and Tuberville 2017; Murphy et al. 2021).

In this study we sought to examine the seasonal and diel behavior patterns of gopher tortoises and commensal species at gopher tortoise burrows in coastal beach dune habitat. Using motion-activated wildlife cameras, gopher tortoise burrows were monitored over a 12-mo period in an undeveloped section of coastline located in St. Augustine, Florida. Through examination of gopher tortoise and commensal species behavioral patterns, this study will allow for a better understanding of how these animals use burrows as a shared habitat resource, as well as the larger ecological role that gopher tortoises and their burrows play in coastal beach dune habitats.

METHODS

Study Site. —

The study was conducted in an area of undeveloped beach dunes along the northeast Florida Atlantic coast that is part of the Guana Tolomato Matanzas National Estuarine Research Reserve (hereafter referred to as the GTM NERR) located in St. Augustine, Florida. Located on the east side of highway A1A within the reserve, this undeveloped beach dune habitat extends north-south along the coast for approximately 6.5 km (100 m at its widest point east-west) and includes approximately 47 ha of vegetated coastal habitat (beach dune and coastal strand). The dunes are some of the highest in the state, ranging up to 12 m high, and are bordered to the north and south by private residences (Blonder et al. 2021). Most of this dune habitat is at a high enough elevation farther up the beach face that it is protected from the impacts of extreme weather events such as hurricanes that cause higher than normal water levels and can lead to erosion (Blonder et al. 2021). Within this undeveloped beach dune habitat, a 26-ha area is accessible for surveying gopher tortoise burrows and is roughly divided into 2 equal beach sections, termed the northern and southern sections, by an emergency access road through the dunes. The primary vegetation consists of sea oats (Uniola paniculata), saltmeadow cordgrass (Spartina patens), blanketflower (Gaillardia pulchella), camphorweed (Heterotheca subaxillaris), railroad vine (Ipomea pes-caprae), and spotted beebalm (Monarda punctata) (Frazel 2009; FNAI 2010; Pawelek and Kimball 2014).

A survey of gopher tortoise burrow density was conducted in 2011 (Pawelek and Kimball 2014), and a subset of these burrows (n = 10) located in the dunes were selected for observation with wildlife cameras (Supplemental Fig. 1; all supplemental material is available at http://dx.doi.org/10.2744/CCB-1600.1.s1). Burrows (n = 10 total) were monitored in both the northern and southern components of the undeveloped beach (n = 5 burrows in each component; Supplemental Table 1). Two adult burrows, 1 north and 1 south of the emergency access, were monitored year-round with motion-activated wildlife cameras beginning March 2012 and ending March 2013. Four adult burrows each were monitored with cameras in the north and south quarterly, for 6-wk blocks during each sampling period. Because of burrow collapses during the study period, some burrows were dropped or added, leading to varying coverage for some burrows (Supplemental Table 1).

Tortoise Burrow Monitoring. —

From March 2012 through March 2013, motion-activated wildlife cameras (Bushnell Trophy Cam with 16 gigabyte SD cards) were set up at these 10 burrows within the coastal dunes. Each burrow was monitored using 2 cameras: 1 camera facing the burrow entrance from directly in front, and the other camera from the side. Predeployment trials determined that the use of 2 cameras at each burrow would provide the greatest amount of information on burrow visitation because using the 2 different angles allowed for a more complete view of the burrow and area around the entrance. Cameras were mounted on a wooden stake and placed at least 1.5 m from the burrow entrance and at least 1 m off the ground. Cameras were set to record video for 30 sec for each motion-activated detection event as a video period of 30 sec was determined during predeployment trials to provide sufficient information on animal activity at burrows, while maximizing storage capacity on camera memory cards (all cameras and burrows were inspected in the field at least every 15–30 d). Videos allowed us to interpret behaviors of both gopher tortoises and their burrow commensals, which can sometimes be challenging with photos only (e.g., White and Tuberville 2017).

Video Processing and Data Analyses. —

All video recordings were viewed to detect and observe the behaviors of gopher tortoises and their commensals at monitored gopher tortoise burrows. The lead author completed all video review to avoid viewership bias, and all authors contributed to species identifications. For each video file, the file name was recorded, as well as the date and time, burrow number, camera number, if a gopher tortoise was seen (Y/N), if another animal was seen (Y/N), if an organism was seen inside the burrow (Y/N), if an organism was seen outside the burrow (Y/N), taxon observed, and a detailed description of activity, which additionally included species identification information and numbers of individuals present. If a gopher tortoise had been observed at a burrow within the past 7 d, the burrow was classified as active. We had no cameras inside the burrow itself, thus “inside” refers to the burrow tunnel that was able to be seen, and “outside” refers to the burrow apron and the burrow’s visible surrounding dune environment. Inside and outside were not mutually exclusive when recording data regarding a video file, and therefore if a tortoise or other animal was both inside and outside the burrow in the 30-sec clip, a “Y” was recorded for both inside and outside.

Gopher tortoise behavior was categorized as one of the following 5 behaviors (Fig. 1): aggressive, burrow maintenance, foraging, mating, and resting based on behavior categories used in previous studies (Mushinsky et al. 2006; Dziadzio and Smith 2016; Radzio et al. 2017). Aggressive behavior included ramming, flipping, and burrow blocking behaviors. Burrow maintenance behavior included a variety of manicuring and earth-moving behaviors (ground nuzzling, roughing up and kicking the sand, intensive digging, and sand compacting). Foraging behavior included eating or carrying away plant material. Mating behavior included head bobbing and mounting attempts. Resting behavior included basking outside the burrow and motionless periods inside the burrow tunnel. Rough female-male interactions were not classified as aggressive behavior because it is very difficult to distinguish subtle aggression from mating activity (e.g., Radzio et al. 2017). Similarly, manicuring and earth-moving behaviors at the burrow were combined under burrow maintenance to avoid assumptions, considering that it can be difficult to distinguish between a tortoise engaging in an activity such as clearing sand to make a path to the burrow and clearing sand to prepare a nest.

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Commensals observed at gopher tortoise burrows were identified to the lowest taxonomic level possible using available literature and identification guides. Because we could not distinguish between some rabbit species on videos, all Sylvilagus observations were combined under Sylvilagus spp. Possible species for this genus that occur in the southeastern United States include the eastern cottontail (Sylvilagus floridanus) and the marsh rabbit (Sylvilagus palustris). This was similarly done for grasshoppers of the genus Schistocerca (Capinera et al. 2001). Possible species for this genus that occur in the state of Florida include the spotted bird grasshopper (Schistocerca alutacea), the American bird grasshopper (Schistocerca americana), the mischievous bird grasshopper (Schistocerca damnifica), and the rusty bird grasshopper (Schistocerca rubignosa). Commensal taxa that were observed in more than 40 separate camera days were analyzed for diel and seasonal patterns. Differences in commensal burrow use between active and inactive burrows were examined using a chi-square test between the number of days a taxa was observed in an active or inactive burrow.

Videos from the same burrow but different camera positions (front and side views) were reduced to 1 sighting to avoid duplicate records. Similarly, to reduce the potential for overestimating burrow use by the same individual, videos that occurred within 60 sec of one another were also reduced to 1 sighting, and presence/days observed was used whenever possible in analyses to minimize bias due to duration of time an individual spent at the burrow (e.g., Dziadzio and Smith 2016; Murphy et al. 2021). We calculated observation days as the sum of all burrows being observed on each individual day within each month. Average observation percentage was then calculated by dividing the sum of all days within a month that a behavior or taxon was observed by the observation days (i.e., sampling effort) for that month. Definitions for day and night in this study were modeled after those from Dziadzio and Smith (2016), with “day” spanning 0630–2029 hrs and “night” 2030–0629 hrs.

Because the activity patterns of gopher tortoises and commensal species may be impacted by air temperatures and seasonal changes (Lips 1991; Alexy et al. 2003; Harris et al. 2015; Castellón et al. 2018), we examined animal activity patterns against air temperatures in the area during the study period. Within the GTM NERR, air temperature was measured every 15 min at the Pellicer Creek meteorological station maintained as part of the System-Wide Monitoring Program at the reserve (downloaded from the NERR Centralized Data Management Office on 18 November 2022; https://cdmo.baruch.sc.edu/). Average hourly air temperature from this site was obtained by averaging values from the four 15-min increments. To compare the effects of air temperature on different tortoise behaviors, we regressed the probability of observing each behavior (as a percent of all hourly observations that camera traps were recording) against the air temperature measured during each hourly observation. We then fit an exponential growth curve (y = ae^bx) to each behavior’s data and calculated the R² and p-value for the fit of the exponential regression.

RESULTS

Camera traps were actively recording for a total of 2179 d across 10 different burrows. Monitoring intensity varied somewhat between burrows (Supplemental Table 1), as some were monitored for single, short periods (burrows 18 and 38 for 37 d each), others for a full continuous year (burrows 23 and 216), and some periodically throughout the study year (varying from 143 to 335 d). These observations resulted in a total of 39,248 video files where the camera traps were active, with animals present in 21% of the recorded video files. Gopher tortoises were detected in 843 of the total observation days, and commensals were detected in 619 of the total observation days.

Gopher Tortoise Burrow Use and Behavior. —

From March 2012 to March 2013, gopher tortoises were observed year-round, with the highest observation percentage in May (63%) and lowest in December (16%) (Fig. 2). In terms of diel activity patterns, gopher tortoises were detected on cameras from 0100 to 2000 hrs with the highest number of sightings in the morning (around 9 AM) and lowest predawn (1 to 4 AM) (Fig. 3). Gopher tortoises displayed all 5 types of behavior year-round (example images of these types of behavior are shown in Fig. 1), but these behaviors were mostly observed during the spring months. The month with the highest mean presence of aggressive behavior was April, for burrow maintenance it was a near tie between April and May, for foraging it was April, for mating it was April, and for resting behavior it was a tie between April and May (Fig. 2). Burrow maintenance, foraging, and resting behavior had a higher mean occurrence in warmer months than in the winter months overall.

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Although gopher tortoises were observed during both the day and night, most behaviors were displayed during the daytime (Mann-Whitney rank sum test, p < 0.001; Fig. 3), and 99% of tortoise observations occurred between 0630 and 2029 hrs. Gopher tortoises were observed displaying aggressive behavior between 0700 and 1700 hrs, burrow maintenance behavior between 0600 and 1800 hrs, foraging behavior between 0600 and 1700 hrs, mating behavior between 0600 and 1700 hrs, and resting behavior between 0500 and 2000 hrs. Peak total sightings for most behaviors were in the morning, except for aggressive behavior, which peaked in early afternoon. Resting was the most frequently recorded behavior. Gopher tortoises were more active overall at higher temperatures, and all 5 gopher tortoise behaviors showed a positive exponential relationship between mean occurrence of the behavior and hourly mean air temperature (Fig. 4).

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Commensal Species Burrow Use. —

A total of 51 taxa other than gopher tortoises were observed using tortoise burrows and their aprons, 29 of which were identified to species (Table 1; Supplemental Fig. 2). The number of taxa observed varied by season with the highest number in fall (n = 33), lowest in winter (n = 20), and spring (n = 26), and summer (n = 31) between these. Most taxa were observed at gopher tortoise burrows during the day (n = 47) rather than at night (n = 21), although some taxa (n = 17) were observed during both day and night. The class Mammalia (n = 13) notably contained many taxa that were seen year-round or at least once a season. Classes Reptilia (n = 10) and Amphibia (n = 2) were observed in spring through early fall, with most species being seen solely during these seasons. Though some class Aves species (n = 10), such as mourning doves (Zenaida macroura), had sightings year-round, birds in the order Passeriformes (n = 7) were seen primarily in the fall and winter. The class Insecta (n = 16) was highly variable between taxa; the order Lepidoptera (n = 7), however, had a strong preference for the spring through fall. Many commensal species had sightings inside burrows including the eastern coachwhip snake (Masticophis flagellum flagellum), Florida crowned snake (Tantilla relicta), Carolina wren (Thryothorus ludovicianus), domestic dog (Canis lupus familiaris), bobcat (Lynx rufus), raccoon (Procyon lotor), nine-banded armadillo (Dasypus novemcinctus), Virginia opossum (Didelphis virginiana), oldfield mouse (Peromyscus polionotus), and Norway rat (Rattus norvegicus), among others (Table 1).

Table 1. List of animal taxa observed by motion-activated wildlife cameras at coastal dune gopher tortoise burrows over the 12-mo study period (March 2012–March 2013). Total camera days observed is a sum of all days when that taxon was observed in each burrow (out of 2179 potential observation days). Taxa previously undocumented in association with gopher tortoise burrows are marked with an asterisk (*).

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The most sighted species exhibited clear seasonal patterns in their use of gopher tortoise burrows in beach dunes (Fig. 5). Diel burrow use patterns varied by species with some of the most sighted species exhibiting largely diurnal behavior periods (Fig. 6). No significant difference was found (chi-square test, p > 0.05) between the probability of observing any taxon in an active or inactive burrow.

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DISCUSSION

Gopher tortoises used burrows in coastal dune habitats year-round, with the most activity observed during summer months, and they were predominantly diurnally active, which is consistent with other studies (McRae et al. 1981; Alexy et al. 2003; Radzio et al. 2017). Observations were generally highest in the mornings (0800–1200 hrs) and we observed very few tortoises during the late afternoon (after 1600 hrs), indicating that gopher tortoises using these dune burrows likely focus their activities on the morning and midday hours, returning to their burrows well before dark. Resting, foraging, burrow maintenance, and aggressive behaviors all showed similar diel patterns, with peak activity occurring from 0700 to 1400 hrs. In contrast with the other observed behaviors, mating showed a bimodal distribution in diel activity, with peaks occurring around 0900 and 1300 hrs. The dip in mating activity was centered around 1100 hrs, which coincided with peak foraging activity. This suggests mating may take place before and after foraging, with foraging taking precedence during the middle of their active period. Alternatively, tortoises may be avoiding strenuous activity during the hottest parts of the day in the summer (Alexy et al. 2003), a pattern previously observed in feeding foray frequency during July and August (McRae et al. 1981).

Tortoises were most frequently observed during the spring and summer months (April–August), with the fewest observations occurring in the winter (December–February). This is consistent with seasonal tortoise movement patterns observed in pine-wiregrass habitat in Georgia (Eubanks et al. 2003) and in mesic flatwoods and scrub habitats in Florida (Castellón et al. 2018). Burrow maintenance, mating, foraging, and resting all showed similar seasonal patterns as the overall observations, with higher observations April through August, and lowest activity December through February. Previous studies in longleaf pine (Pinus palustris) forests in northern Florida and southern Georgia documented peaks in mating and nesting during May, June, and July (Iverson 1980; Landers et al. 1980; Mushinsky et al. 2006; Radzio et al. 2017). Our observations of burrow maintenance and mating in coastal beach dune habitat were generally consistent with these previous studies, but we did see slightly earlier seasonality, with April having the highest number of observations of those behaviors as well as aggressive interactions.

Warmer winter temperatures in northeast Florida coastal beach dunes, compared to previous studies of inland Georgia and Florida habitats, may explain the activity we observed and the earlier seasonal start of aggressive, burrow maintenance, and mating behaviors. All 5 of our observed behaviors showed positive, exponential relationships with mean hourly air temperature. McRae et al. (1981) observed a similar increase in feeding activity along with temperature from 22°C to 31°C, but then observed a decrease in activity at temperatures above 31°C, although they acknowledge a small sample size. Our observations of burrow maintenance, foraging, and resting in beach dune habitat all displayed an increase in occurrence up to the maximum measured air temperature of 34°C, but both mating and aggressive behaviors had a decrease from 33°C to 34°C, which may also be due to a smaller sample size at higher temperatures. Although we collected only 1 yr of data, these results suggest tortoises in these coastal beach dune habitats may begin breeding earlier than their inland counterparts, perhaps because of milder winter temperatures. In addition, previous studies have observed minimal winter activity by gopher tortoises, often limited to periods when air temperatures are above 18°C–21°C (McRae et al. 1981; Diemer 1992), but we observed some resting, foraging, and burrow maintenance activity at temperatures lower than this.

Coastal dune gopher tortoise burrows support a large and diverse assemblage of commensal species. In this study, 51 animal taxa besides gopher tortoises were observed using tortoise burrows and their aprons in coastal beach dunes, 29 of which were identified to species. These commensal species included a variety of vertebrate (classes Reptilia, Amphibia, Aves, and Mammalia) and invertebrate (classes Insecta and Arachnida) species. The majority of the vertebrate taxa have previously been documented in association with or utilizing gopher tortoise burrows, and the observed commensal community in the coastal dunes was similar to those in other habitats in Florida (Hallinan 1923; Young and Goff 1939; Jackson and Milstrey 1989; Lips 1991; Witz et al. 1991; Kent and Snell 1994; Kent et al. 1997; Alexy et al. 2003; Catano and Stout 2015; White and Tuberville 2017; De Souza 2018; Martinet 2018; Hipps 2019; Whitfield et al. 2022), Georgia (Dziadzio and Smith 2016; Dziadzio et al. 2016; Knapp et al. 2018; Lamb 2021; Murphy et al. 2021), and Mississippi (Epperson et al. 2021). It is of note that, like many coastal dunes, our study area was closely bounded by a major highway, which may have restricted access to burrows by some commensals, especially in comparison to inland sites less impacted by local human infrastructure. However, 2 bird species previously unreported in association with burrows, bobolink (Dolichonyx oryzivorus) and northern waterthrush (Parkesia noveboracensis), were detected by our camera traps. In contrast, all the observed invertebrates identified to genus or species (8 in total) were previously undocumented in association with gopher tortoise burrows, although invertebrate commensal communities have not been as well investigated as vertebrate commensals. While many of these previously undocumented taxa were observed multiple times at the burrow aprons, none were observed entering the burrows. Without further investigation, it is difficult to say if these taxa are drawn to the burrows themselves or are simply transients through the area.

In general, classes Reptilia and Amphibia were seen during the spring months through early fall, with most species being seen solely during these seasons. This is likely because of ectotherm temperature demands and brumation/hibernation during winter months. Though some bird species, such as mourning doves, had sightings year-round, birds in the order Passeriformes were seen primarily in the fall and winter. This may be the result of southward migration through Florida by several species in the colder months. The class Insecta was somewhat variable between species, but generally the orders Lepidoptera and Orthoptera were most commonly seen spring through fall. Grasshoppers notably had a large increase in observations during September and October. Of the Mammalia species, several showed distinct seasonality. Raccoons were mostly seen in the late fall and winter, which could indicate that burrows are primarily used by raccoons as shelter from low temperatures. Rabbits (Sylvilagus spp.) were more commonly observed in late winter and spring, which coincides with their peak reproductive season (Holler and Conaway 1979). Bobcats lacked a strong seasonality and were seen fairly evenly throughout the year.

There was considerable overlap in the seasonal and diel use of gopher tortoise burrows in coastal dune habitats by gopher tortoises and commensal species. With the large number of commensal species observed throughout the year and the near year-round burrow use by some of the most abundant commensal species (especially bobcats and mourning doves, with some months absent for grasshoppers, rabbits, and raccoons), the degree of burrow use overlap with gopher tortoises (year-round users) is not surprising. Gopher tortoise activity at these dune burrows was wholly diurnal, and 2 of the most abundant commensal species, grasshoppers and mourning doves, followed the same activity pattern. More nocturnally active commensal species were observed visiting burrows during both day and night (e.g., rabbits and bobcats) or only during nighttime hours (raccoons). In coastal strand habitat in central Florida, commensal species activity was highest at night (Pike and Grosse 2006). Interactions between gopher tortoises and commensal species have been observed (e.g., a fox and a tortoise; Radzio et al. 2017), but we rarely saw these interactions in the footage captured for this study. In addition, the frequency of commensal species use of burrows can differ depending on if the burrow was active (had a resident gopher tortoise) or inactive (no tortoise present or evidence of tortoise burrow use). Increased visitation to active burrows was observed for all vertebrate commensal taxa, including raccoons, rabbits, and mourning doves in longleaf pine habitat in Georgia (Dziadzio and Smith 2016). The presence of tortoise scat may attract coprophagous insects, which leads to increased resources for higher trophic levels as well (Dziadzio and Smith 2016). In contrast, reptiles were found more commonly in active burrows, but no other commensals showed a preference for active versus inactive burrows in upland sandhill habitat in west-central Florida (Witz et al. 1991). In xeric oak and pine habitat in central Florida, no differences in commensal use were observed between active and inactive burrows (Kent and Snell 1991). We found no difference in use between active and inactive burrows in coastal dune habitat for our 5 most abundant commensal species (grasshoppers, rabbits, bobcat, raccoon, and mourning dove). Tortoise presence could have an impact on the attractiveness of a burrow to potential commensal taxa because active burrows may be better maintained and provide higher quality shelter than nonactive ones (Lips 1991). Taxa that tortoises view as a threat or competitor may be defended against by the tortoise, but nonthreatening species may receive protection from their own predators by associating with tortoises. Additionally, potential predators of tortoises or their eggs (e.g., coyotes, dogs, raccoons, rats, opossums) may be drawn to active burrows.

The observation of these overlapping seasonal and diel coastal dune burrow habitat use patterns by gopher tortoises and commensal species demonstrates the shared nature of the burrow habitat as a resource for these species and highlights the keystone effects of gopher tortoises in these ecosystems (Catano and Stout 2015). Nevertheless, observing these temporally overlapping behaviors for extended periods of time (e.g., 24 hrs a day for weeks or more) is possible only with sampling gears such as motion-activated wildlife cameras that can make passive, nonintrusive observations that don’t disturb natural activity patterns and ecological interactions, as opposed to, for example, species-specific traps that might attract 1 species and deter or limit others at the same time. Since motion-activated wildlife cameras permit observation of these behaviors by both gopher tortoises and commensal species, we were able to document fine-scale shared habitat use among these animals, which provides an interesting layer of context that is not possible when each group is examined independently. However, it is important to note that small animals and cryptic visitors to the burrows may not have triggered the cameras as easily as bigger animals, and therefore may have been underrepresented in our observations. Further, with the cameras focused on the burrow entrance area, it was not possible to observe behaviors that occurred deep within the burrow or those that might have occurred farther away from the burrow entrance.

This study provides information on the behavior of gopher tortoises and use of their burrows in lesser studied tortoise habitat: coastal beach dunes. Seasonal patterns of gopher tortoise behavior showed earlier initiation than those of inland populations. Diel patterns of tortoise behavior were principally diurnal, with a large drop-off in activity in the late afternoon and evening. Commensal communities were similar to those in inland habitats, but 2 new bird species and 8 new invertebrate taxa were observed in association with tortoise burrows. Coastal dunes are distinct habitats and are highly threatened by anthropogenic impacts, thus, our study provides important information on gopher tortoise behavior and commensal communities that are distinct from inland ecosystems.