An Ethogram Describing the Nesting Behavior of Green Sea Turtles (Chelonia mydas)

For animals that do not defend or provision their offspring, the behavioral components of parental care are limited to nesting behaviors. These behaviors are typically associated with site choice, site preparation, concealment of eggs, and insulating eggs from adverse environmental conditions (Hughes and Brooks 2006; Royle et al. 2012). Across sea turtles, nesting behaviors of emergence onto land, digging an egg chamber, oviposition, and covering the eggs are remarkably conserved, with variations on common themes (Hailman and Elowson 1992; Miller and Dinkelacker 2008). These behaviors result in sea turtle eggs being buried within beach sand.

General examinations of the nesting process have focused on describing distinct nesting stages and durations (Hendrickson 1958; Carr and Ogren 1960; Bustard 1972; Miller 1997). Ethograms allow a more detailed examination of sea turtle nesting behaviors by identifying distinct modal action patterns (Miller 1997). Modal action patterns are a fundamental element of ethological descriptions and are composed of an individually defined series of movements (Tinbergen 1963; Lorenz 1971). As such, these movements are expected to run to completion somewhat independent of sensory inputs (Cassidy 1979).

Although ethograms have been developed for other turtle species (Liu et al. 2009; Smart et al. 2014), most authors examining sea turtle nesting behavior have instead focused on factors influencing nest-site selection, such as nest microclimate (Ackerman 1997), location relative to the sea (Pike and Stiner 2007), substrate (Mortimer 1990), and obstacles (Witherington et al. 2011), with hypothesized links to egg and hatchling survival. Hailman and Elowson (1992) provided the most complete ethogram for sea turtle nesting, which focused on the behaviors of Loggerhead Sea Turtles (Caretta caretta). Their investigation identified 50 distinct action patterns composing 10 nesting phases. Although they did not produce an ethogram, Nishizawa et al. (2013) examined sea turtle action patterns using accelerometers to measure periods of activity within the nesting stages of Green Sea Turtles (Chelonia mydas) precisely. We found no ethogram in the literature describing the nesting behavior of Green Sea Turtles.

A thorough description of nesting behaviors has important applications for sea turtle conservation. Ethograms can be used to measure changes to typical nesting behavior from an assortment of potential threats including direct human encounters, interactions with coastal armoring structures, and artificial lighting, all of which could impact both the nesting process and nesting success. Using ethograms, a greater understanding of these impacts on nesting females could better inform coastal management decisions.

In developing an ethogram for the nesting stages of Green Sea Turtles, we combined in-person data collection with night-vision video-recording of nesting Green Sea Turtles. We subsequently coded the video-recorded footage for specific nesting behaviors and action patterns. We intended for these methods to add new detail to previous descriptions of the nesting behaviors of Green Sea Turtles and to inform management and regulatory agencies as they assess both biotic and abiotic disturbances to sea turtles while they nest.

We studied Green Sea Turtles nesting in the Archie Carr National Wildlife Refuge in Brevard County and near Disney's Vero Beach Resort in Indian River County, Florida, USA, between June and August 2014–2015. Both beaches are narrow, as is characteristic of southeastern Florida, and include natural and artificial dunes. During the study period, nesting by Green Sea Turtles ranged from approximately 70–600 nests/km/yr.

We encountered subjects by patrolling the beach at night using Night Optics monocular passive night vision goggles and no aid from external light sources. All observations of Green Sea Turtles were made between 2100 and 0600 h local time. Once a turtle was encountered, a team of two observers recorded in-person behavioral observations for each subsequent nesting stage, including the start time (hh: mm: ss) of each stage, based on predefined behavioral signals that were recognizable from the shoreline (Hailman and Elowson 1992; Witherington and Witherington 2015). To minimize disturbance, observers waited until the turtles had moved landward of the recent high-tide mark before crawling up the track behind the turtle, taking care not to be in the turtle's line of sight throughout the nesting process.

During the 2015 nesting season, we video-recorded nesting behaviors of Green Sea Turtles to supplement the data collected in person. We recorded video footage using a Sony HDV NightShot camcorder with six infrared LED illuminators attached to a 4-m pole. The pole allowed observers to video-record the turtle from above in order to view all head and flipper movements. Because we were unable to use the camera's viewfinder while it was mounted atop the pole, we centered the turtle in the camera frame with the use of a deep-red (650 nm) laser diode (laser pointer) as an aiming device. We used a light with deep-red coloration because red light is minimally visible to sea turtles (Witherington et al. 2014). To ensure that the observer did not miss any data points, one observer operated the video-recording apparatus while the other collected the in-person data.

We collected in-person data for a total of 14 Green Sea Turtles, 3 in 2014 and 11 in 2015. Of the 11 Green Sea Turtles we observed in 2015, we video-recorded 8 using the Sony camcorder. The time amounted to a total of 18.75 h of video-recorded footage.

Two of us (RL, EN) coded the video-recorded footage into quantitative measurements using flipper-stroke counts. One author (RL or EN) recorded the number of rear flipper strokes while the other recorded the number of front flipper strokes. We viewed the video-recorded footage 3× slower to increase precision in the coding process (∼57 h of coding time for the eight subjects). We recorded the start and stop times for each active period, defined as a series of consecutive flipper strokes, and for each latency period, defined as the duration between the end of one active period and the start of the next active period. We also recorded the total number of flipper strokes and head/gular movements within each active and latency period. Initially, we coded seven types of flipper movements based on which flippers were in motion and whether the strokes were simultaneous, paired, alternating, or single (Fig. 1). We defined simultaneous strokes as movements in which all four flippers were used concurrently (Fig. 1a). Paired strokes we defined as two flippers moving concurrently (Fig. 1b) and alternating strokes we defined as asynchronous movement of the right flipper followed by the left flipper or vice versa (Fig. 1c). Lastly, we defined single strokes as flipper movements made independent of other flipper actions (Fig. 1d–g). We also counted the number of head raises, lateral head movements, and gular movements within each period of activity and latency. The coding authors alternated between coding front flipper and rear flipper observations to minimize observer bias. When only one coding author was available, that individual watched the video footage with one anatomical focus (e.g., front flippers), then watched the video footage again with a different focus until front flipper strokes, rear flipper strokes, and head/gular movements were all counted. After coding the video footage, we further delineated nesting stages into distinct action patterns to describe the observed flipper, head, and gular movements.

We divided observed behaviors into seven nesting stages, similar to the stages described by Hailman and Elowson (1992) for Loggerhead Sea Turtles. Within each stage, we calculated stroke rate as stroke count per min for head and flipper movements. We then examined changes in stroke rate over the course of each nesting stage. We observed latency periods during all nesting stages and included those periods of inactivity in the total nesting time for each turtle. We did not include the six turtles that were not video-recorded in the stroke rate analysis. We compared nesting stage durations using the in-person data collection method and the video-recording method, and determined that the two methods yielded similar results (Wilcoxon signed rank test, Z = –0.87, P = 0.39), so we included all 14 observed turtles in our analyses of total nesting stage durations.

During review of the video-recorded data, we observed seven distinct nesting stages: ascent, body pitting, digging, egg laying, covering, camouflaging, and descent (Fig. 2). Total nesting duration for the encountered turtles ranged from 99–213 min (Table 1).

We identified six predominant flipper action patterns during the nesting process. Flipper action patterns related to a unique series of movements, which we observed in either left or right flippers, rear or front flippers, and moved in a single, paired, or alternating pattern. Additionally, we observed paired flipper strokes in the front flippers only, and alternating flipper strokes in the rear flippers. The frequency of each action pattern occurring within a nesting stage (Table 2), and the length of activity and latency periods for each action pattern (Table 3), all varied throughout the nesting time line. Other than flipper movements, we noted three additional action patterns during latency periods: head elevation–depression (HED), head lateral turn (HLT), and gular expansion (GEX). Whereas Hailman and Elowson (1992) identified each individual movement as a separate action pattern, we present our action patterns as a sequence of distinct movements.

While coding the video-recorded footage, we observed an action pattern between body pitting and digging not found in other nesting stages. Because this action pattern is temporally unique, we labeled the period during which it was used as the body pitting to digging transition (henceforth referred to as the Transition Period).

In describing the distinct nesting stages, as well as the Transition Period, we included other (synonymous) terms from the literature in parentheses. Each nesting stage description includes reference to the predominant action patterns observed during the stage with the detailed action patterns following the stage in which we first recorded them. Videos of the nesting stages and the Transition Period are available as files in the online Supplemental Materials.

Subjects emerged from the water using a simultaneous quadrupedal crawl (SQC). The duration of ascent was dependent on abiotic factors such as beach width and tidal period, but varied little in the turtles we observed (Table 1). Latency periods occurred during ascent when the turtle paused for short periods of time. Latency periods included both HEDs and HLTs as well as GEX.

SQC.—The SQC is the primary flipper movement involved in ascent and descent and results in the forward movement of the turtle. The action pattern involves simultaneous retraction–abduction then protraction–adduction of all four flippers. The carpus or tarsus of each flipper has the most forceful contact with sand during the protraction–adduction stroke. The majority of the plastron remains in contact with the substrate. Protraction–adduction strokes result in forward movement of the turtle, and the turtle ceases forward movement during the retraction–abduction stroke.

HED.—The head raises, often corresponding with a GEX, and is then lowered.

HLT.—The head is laterally flexed, then returned to a medial position.

GEx.—At any of the above head positions, the throat expands and contracts rhythmically.

Of all observed nesting stages, body pitting was the second longest in duration (Table 1). In this stage, subjects used primarily paired front flipper sweeps (FFSW) and alternating rear flipper sweeps (RFSW) to clear away the top layer of soft, loose sand. Flipper movements caused slight forward progression as well as changes in the angle of the subject's body. Body pitting produced a mound of sand piled behind the turtle and a pit that accommodated the turtle, both resulting from sand displaced by flippers.

FFSw.—The FFSW involved either single or paired strokes and was observed in both the body pitting and camouflaging stages. The movement sprays sand rearward over a wide arc (∼120°). The FFSW begins as the front flipper moves through a cranial–caudal arc. Forward (cranial) movement is to an apex between 90° and 180° abduction, with rotation and pronation, so that the ventral flipper faces outward. Concurrent with forward flipper movement, the head and neck extend forward. Flexion and/or gravity lower the limb to the substrate, and the flipper immediately sweeps back. Concurrent with back-sweeping flipper movement, the neck retracts. This limb adduction is vigorous, such that the ventral limb commonly contacts the lateral carapace with a slapping sound.

RFSw.—The RFSW is seen in body pitting, covering, and camouflaging stages and was performed either singly or in alternating fashion. The rear flipper moves through a cranial–caudal arc of ∼150°. Forward (cranial) movement is to an apex where the distal flipper reaches the inframarginal region of the plastron. Immediately after reaching this point, the flipper rotates approximately 45° as it sweeps back. During body pitting and camouflaging, the movement sprays sand over a wide arc (approximately 90°) rearward. During covering, the turtle uses a more subdued version of the RFSW to move sand behind the turtle without causing the wide arcing spray.

The Transition Period occurred between body pitting and digging. Although the rear flipper flick sweep RFFSW was the predominant action pattern, we also recorded FFSWs and RFSWs (Table 2). HEDs and HLTs both occurred during the Transition Period.

RFFSw.—We observed RFFSW through analysis of the video-recorded footage, occurring during the final 1.9–5.7 min of the body pitting stage. The RFFSW begins as the rear flipper moves (extension, retraction–abduction) rapidly forward through a cranial–caudal arc of ∼90° to an apex located at the inframarginal region of the plastron (in the horizontal plane) and above the marginal scutes of the carapace (in the vertical plane). Immediately following this rapid forward flick, the flipper lowers and sweeps back (flexion, protraction–adduction), while contacting the substrate, to a point more medial than the start point. Subsequent movement is similar to a complete RFSW.

The digging stage resulted in excavation of an egg chamber by each subject, and was composed entirely of the Rear Flipper Flick Scoop (RFFSC; Table 2). The duration of each RFFSC increased during the excavation process as subjects needed to reach farther into the egg chamber to scoop out sand. The front flippers were not in motion during this period.

RFFSc.—The RFFSC is the dominant action pattern used during the digging stage and results in the excavation of the egg chamber. From a 45° medial angle, the rear flipper moves (extension, retraction–abduction) rapidly forward through a cranial–caudal arc of ∼90° to an apex located at the inframarginal region of the plastron (in the horizontal plane) and above the marginal scutes of the carapace (in the vertical plane). Immediately following this rapid forward flick, the flipper lowers as the digits flex (curl) and protracts and adducts below the horizontal plane of the plastron, below the tail, as the digits extend. Additional movements within this medial plane beneath the tail can be simple and brief (rapid flexion of digits and limb retraction) or complex and prolonged (circumduction simultaneous with pronation and supination, with hyper extension of digits). Following these flipper movements, the digits flex (curl) as the limb supinates and is raised above the horizontal plane of the plastron, then immediately pronates with digits extending as the limb lowers to the substrate, ventral surface down, abducting to a 45° medial angle (the starting limb position for this action pattern).

Oviposition began with a latency period. During oviposition, each subject positioned both rear flippers on either side of its tail, covering its egg chamber from view. While laying, the turtle's rear flippers showed subtle movement (retract, then extend less than ∼2 cm) during oviductal contractions. No front or rear flipper strokes occurred during this stage.

Using RFSWs, each subject filled the egg chamber using lateral-to-medial sand movement. No front flipper movement occurred during this stage. Left and right rear flippers were maneuvered independently of each other, often having two to three same-side flipper movements before opposite-side flipper movements. As sand filled the egg chamber, the subject would use rear flipper kneads (RFK) to compress the sand.

RFK.—The turtle uses RFK during the covering stage in conjunction with the RFSW. The movement appears to compact the sand that is displaced through the RFSW and results in the filling of the egg chamber. To begin, the extended rear flipper moves through a cranial–caudal arc of ∼90° to a lateral apex located ∼90° to the medial plane. This movement is singular and repeated through an arc of 45–90°. After 1–3 repetitions, the flipper adducts toward 0° (caudal-most) and performs repeated (2–7) rearward and downward pushing motions (full-limb flexion–extension) against the substrate.

Camouflaging was the longest stage with the highest number of active periods (Tables 1 and 3). Each subject began by using FFSWs, both singly and paired, to disperse sand over the covered egg chamber. As the stage progressed, RFSWs were incorporated. Front flipper strokes gradually moved the turtle forward, creating an elongated mound of sand.

The turtles employed an SQC to propel themselves forward toward the ocean. Latency periods during forward propulsion include both HEDs and HLTs, as well as GEX.

We calculated flipper stroke rates (periodicity) and head movement rates as action patterns per min for the eight video-recorded turtles. The flipper stroke rates for the body pitting, digging, covering, and camouflaging stages changed over the course of the nesting stage (Fig. 3). For the body pitting stage, front flipper stroke rates appeared to decrease from start to finish, whereas rear flipper stroke rates appeared to increase over the course of this behavior (Fig. 3A). As the camouflaging nesting stage progressed, the front flipper stroke rate tended to increase while rear flipper stroke rate tended to decrease (Fig. 3B). During the digging and covering stages, we observed only rear flipper movements, and stroke rate appeared to decrease over the duration of both stages (Fig. 4). Throughout each nesting stage, we observed an even ratio of right flipper (front and rear) movements to left flipper (front and rear) movements.

We calculated movement rates for both HLTs and HEDs, which were evenly periodic within each nesting stage. There were slightly more HEDs during earlier stages, however, and more HLTs during later stages (Z[17] = –0.577, P = 0.56).

We compared the nesting stage durations of our subjects with durations for Green Sea Turtles reported by other researchers (Hendrickson 1958; Bustard and Greenham 1969; Nishizawa et al. 2013; Table 4). Because ascent and descent durations are highly dependent on abiotic factors such as tidal period and beach width, we made comparisons only to active nesting stages at the nest site (body pitting through camouflaging). The total duration of the active nesting period was longest in the current study, with only the covering stage having a shorter duration than in the other studies. Based on our observed variation in nesting stage durations between individuals, a sample size greater than 33 would be required to detect duration differences of 50% or more between populations (power analysis for two-group independent sample t-test, α = 0.05, β = 0.20, effect = 0.5). We observed the greatest variation in nesting stage duration in camouflaging (range = 39.2–130.8 min). This observation is consistent with other studies that found camouflaging to have the greatest variation within their study populations (Hendrickson 1958; Bustard and Greenham 1969; Nishizawa et al. 2013). All of the aforementioned studies found that camouflaging had the longest duration of the nesting stages, however, with digging and body pitting being alternately second or third. Although our study found the mean duration of body pitting to be longer than that of digging (Table 4), the digging stage was longer in 62.5% of the observed turtles.

The seven distinct nesting stages we observed during our study corresponded to previously published descriptions of sea turtle nesting behaviors (Hendrickson 1958; Bustard and Greenham 1969; Wyneken 1997; Nishizawa et al. 2013). We identified six distinct flipper action patterns similar to those described by Hailman and Elowson (1992). Unique to our study was the RFFSW, an action pattern observed only during the Transition Period at the end of the body pitting stage, which was not recorded by either Hailman and Elowson (1992) or Nishizawa et al. (2013). We attribute the ability to distinguish this action pattern to details revealed by our reviewable, video-recording data collection method.

Our video-recording method provided an improved precision when recording time and occurrence of subtle behaviors during each nesting stage, the most notable of which is the description of a transition period between the body pitting and digging stages. Although flipper strokes at the end of a nesting stage can feature an action pattern common to the subsequent stage, these brief transitional periods most often involved a single hybrid flipper stroke. Our Transition Period consisted of a unique action pattern—RFFSW—that we recorded for all observed turtles. This Transition Period had not been described previously, although Carr and Ogren (1960: 21) did note a gradual change between body pitting and digging during which “the forefeet slowly decrease the pace of their thrashing, and the hind fins change over from a backward kick to a scooping push at the ground directly under the back of the shell.” Their description suggests a “scooping push,” which is different from the lateral sweeping motion with the hind flippers that we observed. We speculate that the function of the RFFSW is to clear away loose debris before the digging stage. This behavior might keep loose sand from entering the egg chamber as the turtle begins to dig.

Our ability to detect this stage, and associated action patterns, was a result of being able to review video footage of the nesting turtles at a slower speed, allowing the observation of small behavioral changes that might be difficult to observe in real time. Although video-recording and subsequent data coding are time intensive, the quality and quantity of data were higher than in traditional in-person observations. Historically, researchers have studied nesting behavior in marine turtles through visual observation alone (e.g., Hendrickson 1958; Bustard and Greenham 1969; Hailman and Elowson 1992; Mutalib et al. 2015). However, in-person data collection creates an inherently challenging environment in which to study complex and intricate behaviors. For example, visually focusing on all four flipper movements and head movements at the same time in low-light conditions might result in increased disturbance (Bustard and Greenham 1969; Hailman and Elowson 1992). Video-recording has been used to observe sea turtles' swimming behavior in captivity or the open ocean (e.g., Heithaus et al. 2002; Hays et al. 2004; Hochscheid et al. 2005; Reina et al. 2005), but we are not aware of any prior use of this technique for analyzing nesting behavior in this chelonian clade.

Although our seven nesting stages correspond to those described in other studies, we did not include the previously identified approach, wandering, and departure stages (cf. Hendrickson 1958; Bustard and Greenham 1969; Hailman and Elowson 1992; Witherington and Witherington 2015). Approach and departure stages have been defined for behaviors that involve swimming to and from the beach, respectively. Our observations did not extend to behaviors performed by the turtles in the water. Other studies have identified the wandering stage as a behavior taking place on the upper beach, after ascent but prior to oviposition (Hendrickson 1958; Fig. 2). We did not observe this behavior in any of our subjects. Wandering might be a means for sea turtles to judge the suitability of a site prior to oviposition. External stimuli such as sand density, light pollution, or obstacles might affect the performance of this behavioral stage. Wandering might vary with both population and beach conditions (Hendrickson 1958; Carr and Hirth 1962). For example, Green Sea Turtles nesting on dry sand beaches of Ascension Island make repeated attempts over multiple nights before laying eggs (Mortimer 1990). It is important to note that our results did not include wandering stages, which might cause variation in nesting durations seen between populations. Future assessments of nesting behaviors in sea turtles should attempt to determine if a lack of wandering represents a regional behavioral difference, or was caused by environmental factors such as beach characteristics.

Other researchers have posited that beach characteristics can cause variations in nesting behavior such as changes in nesting duration and/or rates of nest abandonment (Hendrickson 1958; Bustard and Greenham 1969; Mortimer 1990). The sand on our study beaches was medium- to coarse-grained (Finkl 2010), and we observed typical rainfall levels during the sampling period. We did not observe nest abandonment or difficulty in digging caused by sand characteristics. However, data collected during nesting surveys (under permit by the Florida Fish and Wildlife Conservation Commission [FWC]) from 2008–2017 indicate that a mean of 56.3% (n = 5484) of all Green Sea Turtle emergences within the Disney's Vero Beach Resort study region resulted in nest abandonment (personal observations). Weishampel et al. (2003) recorded a similar rate of nest abandonment at the Archie Carr National Wildlife Refuge.

Behavioral variations that we recorded within and between nesting stages might serve as indicators that denote temporal separation between stages that are behaviorally similar, but differ in susceptibility to disturbance. Two such stages are body pitting and camouflaging (Witherington and Witherington 2015). Each of these stages included RFSWs, and both single and paired FFSWs. Because of these similarities, distinguishing between nesting Green Sea Turtles that are body pitting and those that are camouflaging can be error prone. A potential consequence of this error could be that a turtle, thought to be camouflaging and minimally susceptible to disturbance, is approached (tagged, sampled) during its body pitting stage, when she is more likely to abandon her nesting attempt and return to the sea without laying eggs (Hendrickson 1958; Bustard and Greenham 1969; Nishizawa et al. 2013). The diagnostic behavioral features reported here can reduce this error: (1) During camouflaging, RFSWs are repeated as single, unilateral strokes, rarely alternating, whereas during body pitting, ∼25% of the RFSWs are alternating; and (2) the front flipper stroke rate during camouflaging is 70–85 strokes/min, whereas the rate for body pitting is 20–45 strokes/min. The stroke rate also has the potential to reveal how close in time a body pitting Green Sea Turtle is to the digging stage. At the beginning of body pitting, FFSWs are approximately four times more frequent than RFSWs; an inverse relationship tends to occur towards the end of body pitting (Fig. 3).

Night-vision video-recording of nesting sea turtles provides a reviewable, high-resolution methodology for behavioral analysis. Disturbance to the nesting behaviors of Green Sea Turtles was not apparent using our method. We propose our method as a technique to describe the action patterns that comprise the seven nesting stages accurately. By recording the behaviors, reviewing footage at a slower speed, and coding action patterns, we were able to identify a previously undescribed transition period for Green Sea Turtles. Use of this technique for other species of nesting sea turtles could reveal if other transitional nesting behaviors exist, and whether or not this behavior is conserved across similar species.

Using video-recorded data can further inform conservation managers tasked with measuring and responding to sea turtle nesting beach threats (e.g., physical barriers, human disturbance). Such threats to nesting sea turtles are likely to be underreported if the methodology for measuring behavioral patterns is unreliable. Our methods can facilitate the establishment of a baseline for nesting behavior against which any responses to anthropogenic disturbances can be compared. Having such a baseline available might also extend to an improved understanding of the environmental factors that influence sea turtle nesting and nest-site choice (Sutherland 1998; Witherington et al. 2011).

A specific use of the measures described here is to assess effects on sea turtles that are potentially subjected to interactions with humans involved in ecotourism programs. For example, operators within Florida's public turtle watch program (permitted by the FWC) are trained to lead participants to a nesting Loggerhead Sea Turtle and interpret her nesting behaviors as she lays eggs. Through effective interpretation and the chance to view a nesting sea turtle, this program benefits sea turtles by instilling conservation behaviors among its participants (Tisdell and Wilson 2005; Smith et al. 2019). Although conservation benefits presumably outweigh negative effects on an individual turtle, minimizing these effects should be an important goal. The ability to measure even minor disturbances to a nesting turtle chosen as a subject for a public turtle watch program could help project managers make programmatic changes to reduce the impacts of these disturbances. The North Atlantic Distinct Population Segment for Green Sea Turtles in the United States was recently downgraded from Endangered to Threatened (Fish and Wildlife Service and National Oceanic and Atmospheric Administration 2016), and the use of Green Sea Turtles as turtle watch (educational) subjects can now be considered by permitting agencies. Our results provide a means by which differences between nesting stages can be distinguished such that disturbances to nesting turtles are minimized. In turn, this will aid the evaluation of Green Sea Turtles as the subjects of turtle watch programs.

We thank the University of Florida, Archie Carr Center for Sea Turtle Research for equipment support, the University of Central Florida Marine Turtle Research Group for assistance in finding nesting turtles within their study area, and support from Disney's Animal, Science and Environment. We are grateful to J. Soltis for review of manuscript drafts. The Florida Fish and Wildlife Conservation Commission permitted this research under Marine Turtle Permit 071.

Supplemental material associated with this article can be found online. The following video recordings depict the nesting stages and the Transition Period.

Video S1.—The body pitting nesting stage with paired FFSWs and alternating RFSWs occurring simultaneously. https://doi.org/10.1655/Herpetologica-D-18-00015.S1

Video S2.—The RFFSW action pattern, where sand is flicked forward and swept to the side. This action pattern is predominantly seen during the body pitting to digging transition period. https://doi.org/10.1655/Herpetologica-D18-00015.S2

Video S3.—The RFFSC action pattern during the digging nesting stage. https://doi.org/10.1655/Herpetologica-D-1800015.S3

Video S4.—The RFK and RFSW behaviors that occur during the covering stage. https://doi.org/10.1655/Herpetologica-D-18-00015.S4

Video S5.—The camouflaging nesting stage includes FFSW action patterns, both single strokes and paired strokes, and RFSWs. https://doi.org/10.1655/Herpetologica-D-1800015.S5