All sea turtles share a similar behavior pattern when nesting. Most turtles found nesting on the east coast of the United States have distinct "trademarks" or characteristics which can be used to identify what species of turtle nested. Typically this can be accomplished through the examination of the tracks or the nest site. Becoming familiar with the nesting process and the "trademarks" of each turtle enables beach monitors to more accurately identify what species of turtle was present, and whether the turtle laid eggs or not. The following is a step by step behavioral process that nesting sea turtles typically follow.

THE CRAWL:
Generally, female sea turtles will swim in towards shore during the late afternoon or early evening just prior to sunset. At some point after nightfall, the nesting turtles will emerge from the ocean and crawl up the beach to find a suitable nesting site. It is possible to identify the species of the turtle that emerged by the tracks left in the sand. Key crawl characteristics include:

• Alternating or Simultaneous right and left flipper marks
• Presence or Absence of tail marks down the center of the tracks
• Relative Width of tracks indicating the size of the turtle

Loggerhead sea turtle tracks are smaller on average than green and leatherback turtle tracks. They exhibit alternating right and left flipper tracks and no tail marks. Both green turtles and leatherbacks exhibit simultaneous right and left flipper marks and the presence of tail marks down the center of the tracks (LeBuff, 1990). Leatherback tracks are the widest of all species' tracks.

Tracks will also indicate the direction in which the turtle was traveling. Examining where the turtle pushed the sand back in an effort to move herself forward will aid in determining the direction that the turtle was traveling in. Determining the direction that the turtle was moving helps identify where she may have nested. With old tracks, direction may be difficult to determine.

THE BODY PIT:
Once a nesting site has been chosen, the female will prepare the area by clearing the sand and brush away with all four flippers. In some cases, a large pit is excavated with the turtles' flippers. Loggerhead turtles make relatively shallow body pits, commonly in the form of two long, narrow hills of sand on either side of the turtle's tracks moving towards her nest site. Green turtles, however, have a characteristically large and deep body pit. Greens may leave a body pit that is one to two meters in diameter and up to .5 to 1.0 meters deep. Hawksbill sea turtles create little to no body pit and usually nest in the brush landward of the open beach. Both loggerhead and green turtles tend to nest on the open beach.

THE EGG CHAMBER:
Upon completing the body pit, turtles will begin to excavate an egg cavity with their rear flippers. Using these flippers as shovels, the turtles will scoop out sand from the egg chamber, alternating their flippers as they dig. Sand that is scooped out of the cavity is spread to the side of the hole. The depth of the egg chamber is determined by the length of the rear flippers (van Meter 1983). If a turtle is missing a large portion of one or both of her rear flippers, her egg chamber may be relatively shallow. The shape of most egg chambers beneath the sand resembles an inverted light bulb.

LAYING THE EGGS:
When the egg chamber has been completed, the turtle will start depositing her eggs. Once a turtle has begun to lay her eggs, she becomes almost oblivious to any disturbance around her. Most loggerhead turtles spread their rear flippers beside their nest during deposition. The turtles will position their cloaca over the hole and begin dropping eggs, two and three at a time, into the chamber. Once egg laying has commenced, the turtle will often slightly curl their rear flippers as eggs are deposited. This action is an indicator that the turtle has begun to lay her eggs and can be approached by researchers without disturbing her. Unlike the loggerhead, leatherbacks and green turtles generally extend their rear flippers directly behind them during egg deposition (Ibid.). Some green turtles have also been observed to cover the exposed egg chamber with one of their rear flippers. With shallow egg chambers, some eggs may spill out on either side of the chamber. These eggs may be crushed by the turtle as she begins to fill in her egg chamber after she has deposited the clutch.

COVERING THE EGGS:
Once the turtle has deposited all of her eggs, she will cover the egg-filled chamber with sand, shoveling it in and packing it down with her rear flippers. Some species slap down or knead the sand, using the weight of their bodies to pack down the area.

NEST OBLITERATION:
When the turtle has finished covering and packing the sand down on top of her eggs, she will then begin to swipe sand with her front flippers, flinging it back over the nest site. A turtle will ONLY do this if she has laid her eggs (Florida Department of Natural Protection, 1994). The resulting nest site will have a characteristic mound of sand over part of the turtle's tracks and nest site, as well as a small escarpment made from where the turtle used her front flippers to scrape away at the sand, flinging it back over her nest. Leatherback and green turtles both leave characteristically large and widely flung mounds of sand. When covering is complete, the turtle will crawl back to the ocean, leaving tracks as she exits the beach.

FALSE CRAWLS VS. NESTS:
Occasionally, a nesting turtle may emerge from the ocean but not lay eggs on the beach. This event, characterized by an abandoned nesting attempt or simply a U-shaped crawl from the ocean up the beach, then back to the water, is called a False Crawl, Emerge No Lay, or Abandoned Nesting Attempt. A turtle may false crawl for a number of reasons, some of which include:

• She is disturbed by lights, noise or other unusual activities
• She encounters and obstacle while crawling up the beach
• She encounters roots, debris or rocks while digging her egg chamber
• The sand does not have the right consistency or moisture
• Her egg chamber collapses
• Other reasons not known

A turtle may false crawl at any point in her nesting sequence up to the point where her eggs are laid. A turtle may even complete her egg chamber and for some reason not deposit her eggs. The key factor that indicates whether a turtle has laid her eggs or not is the presence or absence of a mound of sand and the escarpment created when the turtle flung the sand back over her nest site. A turtle will not obliterate her nest site if she has not deposited eggs.

Depending upon the species and the temperature of incubation, the time between egg deposition and hatchling emergence will range anywhere from 45 to 75 days (LeBuff, 1990). Within the first 12 hours after deposition, the vitelline membrane (the cell wall of the egg that plays an important role in gas exchange through the egg wall) attaches to the interior of the egg shell (Ibid.). If the egg's orientation changes after the attachment forms, the membrane will detach from the egg wall and development will cease (Ibid.). Great care is usually taken by researchers if eggs must be moved for any reason more than six to twelve hours after a turtle has nested.

NEST EMERGENCE:
After incubating beneath the surface of the sand for approximately two months, the young turtles will begin to hatch out of their shells. Hatchlings may remain within the egg chamber several days after hatching. Hatchlings found in the process of crawling out of their shell are called pipped. The movement of fully hatched and pipping turtles while in the egg chamber serves to loosen the sand, allowing it to trickle down to the bottom of the nest. This process acts as a sort of elevator: the greater the movement caused by hatchlings, the greater the amount of sand filtering down to the bottom of the nest, there by elevating the turtles closer to the surface.

Emergence occurs primarily at night. The temperature of the surface sand and sun/ambient temperature during incubation are key factors that determine when hatchlings will emerge from their nest. Once the surface layers of the beach cool after sunset or after a rain storm, the turtles will 'erupt' en mass and proceed to crawl down the beach to the water (Ibid.). Hatchlings orient themselves to light reflected off the water and beach, away from the darker vegetated areas typically found landward along the beach (Ehrenfield, 1968). Over a hundred hatchlings may emerge from a nest at one time.

FRENZY:
From the time of nest emergence up to 24 to 72 hours after entering the ocean, hatchlings remain in a state often referred to as a "frenzy". During this period, hatchlings remain in a swimming state. It has been suggested that this may serve to get the hatchlings away from shore and coastal predators, out to deeper waters (van Meter 1993). Very little is known about sea turtles from the point that hatchlings enter the ocean until at least 20 years later when the females become sexually mature and come ashore again to nest. This lack of information makes sea turtle management and conservation difficult.

Ehrenfield, D. W. 1968. The role of vision in the sea-finding orientation of the green turtle (Chelonia mydas) 2. Orientation range and spectral sensitivity. Animal Behavior 16:281-287.

Florida Department of natural Protection 1994. Nesting Beach Monitoring Techniques. TOPIC: Crawl Identification. Monitoring protocol literature from FL DEP. Tequesta, FL.

Lebuff, C. R. 1990. The Loggerhead Sea Turtle in the Eastern Gulf of Mexico. Caretta Research Inc., Sanibel, FL. Pp 185, 190.

van Meter, V. B. 1983. Florida's Sea Turtles. Florida Power and Light Company. Miami, FL. P 25