COSM

Nest Validation

Nest Validation

 St. Catherines’ beaches are patrolled daily as soon after sunrise as is possible. Faculty and/or interns drive along each beach in ATVs looking for crawlways and/or beached (stranded) sea turtles or whales. Because beaches can only be traversed when the tide is out or partly out, it is necessary to time monitoring activities with tidal cycles, which vary from day to day. If travel by ATV is not possible, we may use bicycles or walk.

When a crawlway is found, its probability of being a nest is assessed by looking for a covering pit, thrown sand, or by observing significantly different lengths of entrance and exit crawlways indicating significant time was spent on the beach by the turtle. Initial assessment is finished while keeping off the crawlways, nest, and surrounding area in order to preserve maximum data.

Nonnesting Crawl 9067

Non-nesting crawlway on middle part of South Beach; no indications of nesting! … a simple loop.

nest_unob-94-038

Simple, unobstructed, backbeach nest [94-038] has elliptical disturbed area (covering pit) and thrown sand! … a Loggerhead nest.

If the presence of a nest is indicated, we measure and photograph the crawlway and the covering pit, sketch the arrangement of the nest components in our notebook, and write a description of the sequences in the nesting turtle’s behavior to determine the sequence of events, directions of entrance and egress from the nest, and any unusual events during nesting. This process allows us to predict the position of the body pit and the position of the egg chamber within the covering pit. Once all data are taken and recorded, the nest is excavated.

Photographic documentation of obstructed, complex backbeach nest [00-091] deposited against scarped dune face behind )and through?) Spartina wrack mat mid-position on South Beach (7/21/00). Bucket over egg chamber.

Notebook sketch of nest to left [00-091] documents an abstraction of the nest morphology.

Validation of sea turtle nests on St. Catherines Island proceeds by digging through the overlying sand of the body pit and covering pit until laminated sands of the backbeach are encountered. The excavation is then dug laterally until the disturbed sand filling the egg chamber neck is encountered. It can be recognized by its brecciated or marbled appearance, its circular pattern of sand surrounded by the contour-like (ribbon-like) pattern of the undisturbed backbeach sediments lying just below the body pit, and its softness, the consistency of soft butter.

nest_form_2007

A sea turtle nest form can be generated on the computer and printed either as a model template or as loose leaf sheets for documentation of each nest.

Digging is accomplished using straight edged shovels, trowels, or fronds of the cabbage palm. The stirred-up sand of the covering pit is easily moved outside of the nest area until the undisturbed, laminated backbeach sand of the body and covering pit floor are encountered yielding a contour-like pattern due to the laminations of heavy minerals and quartz sand. This surface, also affording a textural contrast between soft sand above and firm sand below, is followed into the body pit towards its deepest part until the bulls-eye of the egg chamber neck, the egg chamber discontinuity, is discovered.

The loose sand of the covering pit is easily removed using a trowel, a straight-edged sand shovel, or a stiff Palm frond scraper.

Discontinuity 8895_measuring

The egg chamber neck shows up as a bulls-eye discontinuity where the neck cuts through the sand of the backbeach beneath the covering pit.

Once the egg chamber neck is located, a small hand-sized tunnel is dug vertically to confirm the presence of eggs in the egg chamber. Once eggs are seen or felt, depth from the beach surface to the top egg is measured and the tunnel is rapidly backfilled and tamped to its original consistency. The egg chamber is marked on the nest sketch, and its cross section is measured and its center is marked with a piece of beach wrack so its exact position will remain visible as the excavation is backfilled with sand taken from it during excavation.

Discontinuity 94-091 86812

Egg chamber discontinuity of loggerhead sea turtle nest [94-091] indicated by textural change in interlaminated backbeach sands (banded) and bioturbated backfilling of egg chamber neck (marbled circular area). Scale with centimeters oriented toward the sea (bottom). South Beach at 4.893 km.

The placement of the nest relative to the beach is assessed and a decision to leave the nest in place or to move it is made. If let in place, the nest is conserved by a process mandated by Georgia DNR and modified to our standards to control predators and the nest will be monitored on a daily basis.

Last updated: 7/27/2016

Sea Turtle Program at St. Catherines Island • (912) 478-1744 • jgaskin@georgiasouthern.edu