Loggerheads, greens, and a leatherback… Oh my!

May 31, 2024

By Dr. Jeffrey Schmid, Environmental Research Manager

The Conservancy’s 2024 sea turtle nest monitoring on Keewaydin Island started with an interesting twist. On April 23, the first crawl of the season was a non-nesting emergence, or false crawl, where the turtle made her way up the beach but encountered stumps and snags that caused her to turn back to the Gulf. The track had some interesting features indicating this was not the typical loggerhead turtle commonly encountered on the island.

First, the pattern of the flipper indentations in the sand indicated the female turtle used both front flippers simultaneously, which is typical of green sea turtles, rather than the alternating flipper movements of loggerheads. Secondly, there was a noticeable tail drag down the center of the track characteristic of the relatively larger tails of green turtles. Although green turtles nest infrequently on Keewaydin, their numbers have been increasing over the past decade as has been the case for the much larger nesting aggregation on the east coast of Florida.

However, the sheer size of the turtle track left on Keewaydin suggested that this was not a green turtle but that of the leviathan of sea turtles, the leatherback. Both species share the same track characteristics but the much larger size of the leatherback sets them apart from the green turtles. The deep flipper depressions the turtle left as she hauled out of the water measured at least four feet across but the outer flipper drags in the sand added at least another foot to each side, giving a total width of over six feet. The following day, the Sanibel-Captiva Conservation Foundation recorded their first nest of the season on April 24 and, coincidentally enough, it was from a leatherback. The last time a leatherback nested on Sanibel was four years earlier.

The first leatherback nest recorded in Collier County was on Keewaydin in 2015 and the most recent nesting on Collier beaches was in 2022, just north of Doctor’s Pass. Given leatherbacks are such infrequent nesters, the false crawl on Keewaydin and the subsequent nest of Sanibel probably were the same female turtle looking to deposit her eggs on a favorable stretch of beach. Moreover, leatherbacks return to nest every 2-3 years so the recent 2-year interval of nests on southwest Florida beaches (2020, 2022, and 2024) may very well be the same female turtle. These collective observations demonstrate the interconnectivity of the various beaches along our coast.

As for the 2024 nesting season on Keewaydin thus far, loggerhead emergences started slow but have picked up steam in the past week. Conservancy interns are busy monitoring southern portions of the island during the night, braving relentless mosquitos and sand gnats, while the northern portion is patrolled during the oppressive heat of the day. Upwards to 10 nests are being recorded each day as we head into the peak of nesting season and this could very well be another record year for loggerhead nests, as have the last 2 seasons. In collaboration with Rookery Bay National Estuarine Research Reserve, a dashboard has been created that allows a viewer to monitor nesting data on Keewaydin as it is being entered in the field.