Clutch of 121 leatherback eggs at the bottom of a nest cavity
Photo courtesy of Earthwatch Institute
A Leatherback Nest
by Dr. Richard Reina, scientist

The dry season and summer are finally here! The turtle numbers are picking up, although there are still not as many nesting females as last year.

A few nights ago ten turtles came ashore to nest. On another night there were 11 turtles — all between 11:30 pm and 2:30 am. The good news is many of these turtles are "newcomers" this season. That means that they are likely to return to nest several more times between now and March. Last year the average number of clutches was about seven per turtle.

How do we know if turtles are newcomers? If they have no PIT (Passive Integrated Responder) tags it means that it is the first time that they have come here. Other turtles have tags from previous years, which means that they are returning for at least a second season. We give the new turtles PIT tags by injecting a tiny electronic chip in their right and left shoulder muscles.

On the night that there were 11 turtles, we relocated all the nests to our beach hatchery. The last very high tide for the season is in a few days — around the time of the full moon. After that we will not have to move so many nests. It takes a long time to dig 11 nests! The turtle gracefully manages, with her back flippers, to dig a nest 30 inches deep in about 20 minutes. It takes us about 30 minutes to do the same.

Digging a nest is not as easy as it might seem. It helps to have long arms. First, you make a hole about ten inches wide and then dig straight down about 2.5 feet. If the sand is too dry the walls will cave in. At the bottom, you dig a cavity about 14–20 inches wide. This is where the eggs go.

The yolked (fertile) eggs are about 2.5 inches wide. We wear gloves and carefully place them at the very bottom of the cavity. The yolkless (infertile) eggs are smaller and vary in size. They are placed on top of the other eggs. All of the eggs are soft to the touch and are not breakable like bird eggs. The nest is then filled in with sand and gently packed down. Some scientists think that the yolkless eggs provide space for the hatchlings to dig their way through the sand up to the surface.

So far this season, about 120 turtles have nested, and about 85 nests have been relocated. That means a total of about 5,000 eggs. In about two weeks - around December 12 — the first clutch of eggs, laid in mid October, are due to hatch. Stay tuned for updates from Jen and Dave.