Barb examines eggs in the lab incubators.
Photo courtesy of Earthwatch Institute
Finding Out If the Eggs Are Fertile
by Barbara Bell, expedition team member

Hi, I'm Barb. I'm a graduate student and a member of the expedition team. I have always liked reptiles and dinosaurs. Scientists believe that leatherbacks are a lot like dinosaurs, so it is especially exciting to work with them! The turtles are HUGE! It is really incredible to watch them crawl out on the beach and think about what it would have been like 10,000 years ago to see them doing exactly the same thing now. It's like being in a time machine.

When I am not out looking for turtles at night, I am inside in our field lab examining eggs in the incubators. Incubators are boxes that allow me to control the temperature and amount of moisture that the eggs are exposed to. I have been trying to find out why the number of hatchlings born at Playa Grande has been much lower in recent years than in the past. One reason may be that females are laying eggs that are not fertile.

My job here is to discover how many of the eggs from the female leatherbacks' nests are fertile. My study focuses on 30 female turtles. I take ten eggs from each of their nests and put them in incubators filled with sand from the nesting beach. The rest of the eggs in the nests go into the outdoor hatchery.

Each day I examine the eggs in the incubators. Leatherback eggs are a pale grayish-white color when they are laid. An egg that has a living, growing embryo inside will develop an opaque white patch on the top of the eggshell within ten days after it's laid. This happens when the embryo has made its way to the eggshell and has begun to attach to the shell. If an egg does not develop a white spot after 15 days, I open it up and examine the insides to see if I can find out if there was ever an embryo inside.

I expect the first eggs will hatch early this month. We will release the hatchlings on the beach near the place where they were laid. This may help them remember the beach where they were born so that they come back when they grow up.

After all the eggs hatch — both the eggs from the incubators and the ones in the hatchery — I will be able to determine how many eggs from the nests of the 30 females were fertile.