Turtle patrollers find surprises in nests during inventories

BY ARLENE HALL, BGSTA SECRETARY

In last week’s article, we reviewed some of the data BGSTA turtle patrollers collect for FWC regarding nest inventory as well as some challenges we face while conducting inventories. This week, the focus is on data we collect involving the eggs and the hatchlings we may find in the nest. Such data includes the number of dead or live hatchlings found inside the nest, the number of empty (hatched) shells, the number of whole (unhatched) shells, and the number of “pipped” hatchlings (dead or alive) that only made it partway out of their shells by the time we found them at inventory.

The eggs of loggerhead and green sea turtles resemble ping pong balls in size and color, and they feel a bit rubbery when the female turtle deposits them in the nest. They are not hard shells like chicken eggs, but are tough enough to protect the hatchling embryo while it is incubating. A hatched egg may look torn up or may appear nearly intact but deflated, with a large opening from which the hatchling emerged. When first deposited in the nest, sea turtle eggs are white but often become discolored during the incubation period; this may be due to environmental factors such as the physical features of the nest (e.g., composition of the sand, temperature, water/tide inundation, bacteria and fungi), or internal factors such as embryonic infections, death and deterioration. Discoloration is likely caused by multiple factors and it doesn’t necessarily mean there was anything wrong with the eggs themselves. In fact, we find many discolored empty shells left behind by emerging hatchlings.

Finding a live hatchling during an inventory is always a special moment for both patrollers and observers alike. There is nothing to compare with watching an excited little hatchling as it enters the water and swims away. If you follow our Facebook page, it’s obvious by the number of times we post photos and videos of hatchlings that this is a highlight of our mornings. At times, we find live “pipped” hatchlings in the nest, still working their way out of the shell. These little ones are not yet ready for the water, so we hold them under specific, appropriate conditions until they are ready to be released. All work we perform is authorized and in accordance with FWC Marine Turtle Permit #25-123A.

Most inventories are relatively routine events, differing only in nest location and contents. But sometimes we encounter unusual things during an inventory, including some that are pretty rare, such as the following:

Leucistic Hatchlings

While most loggerhead sea turtle hatchlings are dark brown or reddish-brown in color, we have seen an exceptionally rare case of a white hatchling, known as a leucistic hatchling, on Gasparilla Island during the last couple of years. This happens when a genetic condition results in a significantly reduced amount of pigmentation, making the hatchling’s shell and skin appear white or very pale tan, while they retain the normal loggerhead eye color (brown). This is different than albinism, which is a complete loss of all pigment, resulting in pink eyes. While they still have the same instincts as other hatchlings, leucistic hatchlings do face more challenges than their normal counterparts. For example, they are more vulnerable to skin damage from the sun and to predators, since they lack the normal camouflage of normally colored hatchlings. In the 10 years (and countless inventories she has performed) since she has been on turtle patrol, FWC permit-holder Denise Juergens has only seen two leucistic hatchlings. 

Spacer Eggs

Just two weeks ago, I noticed two tiny egg-like objects amongst the normal sized eggs in a nest I was inventorying. They looked like mini turtle eggs, about one-third the size but the same color and with shells of the same material. However, they were most likely what are often called “spacer eggs,” non-viable or infertile eggs that do not contain a yolk and are not capable of hatching. Such spacer eggs are more commonly found in green or leatherback nests, but this was a loggerhead nest where the spacer eggs have been observed less frequently. There are several possible functions of these eggs, including predator decoy, helping to regulate moisture in the nest, creating some space to make it easier for hatchlings to emerge from the nest, or just being a byproduct of the egg-laying process (with no real function). Scientists are still investigating the exact function of these types of eggs. Denise estimates that we see these spacer eggs once every couple of years.

Polycephalic Hatchlings

A couple of years ago, I was inventorying a nest when just below the surface I found a deceased two-headed, or polycephalic, loggerhead hatchling. This is considered a rare birth defect in most animals but is more commonly observed in reptiles like turtles and snakes. Polycephaly may result from genetic or environmental factors, according to various studies. Most two-headed animals don’t survive for long, due to various physical and physiological challenges they face. I do know the hatchling I found had been alive for a little while at least, since it was out of its shell and had crawled within an inch or so of the surface, but it was deceased when I found it. Denise has only seen a two-headed hatchling twice in her 10 years of turtle patrol. Personally, it remains one of the most unique experiences I’ve had doing turtle patrol.

Nature never ceases to amaze!

Find out more: If you’d like to learn more about the BGSTA, including what we do and how you can support us, please visit our website at bocagrandeseaturtles.org