The sea turtle nesting season for 2015 is well underway in Kefalonia and across the Mediterranean sea. Sea turtles emerge on the sandy beaches of the island and crawl towards the back of the beach. There, they dig a vase-shaped eggchamber with their back flippers and lay an average of 90 eggs, which they then carefully cover and camouflage to protect them from overheating and from predators.
Every morning, volunteers at our sea turtle conservation project walk along the nesting beaches to identify, record, and protect sea turtle nests that were laid during the previous night. They locate the eggs to ensure the visual confirmation of the exact nest location and to assess whether they need to move them to a safer location. They then fence off a small area above the nest and place a sign to notify visitors.
We are sometimes asked why we mark the nest locations instead of leaving them hidden in the sand, as they would naturally be. This is a reasonable question that is often backed by a fear that people with malicious intentions could easily find and damage the nests. But whether sea turtle nests should be marked or not is not merely a matter of fear, opinion, or preference; it is a carefully considered decision based on published scientific literature and the analysis of data collected here in Kefalonia.
The risk of accidental damage is greater than the risk of vandalism
Ever since we started protecting sea turtle nests in Kefalonia, less than two percent (<2%) of nests have been vandalized by humans. In most cases, only the marking tape or sign were removed. One egg from one nest is known to have been damaged. This results in a 0.7% risk of damage to a nest and a 0.008% risk of damage per egg.
In contrast to this, many of the nesting beaches are heavily used for tourism; most of the beach is walked over by visitors and driven over with ATVs or tractors. The risk of damage from the above, as well as from tourists laying their towels, placing their umbrellas, or digging over unmarked nests is far greater in Kefalonia than the probability of intentional damage to a marked nest. Most people will respect a sea turtle nest and its markings out of respect and love for sea turtles, but damage to a nest or removal of its protection is also illegal and punishable by law.
Even after a nest has been damaged, a marked nests has much better chances of successful incubation than an unmarked nest. On the nest mentioned above, in which an egg was damaged, our volunteers knew the nest was damaged, removed the broken egg, cleared any liquids to prevent the development of bacteria, and re-covered the eggs with moist sand to keep them from overheating and to prevent predators from reaching it. Because the nest was marked, our volunteers knew it was damaged and were able to restore it. If the nest was unmarked, none of the eggs would have incubated and no hatchlings would have emerged.
Assessment of inundation
Kefalonia is known for the rough weather affecting its shores. Many of the nesting beaches continue changing in both length and width even through the nesting season. Nests that are laid too close to the sea are relocated further back into safety from the waves, but due to the dynamic nature of Kefalonia's beaches, nests that were initially at a safe distance from the sea are often also affected when the loss of sand and the rising seas coincide. Marking all nest locations allows our teams to quickly assess each nest's condition after a storm and to relocate those that are inundated back to safety.
3. Ability to manage hatching
When a nest completes its incubation, many emerging hatchlings would never make it to the sea because of the high levels of light pollution affecting Kefalonia's nesting beaches. After a nest has been protected from accidental damage, light pollution is the greatest risk factor for emerging hatchlings. Nests can be shaded so that distant lights are not seen by the hatchligns as they emerge. Where lights are closer and brighter, the nest must be monitored throughout the night and any emerging hatchligns must be moved to a darker part of the beach, where they will be able to crawl to the sea. These two widely used rescue methods can only be used when the exact location of the nest has been marked.
4. Public awareness of sea turtle nests
It's hard to promote awareness about the presence of sea turtle nests on a beach when the public cannot see them. This is not to say that the nests should be put on show, but when the nests must be marked for the previous reasons, they also serve to instill in locals' and visitors' conscience that these ancient mariners continue to visit Kefalonia's to deposit their offspring on the same beaches we use for recreation; and a reminder that these nests must be protected if sea turtles are to survive.
For these reasons, all science-based conservation organizations that protect sea turtle nests in Greece mark nest locations where possible to protect them from damage.