Each year, we observe more and more sea turtles that don't leave Kefalonia after the end of summer, but instead prefer to spend the winter here.
Sea turtles swimming along the harbour of Argostoli are a fairly common sight during the summer months. Some of these turtles visit the area to lay their nests on the sandy beaches of Kefalonia. In winter, they migrate away to warmer waters in the bay of Gabes or the north Adriatic, where they will find food to recover from the exhausting process of reproduction and replenish their fat reserves. They will come back to their nesting habitat in two to four years, though male turtles return more often.
More than a decade ago, Michael White observed (page 116) that there were no turtles in the bay of Argostoli during the winter months. He recorded a period of five months during which turtles were not seen in the bay. In the last four years, though, we regularly observe a small number of turtles residing in the bay. They prefer to swim near the surface and forage on sunny days, when the surface waters warm up.
Two important questions arise from these observations:
- Is this caused by warmer waters or because the turtles can find more food in the bay?
- Is this change in their behaviour an adaptation for survival or an ecological trap?
These questions require long-term data collection and analysis, and are important for our understanding of how humans affect this migratory animal's ecology, and what are the consequences for its survival.