Collecting data

Seeing flatbacks nesting again has been awe inspiring. We are in a unique situation where we get to see a lot of turtles nest during the day. No other species of sea turtle nests consistently in daylight hours. It is possible that we have seen more daylight nesting by sea turtles than anyone. It is a great opportunity to be able to observe their nesting behaviours. On an afternoon high tide turtles will, all of a sudden, appear offshore swimming parallel to the beach and lifting their heads as they search for a nesting spot on the beach. Almost simultaneously turtles will then start emerging from the surf and make their way up the beach. Some get to the edge of the tide line and change their minds and turn, then head back out through the waves. In some parts of the island the dunes are quite high and many turtles go to a lot of effort to get over them – just dragging their 200lb weight up the beach is hard enough, let alone trying to get up a steep dune! But they are very determined to ensure that their eggs are not laid in a position where they will get inundated by the tide. Once they find an area they excavate a huge ‘body pit’ with their front flippers, then they start digging an egg chamber with their back flippers, delicately flicking away sand in a coordinated manner. Once dug they will start laying about 50 to 60 eggs, before covering them and patting them with their hind flippers and then ‘filling’ with their front flippers. It is the stage after laying when we collect data when they are still in an almost hypnotic state – we measure and then tag them with small, numbered titanium tags. We record nest location, nesting success and other data. The tags are important as we can identify individual turtles – we can see when they have nested in previous seasons and the time between migration, and in a couple of weeks we will start seeing tagged turtles again which will provide us with inter-season renesting intervals. Some tags will even tell us where they migrate, which can be thousands of kilometres away.