Application of Aerial Photographs and Coastal Field Data to Understand Sea Turtle Landing and Spawning Behavior at Kili-Kili Beach, Indonesia

We investigated sea turtle landing and spawning behavior along 1.4 km of Kili-Kili Beach in East Java, Indonesia, by combining aerial photographs and field survey data. In the study, we surveyed marks of sea turtles landing and spawning on the beach and utilized aerial photographs, beach profile survey records, grain size measurements of the beach material, and tide records to understand the behavior of the turtles. Firstly, aerial photographs are processed into ortho-mosaics, and beach surfaces are classified into land cover categories. Then, we calculate the number of spawning and non-spawning instances for each category, visualizing landing positions to identify local concentrations. Spawning distances from the waterline are estimated, and beach stability is evaluated by analyzing the temporal elevation change through standard deviation. Our findings reveal preferred spawning locations on bare sand surfaces, around 8 to 45 m from the waterline, with beach elevations ranging from 1 to 5 m. The standard deviations of beach elevation were between 0.0 and 0.7 m, with a mean slope of 0.07. This information is important for effectively conserving sandy beaches that serve as spawning sites for sea turtles.