Every year Philippine crocodiles mate in January or February. They start making nests usually in April, May or June, depending on weather conditions. There are two types of nest; a hole nest which is a hole of around 50 cm. deep, covered with some vegetation, and a mound nest, which is a shallow depression in the ground with a big mound of vegetation on it. A mound nest can be up to 50 cm. high and more than 150 cm in diameter.
Because we want to find out more about the nesting behavior of Philippine crocodiles, and the reasons why they sometimes make a hole nest and at other times a mound, we do research.
We always measure the nest and after hatching we count the number of eggs; we place data-loggers in the nest and outside it to record temperature, light intensity and humidity in an near the nest; we place camera traps near the nest to see if the mother comes back to the nest to guard it against predators and perhaps to assist the hatchlings come out of the eggs. Often we have students from the Philippines or from other countries (usually the Netherlands) to help with the research.
Since the start of the head-start program and nest protection, nesting success has significantly increased. In 2008 and in 2010, 6 nests were recorded. In both years 5 of those nests were successful