Behavior and diet composition of fiddler crabs in Guang-guang, Dahican, Mati City, Davao Oriental, Philippines

This paper aims to provide information about the behavior and diet composition of fiddler crabs. The large percentage of sediments present in the stomach of fiddler crabs proves that fiddler crabs play an important role in aerating the soil, which would help in the growth of mangrove and wetland plants. Observations were done in sandy, muddy, and coralline substrates for four months. Thirty fiddler crabs were collected for laboratory test of their diet composition. Sediments had the highest percentage in the stomach content of the fiddler crabs (60%), followed by chum (25%), and leaf particles (15%). The analysis of the fullness of their stomach showed that it was highly significant (df = 2, MS = 2.09, F = 34.34, p = 0.001). While the fiddler crabs ate all three colors of mangrove leaves, it preferred to forage on yellow leaves (n = 104) followed by the brown leaves (n = 78) and the green leaves (n = 77), proving that nutrient recycling occurs in the mangrove area. The existence of the fiddler crabs contributes to a more stable mangrove ecosystem. In addition, this study is the first assessment of fiddler crabs documented in Mindanao, Philippines. Results of the study can be used as a baseline for the protection of mangrove ecosystem species.