Effectiveness of Concealed Nest Protection Screens Against Domestic Predators for Green (Chelonia mydas) and Hawksbill (Eretmochelys imbricata) Sea Turtles

Mammalian depredation of nests has been listed amongst the most significant threats to hatchling success in sea turtles. In 2013, at least 13% of green turtle (Chelonia mydas) and 25% of hawksbill turtle (Eretmochelys imbricata) nests were lost to domestic dog predation on Playa Norte, Costa Rica. In 2014 and 2015, plastic and bamboo protective screens were deployed to protect nests. Screens were deployed at different stages of the incubation period and the success of the nests analyzed. Predation rates increased as the seasons progressed with October and November being the peak depredation months, as well as the peak for hatchling emergences. Eggs remaining in nests that had been partially depredated had a significantly lower percentage of hatching success than eggs in undisturbed nests. There was no significant difference between timing of deployment and likelihood of a screen being breached. The likelihood of a screen being breached was highly dependent on the type of material used; bamboo screens were ca. 153% more effective than plastic and successfully prevented the complete predation of ca. 48% of nests. Bamboo screening is an inexpensive, environmentally inert, yet labor-intensive method for reducing nest depredation by domestic dogs. This screening method does not impact the hatching or emerging success of the nest.