Neglecting low season nest protection exacerbates female biased sea turtle hatchling production through the loss of male producing nests.

In the eastern Pacific, peak olive ridley sea turtle (Lepidochelys olivacea) nesting occurs during the warmest months which coincide with the rainy season, yet as nesting takes place year-round, the small proportion of the nests laid during dry-low season are exposed to contrasting environmental conditions. Most of the studies on Pacific coast sea turtles have estimated sex ratios produced during the rainy-high season when the majority of conservation activities take place. Thus, dry-low season nests have on the whole been overlooked. Here we compared sex ratios and hatchling fitness for offspring produced during the dry and rainy seasons during 2015. We found that protected olive ridley clutches incubated during the dry-low season were exposed to lower temperatures, yielded higher hatchling success, produced 100% male offspring and larger, heavier hatchlings with better locomotor abilities. Our results highlight the critical value of monitoring and protecting sea turtle nests beyond the peak season (when nests can be protected more efficiently) to include low season nests, albeit at much lower densities, but which by yielding higher proportions of males and with greater locomotor capacities may be the key to population viability and adaptation to anthropogenic climate change.